diff --git a/Documentation/admin-guide/cgroup-v1/memory.rst b/Documentation/admin-guide/cgroup-v1/memory.rst
index faac50149a222..2cc502a75ef64 100644
--- a/Documentation/admin-guide/cgroup-v1/memory.rst
+++ b/Documentation/admin-guide/cgroup-v1/memory.rst
@@ -64,6 +64,7 @@ Brief summary of control files.
 				     threads
  cgroup.procs			     show list of processes
  cgroup.event_control		     an interface for event_fd()
+				     This knob is not available on CONFIG_PREEMPT_RT systems.
  memory.usage_in_bytes		     show current usage for memory
 				     (See 5.5 for details)
  memory.memsw.usage_in_bytes	     show current usage for memory+Swap
@@ -75,6 +76,7 @@ Brief summary of control files.
  memory.max_usage_in_bytes	     show max memory usage recorded
  memory.memsw.max_usage_in_bytes     show max memory+Swap usage recorded
  memory.soft_limit_in_bytes	     set/show soft limit of memory usage
+				     This knob is not available on CONFIG_PREEMPT_RT systems.
  memory.stat			     show various statistics
  memory.use_hierarchy		     set/show hierarchical account enabled
                                      This knob is deprecated and shouldn't be
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 4c97cb40eebb6..b5223adf2512c 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -33,6 +33,7 @@ config ARM
 	select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT if CPU_V7
 	select ARCH_SUPPORTS_ATOMIC_RMW
 	select ARCH_SUPPORTS_HUGETLBFS if ARM_LPAE
+	select ARCH_SUPPORTS_RT if HAVE_POSIX_CPU_TIMERS_TASK_WORK
 	select ARCH_USE_BUILTIN_BSWAP
 	select ARCH_USE_CMPXCHG_LOCKREF
 	select ARCH_USE_MEMTEST
@@ -68,7 +69,7 @@ config ARM
 	select HARDIRQS_SW_RESEND
 	select HAVE_ARCH_AUDITSYSCALL if AEABI && !OABI_COMPAT
 	select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7) && !CPU_32v6
-	select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU
+	select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU && !PREEMPT_RT
 	select HAVE_ARCH_KFENCE if MMU && !XIP_KERNEL
 	select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32 && MMU
 	select HAVE_ARCH_KASAN if MMU && !XIP_KERNEL
@@ -110,6 +111,7 @@ config ARM
 	select HAVE_PERF_EVENTS
 	select HAVE_PERF_REGS
 	select HAVE_PERF_USER_STACK_DUMP
+	select HAVE_PREEMPT_LAZY
 	select MMU_GATHER_RCU_TABLE_FREE if SMP && ARM_LPAE
 	select HAVE_REGS_AND_STACK_ACCESS_API
 	select HAVE_RSEQ
@@ -125,6 +127,7 @@ config ARM
 	select OLD_SIGSUSPEND3
 	select PCI_SYSCALL if PCI
 	select PERF_USE_VMALLOC
+	select HAVE_POSIX_CPU_TIMERS_TASK_WORK if !KVM
 	select RTC_LIB
 	select SYS_SUPPORTS_APM_EMULATION
 	select THREAD_INFO_IN_TASK if CURRENT_POINTER_IN_TPIDRURO
diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
index 164e15f26485d..666da94ed9b77 100644
--- a/arch/arm/include/asm/thread_info.h
+++ b/arch/arm/include/asm/thread_info.h
@@ -54,6 +54,7 @@ struct cpu_context_save {
 struct thread_info {
 	unsigned long		flags;		/* low level flags */
 	int			preempt_count;	/* 0 => preemptable, <0 => bug */
+	int			preempt_lazy_count; /* 0 => preemptable, <0 => bug */
 #ifndef CONFIG_THREAD_INFO_IN_TASK
 	struct task_struct	*task;		/* main task structure */
 #endif
@@ -152,6 +153,7 @@ extern int vfp_restore_user_hwstate(struct user_vfp *,
 #define TIF_SYSCALL_TRACEPOINT	6	/* syscall tracepoint instrumentation */
 #define TIF_SECCOMP		7	/* seccomp syscall filtering active */
 #define TIF_NOTIFY_SIGNAL	8	/* signal notifications exist */
+#define TIF_NEED_RESCHED_LAZY	9
 
 #define TIF_USING_IWMMXT	17
 #define TIF_MEMDIE		18	/* is terminating due to OOM killer */
@@ -166,6 +168,7 @@ extern int vfp_restore_user_hwstate(struct user_vfp *,
 #define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)
 #define _TIF_SECCOMP		(1 << TIF_SECCOMP)
 #define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
+#define _TIF_NEED_RESCHED_LAZY	(1 << TIF_NEED_RESCHED_LAZY)
 #define _TIF_USING_IWMMXT	(1 << TIF_USING_IWMMXT)
 
 /* Checks for any syscall work in entry-common.S */
@@ -175,7 +178,8 @@ extern int vfp_restore_user_hwstate(struct user_vfp *,
 /*
  * Change these and you break ASM code in entry-common.S
  */
-#define _TIF_WORK_MASK		(_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
+#define _TIF_WORK_MASK		(_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY | \
+				 _TIF_SIGPENDING | \
 				 _TIF_NOTIFY_RESUME | _TIF_UPROBE | \
 				 _TIF_NOTIFY_SIGNAL)
 
diff --git a/arch/arm/kernel/asm-offsets.c b/arch/arm/kernel/asm-offsets.c
index 645845e4982a6..73e321c6d1525 100644
--- a/arch/arm/kernel/asm-offsets.c
+++ b/arch/arm/kernel/asm-offsets.c
@@ -43,6 +43,7 @@ int main(void)
   BLANK();
   DEFINE(TI_FLAGS,		offsetof(struct thread_info, flags));
   DEFINE(TI_PREEMPT,		offsetof(struct thread_info, preempt_count));
+  DEFINE(TI_PREEMPT_LAZY,	offsetof(struct thread_info, preempt_lazy_count));
 #ifndef CONFIG_THREAD_INFO_IN_TASK
   DEFINE(TI_TASK,		offsetof(struct thread_info, task));
 #endif
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 5cd057859fe90..4db90d80d175f 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -203,11 +203,18 @@ ENDPROC(__dabt_svc)
 
 #ifdef CONFIG_PREEMPTION
 	ldr	r8, [tsk, #TI_PREEMPT]		@ get preempt count
-	ldr	r0, [tsk, #TI_FLAGS]		@ get flags
 	teq	r8, #0				@ if preempt count != 0
+	bne	1f				@ return from exeption
+	ldr	r0, [tsk, #TI_FLAGS]		@ get flags
+	tst	r0, #_TIF_NEED_RESCHED		@ if NEED_RESCHED is set
+	blne	svc_preempt			@ preempt!
+
+	ldr	r8, [tsk, #TI_PREEMPT_LAZY]	@ get preempt lazy count
+	teq	r8, #0				@ if preempt lazy count != 0
 	movne	r0, #0				@ force flags to 0
-	tst	r0, #_TIF_NEED_RESCHED
+	tst	r0, #_TIF_NEED_RESCHED_LAZY
 	blne	svc_preempt
+1:
 #endif
 
 	svc_exit r5, irq = 1			@ return from exception
@@ -222,8 +229,14 @@ ENDPROC(__irq_svc)
 1:	bl	preempt_schedule_irq		@ irq en/disable is done inside
 	ldr	r0, [tsk, #TI_FLAGS]		@ get new tasks TI_FLAGS
 	tst	r0, #_TIF_NEED_RESCHED
+	bne	1b
+	tst	r0, #_TIF_NEED_RESCHED_LAZY
 	reteq	r8				@ go again
-	b	1b
+	ldr	r0, [tsk, #TI_PREEMPT_LAZY]	@ get preempt lazy count
+	teq	r0, #0				@ if preempt lazy count != 0
+	beq	1b
+	ret	r8				@ go again
+
 #endif
 
 __und_fault:
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index c532a60410667..f4292cc5d13b4 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -607,7 +607,8 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
 	 */
 	trace_hardirqs_off();
 	do {
-		if (likely(thread_flags & _TIF_NEED_RESCHED)) {
+		if (likely(thread_flags & (_TIF_NEED_RESCHED |
+					   _TIF_NEED_RESCHED_LAZY))) {
 			schedule();
 		} else {
 			if (unlikely(!user_mode(regs)))
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index a062e07516dd2..3a609dbacd8a7 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -417,6 +417,9 @@ do_translation_fault(unsigned long addr, unsigned int fsr,
 	if (addr < TASK_SIZE)
 		return do_page_fault(addr, fsr, regs);
 
+	if (interrupts_enabled(regs))
+		local_irq_enable();
+
 	if (user_mode(regs))
 		goto bad_area;
 
@@ -487,6 +490,9 @@ do_translation_fault(unsigned long addr, unsigned int fsr,
 static int
 do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 {
+	if (interrupts_enabled(regs))
+		local_irq_enable();
+
 	do_bad_area(addr, fsr, regs);
 	return 0;
 }
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index f2b5a4abef215..58d5e84200fe7 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -89,6 +89,7 @@ config ARM64
 	select ARCH_SUPPORTS_ATOMIC_RMW
 	select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
 	select ARCH_SUPPORTS_NUMA_BALANCING
+	select ARCH_SUPPORTS_RT
 	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION if COMPAT
 	select ARCH_WANT_DEFAULT_BPF_JIT
 	select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
@@ -193,6 +194,7 @@ config ARM64
 	select HAVE_PERF_REGS
 	select HAVE_PERF_USER_STACK_DUMP
 	select HAVE_REGS_AND_STACK_ACCESS_API
+	select HAVE_PREEMPT_LAZY
 	select HAVE_POSIX_CPU_TIMERS_TASK_WORK
 	select HAVE_FUNCTION_ARG_ACCESS_API
 	select MMU_GATHER_RCU_TABLE_FREE
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index c4ba047a82d26..3caf6346ea95f 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -1001,7 +1001,8 @@ static inline void update_mmu_cache(struct vm_area_struct *vma,
  */
 static inline bool arch_faults_on_old_pte(void)
 {
-	WARN_ON(preemptible());
+	/* The register read below requires a stable CPU to make any sense */
+	cant_migrate();
 
 	return !cpu_has_hw_af();
 }
diff --git a/arch/arm64/include/asm/preempt.h b/arch/arm64/include/asm/preempt.h
index e83f0982b99c1..2545c17281e1c 100644
--- a/arch/arm64/include/asm/preempt.h
+++ b/arch/arm64/include/asm/preempt.h
@@ -70,13 +70,36 @@ static inline bool __preempt_count_dec_and_test(void)
 	 * interrupt occurring between the non-atomic READ_ONCE/WRITE_ONCE
 	 * pair.
 	 */
-	return !pc || !READ_ONCE(ti->preempt_count);
+	if (!pc || !READ_ONCE(ti->preempt_count))
+		return true;
+#ifdef CONFIG_PREEMPT_LAZY
+	if ((pc & ~PREEMPT_NEED_RESCHED))
+		return false;
+	if (current_thread_info()->preempt_lazy_count)
+		return false;
+	return test_thread_flag(TIF_NEED_RESCHED_LAZY);
+#else
+	return false;
+#endif
 }
 
 static inline bool should_resched(int preempt_offset)
 {
+#ifdef CONFIG_PREEMPT_LAZY
+	u64 pc = READ_ONCE(current_thread_info()->preempt_count);
+	if (pc == preempt_offset)
+		return true;
+
+	if ((pc & ~PREEMPT_NEED_RESCHED) != preempt_offset)
+		return false;
+
+	if (current_thread_info()->preempt_lazy_count)
+		return false;
+	return test_thread_flag(TIF_NEED_RESCHED_LAZY);
+#else
 	u64 pc = READ_ONCE(current_thread_info()->preempt_count);
 	return pc == preempt_offset;
+#endif
 }
 
 #ifdef CONFIG_PREEMPTION
diff --git a/arch/arm64/include/asm/signal.h b/arch/arm64/include/asm/signal.h
index ef449f5f4ba80..5e535c3e49260 100644
--- a/arch/arm64/include/asm/signal.h
+++ b/arch/arm64/include/asm/signal.h
@@ -22,4 +22,8 @@ static inline void __user *arch_untagged_si_addr(void __user *addr,
 }
 #define arch_untagged_si_addr arch_untagged_si_addr
 
+#if defined(CONFIG_PREEMPT_RT)
+#define ARCH_RT_DELAYS_SIGNAL_SEND
+#endif
+
 #endif
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index e1317b7c45251..861594d9662df 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -26,6 +26,7 @@ struct thread_info {
 #ifdef CONFIG_ARM64_SW_TTBR0_PAN
 	u64			ttbr0;		/* saved TTBR0_EL1 */
 #endif
+	int			preempt_lazy_count;	/* 0 => preemptable, <0 => bug */
 	union {
 		u64		preempt_count;	/* 0 => preemptible, <0 => bug */
 		struct {
@@ -68,6 +69,7 @@ int arch_dup_task_struct(struct task_struct *dst,
 #define TIF_UPROBE		4	/* uprobe breakpoint or singlestep */
 #define TIF_MTE_ASYNC_FAULT	5	/* MTE Asynchronous Tag Check Fault */
 #define TIF_NOTIFY_SIGNAL	6	/* signal notifications exist */
+#define TIF_NEED_RESCHED_LAZY	7
 #define TIF_SYSCALL_TRACE	8	/* syscall trace active */
 #define TIF_SYSCALL_AUDIT	9	/* syscall auditing */
 #define TIF_SYSCALL_TRACEPOINT	10	/* syscall tracepoint for ftrace */
@@ -98,8 +100,10 @@ int arch_dup_task_struct(struct task_struct *dst,
 #define _TIF_SVE		(1 << TIF_SVE)
 #define _TIF_MTE_ASYNC_FAULT	(1 << TIF_MTE_ASYNC_FAULT)
 #define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
+#define _TIF_NEED_RESCHED_LAZY	(1 << TIF_NEED_RESCHED_LAZY)
 
-#define _TIF_WORK_MASK		(_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
+#define _TIF_WORK_MASK		(_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY | \
+				 _TIF_SIGPENDING | \
 				 _TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE | \
 				 _TIF_UPROBE | _TIF_MTE_ASYNC_FAULT | \
 				 _TIF_NOTIFY_SIGNAL)
@@ -108,6 +112,8 @@ int arch_dup_task_struct(struct task_struct *dst,
 				 _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP | \
 				 _TIF_SYSCALL_EMU)
 
+#define _TIF_NEED_RESCHED_MASK	(_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY)
+
 #ifdef CONFIG_SHADOW_CALL_STACK
 #define INIT_SCS							\
 	.scs_base	= init_shadow_call_stack,			\
diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index 1197e7679882e..e74c0415f67ea 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -32,6 +32,7 @@ int main(void)
   DEFINE(TSK_TI_CPU,		offsetof(struct task_struct, thread_info.cpu));
   DEFINE(TSK_TI_FLAGS,		offsetof(struct task_struct, thread_info.flags));
   DEFINE(TSK_TI_PREEMPT,	offsetof(struct task_struct, thread_info.preempt_count));
+  DEFINE(TSK_TI_PREEMPT_LAZY,	offsetof(struct task_struct, thread_info.preempt_lazy_count));
 #ifdef CONFIG_ARM64_SW_TTBR0_PAN
   DEFINE(TSK_TI_TTBR0,		offsetof(struct task_struct, thread_info.ttbr0));
 #endif
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 5280e098cfb5d..a246a26ef5d66 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -206,10 +206,19 @@ static void __get_cpu_fpsimd_context(void)
  *
  * The double-underscore version must only be called if you know the task
  * can't be preempted.
+ *
+ * On RT kernels local_bh_disable() is not sufficient because it only
+ * serializes soft interrupt related sections via a local lock, but stays
+ * preemptible. Disabling preemption is the right choice here as bottom
+ * half processing is always in thread context on RT kernels so it
+ * implicitly prevents bottom half processing as well.
  */
 static void get_cpu_fpsimd_context(void)
 {
-	local_bh_disable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_bh_disable();
+	else
+		preempt_disable();
 	__get_cpu_fpsimd_context();
 }
 
@@ -230,7 +239,10 @@ static void __put_cpu_fpsimd_context(void)
 static void put_cpu_fpsimd_context(void)
 {
 	__put_cpu_fpsimd_context();
-	local_bh_enable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_bh_enable();
+	else
+		preempt_enable();
 }
 
 static bool have_cpu_fpsimd_context(void)
@@ -1135,6 +1147,8 @@ static void fpsimd_flush_thread_vl(enum vec_type type)
 
 void fpsimd_flush_thread(void)
 {
+	void *sve_state = NULL;
+
 	if (!system_supports_fpsimd())
 		return;
 
@@ -1146,11 +1160,16 @@ void fpsimd_flush_thread(void)
 
 	if (system_supports_sve()) {
 		clear_thread_flag(TIF_SVE);
-		sve_free(current);
+
+		/* Defer kfree() while in atomic context */
+		sve_state = current->thread.sve_state;
+		current->thread.sve_state = NULL;
+
 		fpsimd_flush_thread_vl(ARM64_VEC_SVE);
 	}
 
 	put_cpu_fpsimd_context();
+	kfree(sve_state);
 }
 
 /*
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index d8aaf4b6f4320..3c0abbe904268 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -920,7 +920,7 @@ static void do_signal(struct pt_regs *regs)
 void do_notify_resume(struct pt_regs *regs, unsigned long thread_flags)
 {
 	do {
-		if (thread_flags & _TIF_NEED_RESCHED) {
+		if (thread_flags & _TIF_NEED_RESCHED_MASK) {
 			/* Unmask Debug and SError for the next task */
 			local_daif_restore(DAIF_PROCCTX_NOIRQ);
 
@@ -928,6 +928,14 @@ void do_notify_resume(struct pt_regs *regs, unsigned long thread_flags)
 		} else {
 			local_daif_restore(DAIF_PROCCTX);
 
+#ifdef ARCH_RT_DELAYS_SIGNAL_SEND
+			if (unlikely(current->forced_info.si_signo)) {
+				struct task_struct *t = current;
+				force_sig_info(&t->forced_info);
+				t->forced_info.si_signo = 0;
+			}
+#endif
+
 			if (thread_flags & _TIF_UPROBE)
 				uprobe_notify_resume(regs);
 
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index a4a0063df456c..77e3b06ec5185 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -846,7 +846,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 		 * involves poking the GIC, which must be done in a
 		 * non-preemptible context.
 		 */
-		preempt_disable();
+		migrate_disable();
 
 		kvm_pmu_flush_hwstate(vcpu);
 
@@ -870,7 +870,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 				kvm_timer_sync_user(vcpu);
 			kvm_vgic_sync_hwstate(vcpu);
 			local_irq_enable();
-			preempt_enable();
+			migrate_enable();
 			continue;
 		}
 
@@ -943,7 +943,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 		/* Exit types that need handling before we can be preempted */
 		handle_exit_early(vcpu, ret);
 
-		preempt_enable();
+		migrate_enable();
 
 		/*
 		 * The ARMv8 architecture doesn't give the hypervisor
diff --git a/arch/ia64/include/asm/thread_info.h b/arch/ia64/include/asm/thread_info.h
index 51d20cb377062..1684716f08201 100644
--- a/arch/ia64/include/asm/thread_info.h
+++ b/arch/ia64/include/asm/thread_info.h
@@ -55,15 +55,15 @@ struct thread_info {
 #ifndef ASM_OFFSETS_C
 /* how to get the thread information struct from C */
 #define current_thread_info()	((struct thread_info *) ((char *) current + IA64_TASK_SIZE))
-#define alloc_thread_stack_node(tsk, node)	\
+#define arch_alloc_thread_stack_node(tsk, node)	\
 		((unsigned long *) ((char *) (tsk) + IA64_TASK_SIZE))
 #define task_thread_info(tsk)	((struct thread_info *) ((char *) (tsk) + IA64_TASK_SIZE))
 #else
 #define current_thread_info()	((struct thread_info *) 0)
-#define alloc_thread_stack_node(tsk, node)	((unsigned long *) 0)
+#define arch_alloc_thread_stack_node(tsk, node)	((unsigned long *) 0)
 #define task_thread_info(tsk)	((struct thread_info *) 0)
 #endif
-#define free_thread_stack(tsk)	/* nothing */
+#define arch_free_thread_stack(tsk)	/* nothing */
 #define task_stack_page(tsk)	((void *)(tsk))
 
 #define __HAVE_THREAD_FUNCTIONS
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index b779603978e10..fa5e28a8e6be4 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -144,6 +144,7 @@ config PPC
 	select ARCH_STACKWALK
 	select ARCH_SUPPORTS_ATOMIC_RMW
 	select ARCH_SUPPORTS_DEBUG_PAGEALLOC	if PPC_BOOK3S || PPC_8xx || 40x
+	select ARCH_SUPPORTS_RT			if HAVE_POSIX_CPU_TIMERS_TASK_WORK
 	select ARCH_USE_BUILTIN_BSWAP
 	select ARCH_USE_CMPXCHG_LOCKREF		if PPC64
 	select ARCH_USE_MEMTEST
@@ -213,6 +214,7 @@ config PPC
 	select HAVE_IOREMAP_PROT
 	select HAVE_IRQ_EXIT_ON_IRQ_STACK
 	select HAVE_IRQ_TIME_ACCOUNTING
+	select HAVE_POSIX_CPU_TIMERS_TASK_WORK	if !KVM
 	select HAVE_KERNEL_GZIP
 	select HAVE_KERNEL_LZMA			if DEFAULT_UIMAGE
 	select HAVE_KERNEL_LZO			if DEFAULT_UIMAGE
@@ -229,6 +231,7 @@ config PPC
 	select HAVE_PERF_EVENTS_NMI		if PPC64
 	select HAVE_PERF_REGS
 	select HAVE_PERF_USER_STACK_DUMP
+	select HAVE_PREEMPT_LAZY
 	select HAVE_REGS_AND_STACK_ACCESS_API
 	select HAVE_RELIABLE_STACKTRACE
 	select HAVE_RSEQ
diff --git a/arch/powerpc/include/asm/stackprotector.h b/arch/powerpc/include/asm/stackprotector.h
index 1c8460e235838..b1653c160bab9 100644
--- a/arch/powerpc/include/asm/stackprotector.h
+++ b/arch/powerpc/include/asm/stackprotector.h
@@ -24,7 +24,11 @@ static __always_inline void boot_init_stack_canary(void)
 	unsigned long canary;
 
 	/* Try to get a semi random initial value. */
+#ifdef CONFIG_PREEMPT_RT
+	canary = (unsigned long)&canary;
+#else
 	canary = get_random_canary();
+#endif
 	canary ^= mftb();
 	canary ^= LINUX_VERSION_CODE;
 	canary &= CANARY_MASK;
diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h
index d6e649b3c70b6..ba5abdc26f94e 100644
--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h
@@ -47,6 +47,8 @@
 struct thread_info {
 	int		preempt_count;		/* 0 => preemptable,
 						   <0 => BUG */
+	int		preempt_lazy_count;	/* 0 => preemptable,
+						   <0 => BUG */
 #ifdef CONFIG_SMP
 	unsigned int	cpu;
 #endif
@@ -71,6 +73,7 @@ struct thread_info {
 #define INIT_THREAD_INFO(tsk)			\
 {						\
 	.preempt_count = INIT_PREEMPT_COUNT,	\
+	.preempt_lazy_count = 0,		\
 	.flags =	0,			\
 }
 
@@ -96,6 +99,7 @@ void arch_setup_new_exec(void);
 #define TIF_PATCH_PENDING	6	/* pending live patching update */
 #define TIF_SYSCALL_AUDIT	7	/* syscall auditing active */
 #define TIF_SINGLESTEP		8	/* singlestepping active */
+#define TIF_NEED_RESCHED_LAZY	9	/* lazy rescheduling necessary */
 #define TIF_SECCOMP		10	/* secure computing */
 #define TIF_RESTOREALL		11	/* Restore all regs (implies NOERROR) */
 #define TIF_NOERROR		12	/* Force successful syscall return */
@@ -111,6 +115,7 @@ void arch_setup_new_exec(void);
 #define TIF_POLLING_NRFLAG	19	/* true if poll_idle() is polling TIF_NEED_RESCHED */
 #define TIF_32BIT		20	/* 32 bit binary */
 
+
 /* as above, but as bit values */
 #define _TIF_SYSCALL_TRACE	(1<<TIF_SYSCALL_TRACE)
 #define _TIF_SIGPENDING		(1<<TIF_SIGPENDING)
@@ -122,6 +127,7 @@ void arch_setup_new_exec(void);
 #define _TIF_PATCH_PENDING	(1<<TIF_PATCH_PENDING)
 #define _TIF_SYSCALL_AUDIT	(1<<TIF_SYSCALL_AUDIT)
 #define _TIF_SINGLESTEP		(1<<TIF_SINGLESTEP)
+#define _TIF_NEED_RESCHED_LAZY	(1<<TIF_NEED_RESCHED_LAZY)
 #define _TIF_SECCOMP		(1<<TIF_SECCOMP)
 #define _TIF_RESTOREALL		(1<<TIF_RESTOREALL)
 #define _TIF_NOERROR		(1<<TIF_NOERROR)
@@ -135,10 +141,12 @@ void arch_setup_new_exec(void);
 				 _TIF_SYSCALL_EMU)
 
 #define _TIF_USER_WORK_MASK	(_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
+				 _TIF_NEED_RESCHED_LAZY | \
 				 _TIF_NOTIFY_RESUME | _TIF_UPROBE | \
 				 _TIF_RESTORE_TM | _TIF_PATCH_PENDING | \
 				 _TIF_NOTIFY_SIGNAL)
 #define _TIF_PERSYSCALL_MASK	(_TIF_RESTOREALL|_TIF_NOERROR)
+#define _TIF_NEED_RESCHED_MASK	(_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY)
 
 /* Bits in local_flags */
 /* Don't move TLF_NAPPING without adjusting the code in entry_32.S */
diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c
index 7cd6ce3ec4231..cdb465301e6e9 100644
--- a/arch/powerpc/kernel/interrupt.c
+++ b/arch/powerpc/kernel/interrupt.c
@@ -346,7 +346,7 @@ interrupt_exit_user_prepare_main(unsigned long ret, struct pt_regs *regs)
 	ti_flags = read_thread_flags();
 	while (unlikely(ti_flags & (_TIF_USER_WORK_MASK & ~_TIF_RESTORE_TM))) {
 		local_irq_enable();
-		if (ti_flags & _TIF_NEED_RESCHED) {
+		if (ti_flags & _TIF_NEED_RESCHED_MASK) {
 			schedule();
 		} else {
 			/*
@@ -550,11 +550,15 @@ notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs)
 		/* Returning to a kernel context with local irqs enabled. */
 		WARN_ON_ONCE(!(regs->msr & MSR_EE));
 again:
-		if (IS_ENABLED(CONFIG_PREEMPT)) {
+		if (IS_ENABLED(CONFIG_PREEMPTION)) {
 			/* Return to preemptible kernel context */
 			if (unlikely(read_thread_flags() & _TIF_NEED_RESCHED)) {
 				if (preempt_count() == 0)
 					preempt_schedule_irq();
+			} else if (unlikely(current_thread_info()->flags & _TIF_NEED_RESCHED_LAZY)) {
+				if ((preempt_count() == 0) &&
+				    (current_thread_info()->preempt_lazy_count == 0))
+					preempt_schedule_irq();
 			}
 		}
 
diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 2cf31a97126ce..94cb5fe50415b 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -690,6 +690,7 @@ static inline void check_stack_overflow(void)
 	}
 }
 
+#ifndef CONFIG_PREEMPT_RT
 static __always_inline void call_do_softirq(const void *sp)
 {
 	/* Temporarily switch r1 to sp, call __do_softirq() then restore r1. */
@@ -708,6 +709,7 @@ static __always_inline void call_do_softirq(const void *sp)
 		   "r11", "r12"
 	);
 }
+#endif
 
 static __always_inline void call_do_irq(struct pt_regs *regs, void *sp)
 {
@@ -821,10 +823,12 @@ void *mcheckirq_ctx[NR_CPUS] __read_mostly;
 void *softirq_ctx[NR_CPUS] __read_mostly;
 void *hardirq_ctx[NR_CPUS] __read_mostly;
 
+#ifndef CONFIG_PREEMPT_RT
 void do_softirq_own_stack(void)
 {
 	call_do_softirq(softirq_ctx[smp_processor_id()]);
 }
+#endif
 
 irq_hw_number_t virq_to_hw(unsigned int virq)
 {
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index a08bb7cefdc54..ae34f68eedc19 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -260,12 +260,17 @@ static char *get_mmu_str(void)
 
 static int __die(const char *str, struct pt_regs *regs, long err)
 {
+	const char *pr = "";
+
 	printk("Oops: %s, sig: %ld [#%d]\n", str, err, ++die_counter);
 
+	if (IS_ENABLED(CONFIG_PREEMPTION))
+		pr = IS_ENABLED(CONFIG_PREEMPT_RT) ? " PREEMPT_RT" : " PREEMPT";
+
 	printk("%s PAGE_SIZE=%luK%s%s%s%s%s%s %s\n",
 	       IS_ENABLED(CONFIG_CPU_LITTLE_ENDIAN) ? "LE" : "BE",
 	       PAGE_SIZE / 1024, get_mmu_str(),
-	       IS_ENABLED(CONFIG_PREEMPT) ? " PREEMPT" : "",
+	       pr,
 	       IS_ENABLED(CONFIG_SMP) ? " SMP" : "",
 	       IS_ENABLED(CONFIG_SMP) ? (" NR_CPUS=" __stringify(NR_CPUS)) : "",
 	       debug_pagealloc_enabled() ? " DEBUG_PAGEALLOC" : "",
diff --git a/arch/powerpc/kvm/Kconfig b/arch/powerpc/kvm/Kconfig
index 18e58085447cb..3828090785e0f 100644
--- a/arch/powerpc/kvm/Kconfig
+++ b/arch/powerpc/kvm/Kconfig
@@ -195,6 +195,7 @@ config KVM_E500MC
 config KVM_MPIC
 	bool "KVM in-kernel MPIC emulation"
 	depends on KVM && E500
+	depends on !PREEMPT_RT
 	select HAVE_KVM_IRQCHIP
 	select HAVE_KVM_IRQFD
 	select HAVE_KVM_IRQ_ROUTING
diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index 4d991cf840d91..e620cefcce6a1 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -24,6 +24,7 @@
 #include <linux/of.h>
 #include <linux/iommu.h>
 #include <linux/rculist.h>
+#include <linux/local_lock.h>
 #include <asm/io.h>
 #include <asm/prom.h>
 #include <asm/rtas.h>
@@ -195,7 +196,13 @@ static int tce_build_pSeriesLP(unsigned long liobn, long tcenum, long tceshift,
 	return ret;
 }
 
-static DEFINE_PER_CPU(__be64 *, tce_page);
+struct tce_page {
+	__be64 * page;
+	local_lock_t lock;
+};
+static DEFINE_PER_CPU(struct tce_page, tce_page) = {
+	.lock = INIT_LOCAL_LOCK(lock),
+};
 
 static int tce_buildmulti_pSeriesLP(struct iommu_table *tbl, long tcenum,
 				     long npages, unsigned long uaddr,
@@ -218,9 +225,10 @@ static int tce_buildmulti_pSeriesLP(struct iommu_table *tbl, long tcenum,
 		                           direction, attrs);
 	}
 
-	local_irq_save(flags);	/* to protect tcep and the page behind it */
+	/* to protect tcep and the page behind it */
+	local_lock_irqsave(&tce_page.lock, flags);
 
-	tcep = __this_cpu_read(tce_page);
+	tcep = __this_cpu_read(tce_page.page);
 
 	/* This is safe to do since interrupts are off when we're called
 	 * from iommu_alloc{,_sg}()
@@ -229,12 +237,12 @@ static int tce_buildmulti_pSeriesLP(struct iommu_table *tbl, long tcenum,
 		tcep = (__be64 *)__get_free_page(GFP_ATOMIC);
 		/* If allocation fails, fall back to the loop implementation */
 		if (!tcep) {
-			local_irq_restore(flags);
+			local_unlock_irqrestore(&tce_page.lock, flags);
 			return tce_build_pSeriesLP(tbl->it_index, tcenum,
 					tceshift,
 					npages, uaddr, direction, attrs);
 		}
-		__this_cpu_write(tce_page, tcep);
+		__this_cpu_write(tce_page.page, tcep);
 	}
 
 	rpn = __pa(uaddr) >> tceshift;
@@ -264,7 +272,7 @@ static int tce_buildmulti_pSeriesLP(struct iommu_table *tbl, long tcenum,
 		tcenum += limit;
 	} while (npages > 0 && !rc);
 
-	local_irq_restore(flags);
+	local_unlock_irqrestore(&tce_page.lock, flags);
 
 	if (unlikely(rc == H_NOT_ENOUGH_RESOURCES)) {
 		ret = (int)rc;
@@ -440,16 +448,17 @@ static int tce_setrange_multi_pSeriesLP(unsigned long start_pfn,
 				DMA_BIDIRECTIONAL, 0);
 	}
 
-	local_irq_disable();	/* to protect tcep and the page behind it */
-	tcep = __this_cpu_read(tce_page);
+	/* to protect tcep and the page behind it */
+	local_lock_irq(&tce_page.lock);
+	tcep = __this_cpu_read(tce_page.page);
 
 	if (!tcep) {
 		tcep = (__be64 *)__get_free_page(GFP_ATOMIC);
 		if (!tcep) {
-			local_irq_enable();
+			local_unlock_irq(&tce_page.lock);
 			return -ENOMEM;
 		}
-		__this_cpu_write(tce_page, tcep);
+		__this_cpu_write(tce_page.page, tcep);
 	}
 
 	proto_tce = TCE_PCI_READ | TCE_PCI_WRITE;
@@ -492,7 +501,7 @@ static int tce_setrange_multi_pSeriesLP(unsigned long start_pfn,
 
 	/* error cleanup: caller will clear whole range */
 
-	local_irq_enable();
+	local_unlock_irq(&tce_page.lock);
 	return rc;
 }
 
diff --git a/arch/sh/kernel/irq.c b/arch/sh/kernel/irq.c
index ef0f0827cf575..2d3eca8fee011 100644
--- a/arch/sh/kernel/irq.c
+++ b/arch/sh/kernel/irq.c
@@ -149,6 +149,7 @@ void irq_ctx_exit(int cpu)
 	hardirq_ctx[cpu] = NULL;
 }
 
+#ifndef CONFIG_PREEMPT_RT
 void do_softirq_own_stack(void)
 {
 	struct thread_info *curctx;
@@ -176,6 +177,7 @@ void do_softirq_own_stack(void)
 		  "r5", "r6", "r7", "r8", "r9", "r15", "t", "pr"
 	);
 }
+#endif
 #else
 static inline void handle_one_irq(unsigned int irq)
 {
diff --git a/arch/sparc/kernel/irq_64.c b/arch/sparc/kernel/irq_64.c
index c8848bb681a11..41fa1be980a33 100644
--- a/arch/sparc/kernel/irq_64.c
+++ b/arch/sparc/kernel/irq_64.c
@@ -855,6 +855,7 @@ void __irq_entry handler_irq(int pil, struct pt_regs *regs)
 	set_irq_regs(old_regs);
 }
 
+#ifndef CONFIG_PREEMPT_RT
 void do_softirq_own_stack(void)
 {
 	void *orig_sp, *sp = softirq_stack[smp_processor_id()];
@@ -869,6 +870,7 @@ void do_softirq_own_stack(void)
 	__asm__ __volatile__("mov %0, %%sp"
 			     : : "r" (orig_sp));
 }
+#endif
 
 #ifdef CONFIG_HOTPLUG_CPU
 void fixup_irqs(void)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 9f5bd41bf660c..587aa9de2ba8f 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -109,6 +109,7 @@ config X86
 	select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP	if NR_CPUS <= 4096
 	select ARCH_SUPPORTS_LTO_CLANG
 	select ARCH_SUPPORTS_LTO_CLANG_THIN
+	select ARCH_SUPPORTS_RT
 	select ARCH_USE_BUILTIN_BSWAP
 	select ARCH_USE_MEMTEST
 	select ARCH_USE_QUEUED_RWLOCKS
@@ -235,6 +236,7 @@ config X86
 	select HAVE_PCI
 	select HAVE_PERF_REGS
 	select HAVE_PERF_USER_STACK_DUMP
+	select HAVE_PREEMPT_LAZY
 	select MMU_GATHER_RCU_TABLE_FREE		if PARAVIRT
 	select HAVE_POSIX_CPU_TIMERS_TASK_WORK
 	select HAVE_REGS_AND_STACK_ACCESS_API
diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h
index fe5efbcba8240..ab8cb5fc2329e 100644
--- a/arch/x86/include/asm/preempt.h
+++ b/arch/x86/include/asm/preempt.h
@@ -90,17 +90,48 @@ static __always_inline void __preempt_count_sub(int val)
  * a decrement which hits zero means we have no preempt_count and should
  * reschedule.
  */
-static __always_inline bool __preempt_count_dec_and_test(void)
+static __always_inline bool ____preempt_count_dec_and_test(void)
 {
 	return GEN_UNARY_RMWcc("decl", __preempt_count, e, __percpu_arg([var]));
 }
 
+static __always_inline bool __preempt_count_dec_and_test(void)
+{
+	if (____preempt_count_dec_and_test())
+		return true;
+#ifdef CONFIG_PREEMPT_LAZY
+	if (preempt_count())
+		return false;
+	if (current_thread_info()->preempt_lazy_count)
+		return false;
+	return test_thread_flag(TIF_NEED_RESCHED_LAZY);
+#else
+	return false;
+#endif
+}
+
 /*
  * Returns true when we need to resched and can (barring IRQ state).
  */
 static __always_inline bool should_resched(int preempt_offset)
 {
+#ifdef CONFIG_PREEMPT_LAZY
+	u32 tmp;
+	tmp = raw_cpu_read_4(__preempt_count);
+	if (tmp == preempt_offset)
+		return true;
+
+	/* preempt count == 0 ? */
+	tmp &= ~PREEMPT_NEED_RESCHED;
+	if (tmp != preempt_offset)
+		return false;
+	/* XXX PREEMPT_LOCK_OFFSET */
+	if (current_thread_info()->preempt_lazy_count)
+		return false;
+	return test_thread_flag(TIF_NEED_RESCHED_LAZY);
+#else
 	return unlikely(raw_cpu_read_4(__preempt_count) == preempt_offset);
+#endif
 }
 
 #ifdef CONFIG_PREEMPTION
diff --git a/arch/x86/include/asm/signal.h b/arch/x86/include/asm/signal.h
index 2dfb5fea13aff..fc03f4f7ed84c 100644
--- a/arch/x86/include/asm/signal.h
+++ b/arch/x86/include/asm/signal.h
@@ -28,6 +28,19 @@ typedef struct {
 #define SA_IA32_ABI	0x02000000u
 #define SA_X32_ABI	0x01000000u
 
+/*
+ * Because some traps use the IST stack, we must keep preemption
+ * disabled while calling do_trap(), but do_trap() may call
+ * force_sig_info() which will grab the signal spin_locks for the
+ * task, which in PREEMPT_RT are mutexes.  By defining
+ * ARCH_RT_DELAYS_SIGNAL_SEND the force_sig_info() will set
+ * TIF_NOTIFY_RESUME and set up the signal to be sent on exit of the
+ * trap.
+ */
+#if defined(CONFIG_PREEMPT_RT)
+#define ARCH_RT_DELAYS_SIGNAL_SEND
+#endif
+
 #ifndef CONFIG_COMPAT
 #define compat_sigset_t compat_sigset_t
 typedef sigset_t compat_sigset_t;
diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index ebec69c35e951..39005bff5b8f3 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -57,6 +57,8 @@ struct thread_info {
 	unsigned long		flags;		/* low level flags */
 	unsigned long		syscall_work;	/* SYSCALL_WORK_ flags */
 	u32			status;		/* thread synchronous flags */
+	int			preempt_lazy_count;	/* 0 => lazy preemptable
+							  <0 => BUG */
 #ifdef CONFIG_SMP
 	u32			cpu;		/* current CPU */
 #endif
@@ -65,6 +67,7 @@ struct thread_info {
 #define INIT_THREAD_INFO(tsk)			\
 {						\
 	.flags		= 0,			\
+	.preempt_lazy_count	= 0,		\
 }
 
 #else /* !__ASSEMBLY__ */
@@ -93,6 +96,7 @@ struct thread_info {
 #define TIF_NOTSC		16	/* TSC is not accessible in userland */
 #define TIF_NOTIFY_SIGNAL	17	/* signal notifications exist */
 #define TIF_SLD			18	/* Restore split lock detection on context switch */
+#define TIF_NEED_RESCHED_LAZY	19	/* lazy rescheduling necessary */
 #define TIF_MEMDIE		20	/* is terminating due to OOM killer */
 #define TIF_POLLING_NRFLAG	21	/* idle is polling for TIF_NEED_RESCHED */
 #define TIF_IO_BITMAP		22	/* uses I/O bitmap */
@@ -117,6 +121,7 @@ struct thread_info {
 #define _TIF_NOTSC		(1 << TIF_NOTSC)
 #define _TIF_NOTIFY_SIGNAL	(1 << TIF_NOTIFY_SIGNAL)
 #define _TIF_SLD		(1 << TIF_SLD)
+#define _TIF_NEED_RESCHED_LAZY	(1 << TIF_NEED_RESCHED_LAZY)
 #define _TIF_POLLING_NRFLAG	(1 << TIF_POLLING_NRFLAG)
 #define _TIF_IO_BITMAP		(1 << TIF_IO_BITMAP)
 #define _TIF_SPEC_FORCE_UPDATE	(1 << TIF_SPEC_FORCE_UPDATE)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 74b53a16f38a7..5736c904d3c5e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8811,6 +8811,12 @@ int kvm_arch_init(void *opaque)
 		goto out;
 	}
 
+	if (IS_ENABLED(CONFIG_PREEMPT_RT) && !boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) {
+		pr_err("RT requires X86_FEATURE_CONSTANT_TSC\n");
+		r = -EOPNOTSUPP;
+		goto out;
+	}
+
 	r = -ENOMEM;
 
 	x86_emulator_cache = kvm_alloc_emulator_cache();
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 1adfe4824ef5e..689e12dd4562e 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2040,14 +2040,14 @@ static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,
 		return;
 
 	if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
-		int cpu = get_cpu();
+		int cpu = get_cpu_light();
 		if (cpumask_test_cpu(cpu, hctx->cpumask)) {
 			__blk_mq_run_hw_queue(hctx);
-			put_cpu();
+			put_cpu_light();
 			return;
 		}
 
-		put_cpu();
+		put_cpu_light();
 	}
 
 	kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work,
diff --git a/crypto/cryptd.c b/crypto/cryptd.c
index a1bea0f4baa88..5f8ca8c1f59cd 100644
--- a/crypto/cryptd.c
+++ b/crypto/cryptd.c
@@ -36,6 +36,7 @@ static struct workqueue_struct *cryptd_wq;
 struct cryptd_cpu_queue {
 	struct crypto_queue queue;
 	struct work_struct work;
+	spinlock_t qlock;
 };
 
 struct cryptd_queue {
@@ -105,6 +106,7 @@ static int cryptd_init_queue(struct cryptd_queue *queue,
 		cpu_queue = per_cpu_ptr(queue->cpu_queue, cpu);
 		crypto_init_queue(&cpu_queue->queue, max_cpu_qlen);
 		INIT_WORK(&cpu_queue->work, cryptd_queue_worker);
+		spin_lock_init(&cpu_queue->qlock);
 	}
 	pr_info("cryptd: max_cpu_qlen set to %d\n", max_cpu_qlen);
 	return 0;
@@ -129,8 +131,10 @@ static int cryptd_enqueue_request(struct cryptd_queue *queue,
 	struct cryptd_cpu_queue *cpu_queue;
 	refcount_t *refcnt;
 
-	cpu = get_cpu();
-	cpu_queue = this_cpu_ptr(queue->cpu_queue);
+	cpu_queue = raw_cpu_ptr(queue->cpu_queue);
+	spin_lock_bh(&cpu_queue->qlock);
+	cpu = smp_processor_id();
+
 	err = crypto_enqueue_request(&cpu_queue->queue, request);
 
 	refcnt = crypto_tfm_ctx(request->tfm);
@@ -146,7 +150,7 @@ static int cryptd_enqueue_request(struct cryptd_queue *queue,
 	refcount_inc(refcnt);
 
 out_put_cpu:
-	put_cpu();
+	spin_unlock_bh(&cpu_queue->qlock);
 
 	return err;
 }
@@ -162,16 +166,11 @@ static void cryptd_queue_worker(struct work_struct *work)
 	cpu_queue = container_of(work, struct cryptd_cpu_queue, work);
 	/*
 	 * Only handle one request at a time to avoid hogging crypto workqueue.
-	 * preempt_disable/enable is used to prevent being preempted by
-	 * cryptd_enqueue_request(). local_bh_disable/enable is used to prevent
-	 * cryptd_enqueue_request() being accessed from software interrupts.
 	 */
-	local_bh_disable();
-	preempt_disable();
+	spin_lock_bh(&cpu_queue->qlock);
 	backlog = crypto_get_backlog(&cpu_queue->queue);
 	req = crypto_dequeue_request(&cpu_queue->queue);
-	preempt_enable();
-	local_bh_enable();
+	spin_unlock_bh(&cpu_queue->qlock);
 
 	if (!req)
 		return;
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index cb253d80d72b9..3d3f218b6ed6e 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -59,6 +59,40 @@ static void zram_free_page(struct zram *zram, size_t index);
 static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
 				u32 index, int offset, struct bio *bio);
 
+#ifdef CONFIG_PREEMPT_RT
+static void zram_meta_init_table_locks(struct zram *zram, size_t num_pages)
+{
+	size_t index;
+
+	for (index = 0; index < num_pages; index++)
+		spin_lock_init(&zram->table[index].lock);
+}
+
+static int zram_slot_trylock(struct zram *zram, u32 index)
+{
+	int ret;
+
+	ret = spin_trylock(&zram->table[index].lock);
+	if (ret)
+		__set_bit(ZRAM_LOCK, &zram->table[index].flags);
+	return ret;
+}
+
+static void zram_slot_lock(struct zram *zram, u32 index)
+{
+	spin_lock(&zram->table[index].lock);
+	__set_bit(ZRAM_LOCK, &zram->table[index].flags);
+}
+
+static void zram_slot_unlock(struct zram *zram, u32 index)
+{
+	__clear_bit(ZRAM_LOCK, &zram->table[index].flags);
+	spin_unlock(&zram->table[index].lock);
+}
+
+#else
+
+static void zram_meta_init_table_locks(struct zram *zram, size_t num_pages) { }
 
 static int zram_slot_trylock(struct zram *zram, u32 index)
 {
@@ -74,6 +108,7 @@ static void zram_slot_unlock(struct zram *zram, u32 index)
 {
 	bit_spin_unlock(ZRAM_LOCK, &zram->table[index].flags);
 }
+#endif
 
 static inline bool init_done(struct zram *zram)
 {
@@ -1199,6 +1234,7 @@ static bool zram_meta_alloc(struct zram *zram, u64 disksize)
 
 	if (!huge_class_size)
 		huge_class_size = zs_huge_class_size(zram->mem_pool);
+	zram_meta_init_table_locks(zram, num_pages);
 	return true;
 }
 
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index 80c3b43b4828f..d8f6d880f9151 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -63,6 +63,7 @@ struct zram_table_entry {
 		unsigned long element;
 	};
 	unsigned long flags;
+	spinlock_t lock;
 #ifdef CONFIG_ZRAM_MEMORY_TRACKING
 	ktime_t ac_time;
 #endif
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 68613f0b68877..79c0287920601 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -42,61 +42,6 @@
  */
 
 /*
- * (now, with legal B.S. out of the way.....)
- *
- * This routine gathers environmental noise from device drivers, etc.,
- * and returns good random numbers, suitable for cryptographic use.
- * Besides the obvious cryptographic uses, these numbers are also good
- * for seeding TCP sequence numbers, and other places where it is
- * desirable to have numbers which are not only random, but hard to
- * predict by an attacker.
- *
- * Theory of operation
- * ===================
- *
- * Computers are very predictable devices.  Hence it is extremely hard
- * to produce truly random numbers on a computer --- as opposed to
- * pseudo-random numbers, which can easily generated by using a
- * algorithm.  Unfortunately, it is very easy for attackers to guess
- * the sequence of pseudo-random number generators, and for some
- * applications this is not acceptable.  So instead, we must try to
- * gather "environmental noise" from the computer's environment, which
- * must be hard for outside attackers to observe, and use that to
- * generate random numbers.  In a Unix environment, this is best done
- * from inside the kernel.
- *
- * Sources of randomness from the environment include inter-keyboard
- * timings, inter-interrupt timings from some interrupts, and other
- * events which are both (a) non-deterministic and (b) hard for an
- * outside observer to measure.  Randomness from these sources are
- * added to an "entropy pool", which is mixed using a CRC-like function.
- * This is not cryptographically strong, but it is adequate assuming
- * the randomness is not chosen maliciously, and it is fast enough that
- * the overhead of doing it on every interrupt is very reasonable.
- * As random bytes are mixed into the entropy pool, the routines keep
- * an *estimate* of how many bits of randomness have been stored into
- * the random number generator's internal state.
- *
- * When random bytes are desired, they are obtained by taking the BLAKE2s
- * hash of the contents of the "entropy pool".  The BLAKE2s hash avoids
- * exposing the internal state of the entropy pool.  It is believed to
- * be computationally infeasible to derive any useful information
- * about the input of BLAKE2s from its output.  Even if it is possible to
- * analyze BLAKE2s in some clever way, as long as the amount of data
- * returned from the generator is less than the inherent entropy in
- * the pool, the output data is totally unpredictable.  For this
- * reason, the routine decreases its internal estimate of how many
- * bits of "true randomness" are contained in the entropy pool as it
- * outputs random numbers.
- *
- * If this estimate goes to zero, the routine can still generate
- * random numbers; however, an attacker may (at least in theory) be
- * able to infer the future output of the generator from prior
- * outputs.  This requires successful cryptanalysis of BLAKE2s, which is
- * not believed to be feasible, but there is a remote possibility.
- * Nonetheless, these numbers should be useful for the vast majority
- * of purposes.
- *
  * Exported interfaces ---- output
  * ===============================
  *
@@ -298,23 +243,6 @@
  *
  *	mknod /dev/random c 1 8
  *	mknod /dev/urandom c 1 9
- *
- * Acknowledgements:
- * =================
- *
- * Ideas for constructing this random number generator were derived
- * from Pretty Good Privacy's random number generator, and from private
- * discussions with Phil Karn.  Colin Plumb provided a faster random
- * number generator, which speed up the mixing function of the entropy
- * pool, taken from PGPfone.  Dale Worley has also contributed many
- * useful ideas and suggestions to improve this driver.
- *
- * Any flaws in the design are solely my responsibility, and should
- * not be attributed to the Phil, Colin, or any of authors of PGP.
- *
- * Further background information on this topic may be obtained from
- * RFC 1750, "Randomness Recommendations for Security", by Donald
- * Eastlake, Steve Crocker, and Jeff Schiller.
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -358,79 +286,15 @@
 
 /* #define ADD_INTERRUPT_BENCH */
 
-/*
- * If the entropy count falls under this number of bits, then we
- * should wake up processes which are selecting or polling on write
- * access to /dev/random.
- */
-static int random_write_wakeup_bits = 28 * (1 << 5);
-
-/*
- * Originally, we used a primitive polynomial of degree .poolwords
- * over GF(2).  The taps for various sizes are defined below.  They
- * were chosen to be evenly spaced except for the last tap, which is 1
- * to get the twisting happening as fast as possible.
- *
- * For the purposes of better mixing, we use the CRC-32 polynomial as
- * well to make a (modified) twisted Generalized Feedback Shift
- * Register.  (See M. Matsumoto & Y. Kurita, 1992.  Twisted GFSR
- * generators.  ACM Transactions on Modeling and Computer Simulation
- * 2(3):179-194.  Also see M. Matsumoto & Y. Kurita, 1994.  Twisted
- * GFSR generators II.  ACM Transactions on Modeling and Computer
- * Simulation 4:254-266)
- *
- * Thanks to Colin Plumb for suggesting this.
- *
- * The mixing operation is much less sensitive than the output hash,
- * where we use BLAKE2s.  All that we want of mixing operation is that
- * it be a good non-cryptographic hash; i.e. it not produce collisions
- * when fed "random" data of the sort we expect to see.  As long as
- * the pool state differs for different inputs, we have preserved the
- * input entropy and done a good job.  The fact that an intelligent
- * attacker can construct inputs that will produce controlled
- * alterations to the pool's state is not important because we don't
- * consider such inputs to contribute any randomness.  The only
- * property we need with respect to them is that the attacker can't
- * increase his/her knowledge of the pool's state.  Since all
- * additions are reversible (knowing the final state and the input,
- * you can reconstruct the initial state), if an attacker has any
- * uncertainty about the initial state, he/she can only shuffle that
- * uncertainty about, but never cause any collisions (which would
- * decrease the uncertainty).
- *
- * Our mixing functions were analyzed by Lacharme, Roeck, Strubel, and
- * Videau in their paper, "The Linux Pseudorandom Number Generator
- * Revisited" (see: http://eprint.iacr.org/2012/251.pdf).  In their
- * paper, they point out that we are not using a true Twisted GFSR,
- * since Matsumoto & Kurita used a trinomial feedback polynomial (that
- * is, with only three taps, instead of the six that we are using).
- * As a result, the resulting polynomial is neither primitive nor
- * irreducible, and hence does not have a maximal period over
- * GF(2**32).  They suggest a slight change to the generator
- * polynomial which improves the resulting TGFSR polynomial to be
- * irreducible, which we have made here.
- */
 enum poolinfo {
-	POOL_WORDS = 128,
-	POOL_WORDMASK = POOL_WORDS - 1,
-	POOL_BYTES = POOL_WORDS * sizeof(u32),
-	POOL_BITS = POOL_BYTES * 8,
+	POOL_BITS = BLAKE2S_HASH_SIZE * 8,
 	POOL_BITSHIFT = ilog2(POOL_BITS),
 
 	/* To allow fractional bits to be tracked, the entropy_count field is
 	 * denominated in units of 1/8th bits. */
 	POOL_ENTROPY_SHIFT = 3,
 #define POOL_ENTROPY_BITS() (input_pool.entropy_count >> POOL_ENTROPY_SHIFT)
-	POOL_FRACBITS = POOL_BITS << POOL_ENTROPY_SHIFT,
-
-	/* x^128 + x^104 + x^76 + x^51 +x^25 + x + 1 */
-	POOL_TAP1 = 104,
-	POOL_TAP2 = 76,
-	POOL_TAP3 = 51,
-	POOL_TAP4 = 25,
-	POOL_TAP5 = 1,
-
-	EXTRACT_SIZE = BLAKE2S_HASH_SIZE / 2
+	POOL_FRACBITS = POOL_BITS << POOL_ENTROPY_SHIFT
 };
 
 /*
@@ -438,6 +302,12 @@ enum poolinfo {
  */
 static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
 static struct fasync_struct *fasync;
+/*
+ * If the entropy count falls under this number of bits, then we
+ * should wake up processes which are selecting or polling on write
+ * access to /dev/random.
+ */
+static int random_write_wakeup_bits = POOL_BITS * 3 / 4;
 
 static DEFINE_SPINLOCK(random_ready_list_lock);
 static LIST_HEAD(random_ready_list);
@@ -493,79 +363,31 @@ MODULE_PARM_DESC(ratelimit_disable, "Disable random ratelimit suppression");
  *
  **********************************************************************/
 
-static u32 input_pool_data[POOL_WORDS] __latent_entropy;
-
 static struct {
+	struct blake2s_state hash;
 	spinlock_t lock;
-	u16 add_ptr;
-	u16 input_rotate;
 	int entropy_count;
 } input_pool = {
+	.hash.h = { BLAKE2S_IV0 ^ (0x01010000 | BLAKE2S_HASH_SIZE),
+		    BLAKE2S_IV1, BLAKE2S_IV2, BLAKE2S_IV3, BLAKE2S_IV4,
+		    BLAKE2S_IV5, BLAKE2S_IV6, BLAKE2S_IV7 },
+	.hash.outlen = BLAKE2S_HASH_SIZE,
 	.lock = __SPIN_LOCK_UNLOCKED(input_pool.lock),
 };
 
-static ssize_t extract_entropy(void *buf, size_t nbytes, int min);
-static ssize_t _extract_entropy(void *buf, size_t nbytes);
+static bool extract_entropy(void *buf, size_t nbytes, int min);
+static void _extract_entropy(void *buf, size_t nbytes);
 
 static void crng_reseed(struct crng_state *crng, bool use_input_pool);
 
-static const u32 twist_table[8] = {
-	0x00000000, 0x3b6e20c8, 0x76dc4190, 0x4db26158,
-	0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 };
-
 /*
  * This function adds bytes into the entropy "pool".  It does not
  * update the entropy estimate.  The caller should call
  * credit_entropy_bits if this is appropriate.
- *
- * The pool is stirred with a primitive polynomial of the appropriate
- * degree, and then twisted.  We twist by three bits at a time because
- * it's cheap to do so and helps slightly in the expected case where
- * the entropy is concentrated in the low-order bits.
  */
 static void _mix_pool_bytes(const void *in, int nbytes)
 {
-	unsigned long i;
-	int input_rotate;
-	const u8 *bytes = in;
-	u32 w;
-
-	input_rotate = input_pool.input_rotate;
-	i = input_pool.add_ptr;
-
-	/* mix one byte at a time to simplify size handling and churn faster */
-	while (nbytes--) {
-		w = rol32(*bytes++, input_rotate);
-		i = (i - 1) & POOL_WORDMASK;
-
-		/* XOR in the various taps */
-		w ^= input_pool_data[i];
-		w ^= input_pool_data[(i + POOL_TAP1) & POOL_WORDMASK];
-		w ^= input_pool_data[(i + POOL_TAP2) & POOL_WORDMASK];
-		w ^= input_pool_data[(i + POOL_TAP3) & POOL_WORDMASK];
-		w ^= input_pool_data[(i + POOL_TAP4) & POOL_WORDMASK];
-		w ^= input_pool_data[(i + POOL_TAP5) & POOL_WORDMASK];
-
-		/* Mix the result back in with a twist */
-		input_pool_data[i] = (w >> 3) ^ twist_table[w & 7];
-
-		/*
-		 * Normally, we add 7 bits of rotation to the pool.
-		 * At the beginning of the pool, add an extra 7 bits
-		 * rotation, so that successive passes spread the
-		 * input bits across the pool evenly.
-		 */
-		input_rotate = (input_rotate + (i ? 7 : 14)) & 31;
-	}
-
-	input_pool.input_rotate = input_rotate;
-	input_pool.add_ptr = i;
-}
-
-static void __mix_pool_bytes(const void *in, int nbytes)
-{
-	trace_mix_pool_bytes_nolock(nbytes, _RET_IP_);
-	_mix_pool_bytes(in, nbytes);
+	blake2s_update(&input_pool.hash, in, nbytes);
 }
 
 static void mix_pool_bytes(const void *in, int nbytes)
@@ -579,11 +401,13 @@ static void mix_pool_bytes(const void *in, int nbytes)
 }
 
 struct fast_pool {
-	u32 pool[4];
+	struct work_struct mix;
 	unsigned long last;
+	u32 pool[4];
+	atomic_t count;
 	u16 reg_idx;
-	u8 count;
 };
+#define FAST_POOL_MIX_INFLIGHT (1U << 31)
 
 /*
  * This is a fast mixing routine used by the interrupt randomness
@@ -613,7 +437,6 @@ static void fast_mix(struct fast_pool *f)
 
 	f->pool[0] = a;  f->pool[1] = b;
 	f->pool[2] = c;  f->pool[3] = d;
-	f->count++;
 }
 
 static void process_random_ready_list(void)
@@ -954,15 +777,14 @@ static int crng_slow_load(const u8 *cp, size_t len)
 static void crng_reseed(struct crng_state *crng, bool use_input_pool)
 {
 	unsigned long flags;
-	int i, num;
+	int i;
 	union {
 		u8 block[CHACHA_BLOCK_SIZE];
 		u32 key[8];
 	} buf;
 
 	if (use_input_pool) {
-		num = extract_entropy(&buf, 32, 16);
-		if (num == 0)
+		if (!extract_entropy(&buf, 32, 16))
 			return;
 	} else {
 		_extract_crng(&primary_crng, buf.block);
@@ -1220,12 +1042,37 @@ static u32 get_reg(struct fast_pool *f, struct pt_regs *regs)
 	return *ptr;
 }
 
+static void mix_interrupt_randomness(struct work_struct *work)
+{
+	struct fast_pool *fast_pool = container_of(work, struct fast_pool, mix);
+
+	fast_pool->last = jiffies;
+
+	/* Since this is the result of a trip through the scheduler, xor in
+	 * a cycle counter. It can't hurt, and might help.
+	 */
+	fast_pool->pool[3] ^= random_get_entropy();
+
+	if (unlikely(crng_init == 0)) {
+		if (crng_fast_load((u8 *)&fast_pool->pool, sizeof(fast_pool->pool)) > 0)
+			atomic_set(&fast_pool->count, 0);
+		else
+			atomic_and(~FAST_POOL_MIX_INFLIGHT, &fast_pool->count);
+		return;
+	}
+
+	mix_pool_bytes(&fast_pool->pool, sizeof(fast_pool->pool));
+	atomic_set(&fast_pool->count, 0);
+	credit_entropy_bits(1);
+}
+
 void add_interrupt_randomness(int irq)
 {
 	struct fast_pool *fast_pool = this_cpu_ptr(&irq_randomness);
 	struct pt_regs *regs = get_irq_regs();
 	unsigned long now = jiffies;
 	cycles_t cycles = random_get_entropy();
+	unsigned int new_count;
 	u32 c_high, j_high;
 	u64 ip;
 
@@ -1243,29 +1090,14 @@ void add_interrupt_randomness(int irq)
 	fast_mix(fast_pool);
 	add_interrupt_bench(cycles);
 
-	if (unlikely(crng_init == 0)) {
-		if ((fast_pool->count >= 64) &&
-		    crng_fast_load((u8 *)fast_pool->pool, sizeof(fast_pool->pool)) > 0) {
-			fast_pool->count = 0;
-			fast_pool->last = now;
-		}
-		return;
+	new_count = (unsigned int)atomic_inc_return(&fast_pool->count);
+	if (new_count >= 64 && new_count < FAST_POOL_MIX_INFLIGHT &&
+	    (time_after(now, fast_pool->last + HZ) || unlikely(crng_init == 0))) {
+		if (unlikely(!fast_pool->mix.func))
+			INIT_WORK(&fast_pool->mix, mix_interrupt_randomness);
+		atomic_or(FAST_POOL_MIX_INFLIGHT, &fast_pool->count);
+		schedule_work(&fast_pool->mix);
 	}
-
-	if ((fast_pool->count < 64) && !time_after(now, fast_pool->last + HZ))
-		return;
-
-	if (!spin_trylock(&input_pool.lock))
-		return;
-
-	fast_pool->last = now;
-	__mix_pool_bytes(&fast_pool->pool, sizeof(fast_pool->pool));
-	spin_unlock(&input_pool.lock);
-
-	fast_pool->count = 0;
-
-	/* award one bit for the contents of the fast pool */
-	credit_entropy_bits(1);
 }
 EXPORT_SYMBOL_GPL(add_interrupt_randomness);
 
@@ -1329,74 +1161,48 @@ static size_t account(size_t nbytes, int min)
 }
 
 /*
- * This function does the actual extraction for extract_entropy.
- *
- * Note: we assume that .poolwords is a multiple of 16 words.
+ * This is an HKDF-like construction for using the hashed collected entropy
+ * as a PRF key, that's then expanded block-by-block.
  */
-static void extract_buf(u8 *out)
+static void _extract_entropy(void *buf, size_t nbytes)
 {
-	struct blake2s_state state __aligned(__alignof__(unsigned long));
-	u8 hash[BLAKE2S_HASH_SIZE];
-	unsigned long *salt;
 	unsigned long flags;
+	u8 seed[BLAKE2S_HASH_SIZE], next_key[BLAKE2S_HASH_SIZE];
+	struct {
+		unsigned long rdrand[32 / sizeof(long)];
+		size_t counter;
+	} block;
+	size_t i;
 
-	blake2s_init(&state, sizeof(hash));
-
-	/*
-	 * If we have an architectural hardware random number
-	 * generator, use it for BLAKE2's salt & personal fields.
-	 */
-	for (salt = (unsigned long *)&state.h[4];
-	     salt < (unsigned long *)&state.h[8]; ++salt) {
-		unsigned long v;
-		if (!arch_get_random_long(&v))
-			break;
-		*salt ^= v;
+	for (i = 0; i < ARRAY_SIZE(block.rdrand); ++i) {
+		if (!arch_get_random_long(&block.rdrand[i]))
+			block.rdrand[i] = random_get_entropy();
 	}
 
-	/* Generate a hash across the pool */
 	spin_lock_irqsave(&input_pool.lock, flags);
-	blake2s_update(&state, (const u8 *)input_pool_data, POOL_BYTES);
-	blake2s_final(&state, hash); /* final zeros out state */
 
-	/*
-	 * We mix the hash back into the pool to prevent backtracking
-	 * attacks (where the attacker knows the state of the pool
-	 * plus the current outputs, and attempts to find previous
-	 * outputs), unless the hash function can be inverted. By
-	 * mixing at least a hash worth of hash data back, we make
-	 * brute-forcing the feedback as hard as brute-forcing the
-	 * hash.
-	 */
-	__mix_pool_bytes(hash, sizeof(hash));
+	/* seed = HASHPRF(last_key, entropy_input) */
+	blake2s_final(&input_pool.hash, seed);
+
+	/* next_key = HASHPRF(key, RDRAND || 0) */
+	block.counter = 0;
+	blake2s(next_key, (u8 *)&block, seed, sizeof(next_key), sizeof(block), sizeof(seed));
+	blake2s_init_key(&input_pool.hash, BLAKE2S_HASH_SIZE, next_key, sizeof(next_key));
+
 	spin_unlock_irqrestore(&input_pool.lock, flags);
-
-	/* Note that EXTRACT_SIZE is half of hash size here, because above
-	 * we've dumped the full length back into mixer. By reducing the
-	 * amount that we emit, we retain a level of forward secrecy.
-	 */
-	memcpy(out, hash, EXTRACT_SIZE);
-	memzero_explicit(hash, sizeof(hash));
-}
-
-static ssize_t _extract_entropy(void *buf, size_t nbytes)
-{
-	ssize_t ret = 0, i;
-	u8 tmp[EXTRACT_SIZE];
+	memzero_explicit(next_key, sizeof(next_key));
 
 	while (nbytes) {
-		extract_buf(tmp);
-		i = min_t(int, nbytes, EXTRACT_SIZE);
-		memcpy(buf, tmp, i);
+		i = min_t(size_t, nbytes, BLAKE2S_HASH_SIZE);
+		/* output = HASHPRF(key, RDRAND || ++counter) */
+		++block.counter;
+		blake2s(buf, (u8 *)&block, seed, i, sizeof(block), sizeof(seed));
 		nbytes -= i;
 		buf += i;
-		ret += i;
 	}
 
-	/* Wipe data just returned from memory */
-	memzero_explicit(tmp, sizeof(tmp));
-
-	return ret;
+	memzero_explicit(seed, sizeof(seed));
+	memzero_explicit(&block, sizeof(block));
 }
 
 /*
@@ -1404,13 +1210,18 @@ static ssize_t _extract_entropy(void *buf, size_t nbytes)
  * returns it in a buffer.
  *
  * The min parameter specifies the minimum amount we can pull before
- * failing to avoid races that defeat catastrophic reseeding.
+ * failing to avoid races that defeat catastrophic reseeding. If we
+ * have less than min entropy available, we return false and buf is
+ * not filled.
  */
-static ssize_t extract_entropy(void *buf, size_t nbytes, int min)
+static bool extract_entropy(void *buf, size_t nbytes, int min)
 {
 	trace_extract_entropy(nbytes, POOL_ENTROPY_BITS(), _RET_IP_);
-	nbytes = account(nbytes, min);
-	return _extract_entropy(buf, nbytes);
+	if (account(nbytes, min)) {
+		_extract_entropy(buf, nbytes);
+		return true;
+	}
+	return false;
 }
 
 #define warn_unseeded_randomness(previous) \
@@ -1674,7 +1485,7 @@ static void __init init_std_data(void)
 	unsigned long rv;
 
 	mix_pool_bytes(&now, sizeof(now));
-	for (i = POOL_BYTES; i > 0; i -= sizeof(rv)) {
+	for (i = BLAKE2S_BLOCK_SIZE; i > 0; i -= sizeof(rv)) {
 		if (!arch_get_random_seed_long(&rv) &&
 		    !arch_get_random_long(&rv))
 			rv = random_get_entropy();
diff --git a/drivers/char/tpm/tpm_tis.c b/drivers/char/tpm/tpm_tis.c
index d3f2e5364c275..9c4a99757afd3 100644
--- a/drivers/char/tpm/tpm_tis.c
+++ b/drivers/char/tpm/tpm_tis.c
@@ -50,6 +50,31 @@ static inline struct tpm_tis_tcg_phy *to_tpm_tis_tcg_phy(struct tpm_tis_data *da
 	return container_of(data, struct tpm_tis_tcg_phy, priv);
 }
 
+#ifdef CONFIG_PREEMPT_RT
+/*
+ * Flushes previous write operations to chip so that a subsequent
+ * ioread*()s won't stall a cpu.
+ */
+static inline void tpm_tis_flush(void __iomem *iobase)
+{
+	ioread8(iobase + TPM_ACCESS(0));
+}
+#else
+#define tpm_tis_flush(iobase) do { } while (0)
+#endif
+
+static inline void tpm_tis_iowrite8(u8 b, void __iomem *iobase, u32 addr)
+{
+	iowrite8(b, iobase + addr);
+	tpm_tis_flush(iobase);
+}
+
+static inline void tpm_tis_iowrite32(u32 b, void __iomem *iobase, u32 addr)
+{
+	iowrite32(b, iobase + addr);
+	tpm_tis_flush(iobase);
+}
+
 static int interrupts = -1;
 module_param(interrupts, int, 0444);
 MODULE_PARM_DESC(interrupts, "Enable interrupts");
@@ -169,7 +194,7 @@ static int tpm_tcg_write_bytes(struct tpm_tis_data *data, u32 addr, u16 len,
 	struct tpm_tis_tcg_phy *phy = to_tpm_tis_tcg_phy(data);
 
 	while (len--)
-		iowrite8(*value++, phy->iobase + addr);
+		tpm_tis_iowrite8(*value++, phy->iobase, addr);
 
 	return 0;
 }
@@ -196,7 +221,7 @@ static int tpm_tcg_write32(struct tpm_tis_data *data, u32 addr, u32 value)
 {
 	struct tpm_tis_tcg_phy *phy = to_tpm_tis_tcg_phy(data);
 
-	iowrite32(value, phy->iobase + addr);
+	tpm_tis_iowrite32(value, phy->iobase, addr);
 
 	return 0;
 }
diff --git a/drivers/gpu/drm/i915/display/intel_crtc.c b/drivers/gpu/drm/i915/display/intel_crtc.c
index 16c3ca66d9f0b..27f7c7fc86a26 100644
--- a/drivers/gpu/drm/i915/display/intel_crtc.c
+++ b/drivers/gpu/drm/i915/display/intel_crtc.c
@@ -517,7 +517,8 @@ void intel_pipe_update_start(struct intel_crtc_state *new_crtc_state)
 	 */
 	intel_psr_wait_for_idle(new_crtc_state);
 
-	local_irq_disable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_disable();
 
 	crtc->debug.min_vbl = min;
 	crtc->debug.max_vbl = max;
@@ -542,11 +543,13 @@ void intel_pipe_update_start(struct intel_crtc_state *new_crtc_state)
 			break;
 		}
 
-		local_irq_enable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_enable();
 
 		timeout = schedule_timeout(timeout);
 
-		local_irq_disable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_disable();
 	}
 
 	finish_wait(wq, &wait);
@@ -579,7 +582,8 @@ void intel_pipe_update_start(struct intel_crtc_state *new_crtc_state)
 	return;
 
 irq_disable:
-	local_irq_disable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_disable();
 }
 
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_VBLANK_EVADE)
@@ -678,7 +682,8 @@ void intel_pipe_update_end(struct intel_crtc_state *new_crtc_state)
 	 */
 	intel_vrr_send_push(new_crtc_state);
 
-	local_irq_enable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_enable();
 
 	if (intel_vgpu_active(dev_priv))
 		return;
diff --git a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c
index 209cf265bf746..6e1b9068d944c 100644
--- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c
+++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c
@@ -311,10 +311,9 @@ void __intel_breadcrumbs_park(struct intel_breadcrumbs *b)
 	/* Kick the work once more to drain the signalers, and disarm the irq */
 	irq_work_sync(&b->irq_work);
 	while (READ_ONCE(b->irq_armed) && !atomic_read(&b->active)) {
-		local_irq_disable();
-		signal_irq_work(&b->irq_work);
-		local_irq_enable();
+		irq_work_queue(&b->irq_work);
 		cond_resched();
+		irq_work_sync(&b->irq_work);
 	}
 }
 
diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
index a69df5e9e77af..2d5f0c226ad66 100644
--- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
+++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
@@ -1284,7 +1284,7 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
 	 * and context switches) submission.
 	 */
 
-	spin_lock(&sched_engine->lock);
+	spin_lock_irq(&sched_engine->lock);
 
 	/*
 	 * If the queue is higher priority than the last
@@ -1384,7 +1384,7 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
 				 * Even if ELSP[1] is occupied and not worthy
 				 * of timeslices, our queue might be.
 				 */
-				spin_unlock(&sched_engine->lock);
+				spin_unlock_irq(&sched_engine->lock);
 				return;
 			}
 		}
@@ -1410,7 +1410,7 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
 
 		if (last && !can_merge_rq(last, rq)) {
 			spin_unlock(&ve->base.sched_engine->lock);
-			spin_unlock(&engine->sched_engine->lock);
+			spin_unlock_irq(&engine->sched_engine->lock);
 			return; /* leave this for another sibling */
 		}
 
@@ -1572,7 +1572,7 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
 	 */
 	sched_engine->queue_priority_hint = queue_prio(sched_engine);
 	i915_sched_engine_reset_on_empty(sched_engine);
-	spin_unlock(&sched_engine->lock);
+	spin_unlock_irq(&sched_engine->lock);
 
 	/*
 	 * We can skip poking the HW if we ended up with exactly the same set
@@ -1598,13 +1598,6 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
 	}
 }
 
-static void execlists_dequeue_irq(struct intel_engine_cs *engine)
-{
-	local_irq_disable(); /* Suspend interrupts across request submission */
-	execlists_dequeue(engine);
-	local_irq_enable(); /* flush irq_work (e.g. breadcrumb enabling) */
-}
-
 static void clear_ports(struct i915_request **ports, int count)
 {
 	memset_p((void **)ports, NULL, count);
@@ -2425,7 +2418,7 @@ static void execlists_submission_tasklet(struct tasklet_struct *t)
 	}
 
 	if (!engine->execlists.pending[0]) {
-		execlists_dequeue_irq(engine);
+		execlists_dequeue(engine);
 		start_timeslice(engine);
 	}
 
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 21f75b069fa80..9beec0a8bbd53 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -916,7 +916,8 @@ static bool i915_get_crtc_scanoutpos(struct drm_crtc *_crtc,
 	 */
 	spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
 
-	/* preempt_disable_rt() should go right here in PREEMPT_RT patchset. */
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		preempt_disable();
 
 	/* Get optional system timestamp before query. */
 	if (stime)
@@ -980,7 +981,8 @@ static bool i915_get_crtc_scanoutpos(struct drm_crtc *_crtc,
 	if (etime)
 		*etime = ktime_get();
 
-	/* preempt_enable_rt() should go right here in PREEMPT_RT patchset. */
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		preempt_enable();
 
 	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
 
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 76cf5ac91e946..41d7c1071ab52 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -583,7 +583,6 @@ bool __i915_request_submit(struct i915_request *request)
 
 	RQ_TRACE(request, "\n");
 
-	GEM_BUG_ON(!irqs_disabled());
 	lockdep_assert_held(&engine->sched_engine->lock);
 
 	/*
@@ -692,7 +691,6 @@ void __i915_request_unsubmit(struct i915_request *request)
 	 */
 	RQ_TRACE(request, "\n");
 
-	GEM_BUG_ON(!irqs_disabled());
 	lockdep_assert_held(&engine->sched_engine->lock);
 
 	/*
diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h
index 37b5c9e9d260e..73f29d8008f0c 100644
--- a/drivers/gpu/drm/i915/i915_trace.h
+++ b/drivers/gpu/drm/i915/i915_trace.h
@@ -6,6 +6,10 @@
 #if !defined(_I915_TRACE_H_) || defined(TRACE_HEADER_MULTI_READ)
 #define _I915_TRACE_H_
 
+#ifdef CONFIG_PREEMPT_RT
+#define NOTRACE
+#endif
+
 #include <linux/stringify.h>
 #include <linux/types.h>
 #include <linux/tracepoint.h>
@@ -323,7 +327,7 @@ DEFINE_EVENT(i915_request, i915_request_add,
 	     TP_ARGS(rq)
 );
 
-#if defined(CONFIG_DRM_I915_LOW_LEVEL_TRACEPOINTS)
+#if defined(CONFIG_DRM_I915_LOW_LEVEL_TRACEPOINTS) && !defined(NOTRACE)
 DEFINE_EVENT(i915_request, i915_request_guc_submit,
 	     TP_PROTO(struct i915_request *rq),
 	     TP_ARGS(rq)
diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h
index 7a5925072466a..b7b56fb1e2fc7 100644
--- a/drivers/gpu/drm/i915/i915_utils.h
+++ b/drivers/gpu/drm/i915/i915_utils.h
@@ -344,7 +344,7 @@ wait_remaining_ms_from_jiffies(unsigned long timestamp_jiffies, int to_wait_ms)
 #define wait_for(COND, MS)		_wait_for((COND), (MS) * 1000, 10, 1000)
 
 /* If CONFIG_PREEMPT_COUNT is disabled, in_atomic() always reports false. */
-#if defined(CONFIG_DRM_I915_DEBUG) && defined(CONFIG_PREEMPT_COUNT)
+#if defined(CONFIG_DRM_I915_DEBUG) && defined(CONFIG_PREEMPT_COUNT) && !defined(CONFIG_PREEMPT_RT)
 # define _WAIT_FOR_ATOMIC_CHECK(ATOMIC) WARN_ON_ONCE((ATOMIC) && !in_atomic())
 #else
 # define _WAIT_FOR_ATOMIC_CHECK(ATOMIC) do { } while (0)
diff --git a/drivers/i2c/busses/i2c-cht-wc.c b/drivers/i2c/busses/i2c-cht-wc.c
index 1cf68f85b2e11..8ccf0c928bb44 100644
--- a/drivers/i2c/busses/i2c-cht-wc.c
+++ b/drivers/i2c/busses/i2c-cht-wc.c
@@ -99,15 +99,8 @@ static irqreturn_t cht_wc_i2c_adap_thread_handler(int id, void *data)
 	 * interrupt handler as well, so running the client irq handler from
 	 * this thread will cause things to lock up.
 	 */
-	if (reg & CHT_WC_EXTCHGRIRQ_CLIENT_IRQ) {
-		/*
-		 * generic_handle_irq expects local IRQs to be disabled
-		 * as normally it is called from interrupt context.
-		 */
-		local_irq_disable();
-		generic_handle_irq(adap->client_irq);
-		local_irq_enable();
-	}
+	if (reg & CHT_WC_EXTCHGRIRQ_CLIENT_IRQ)
+		generic_handle_irq_safe(adap->client_irq);
 
 	return IRQ_HANDLED;
 }
diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 2c59dd748a49f..3f9e5303b6163 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -1424,7 +1424,7 @@ int i2c_handle_smbus_host_notify(struct i2c_adapter *adap, unsigned short addr)
 	if (irq <= 0)
 		return -ENXIO;
 
-	generic_handle_irq(irq);
+	generic_handle_irq_safe(irq);
 
 	return 0;
 }
diff --git a/drivers/mfd/ezx-pcap.c b/drivers/mfd/ezx-pcap.c
index 70fa18b04ad2b..b14d3f98e1ebd 100644
--- a/drivers/mfd/ezx-pcap.c
+++ b/drivers/mfd/ezx-pcap.c
@@ -193,13 +193,11 @@ static void pcap_isr_work(struct work_struct *work)
 		ezx_pcap_write(pcap, PCAP_REG_MSR, isr | msr);
 		ezx_pcap_write(pcap, PCAP_REG_ISR, isr);
 
-		local_irq_disable();
 		service = isr & ~msr;
 		for (irq = pcap->irq_base; service; service >>= 1, irq++) {
 			if (service & 1)
-				generic_handle_irq(irq);
+				generic_handle_irq_safe(irq);
 		}
-		local_irq_enable();
 		ezx_pcap_write(pcap, PCAP_REG_MSR, pcap->msr);
 	} while (gpio_get_value(pdata->gpio));
 }
diff --git a/drivers/misc/hi6421v600-irq.c b/drivers/misc/hi6421v600-irq.c
index 1c763796cf1fa..caa3de37698b0 100644
--- a/drivers/misc/hi6421v600-irq.c
+++ b/drivers/misc/hi6421v600-irq.c
@@ -117,8 +117,8 @@ static irqreturn_t hi6421v600_irq_handler(int irq, void *__priv)
 			 * If both powerkey down and up IRQs are received,
 			 * handle them at the right order
 			 */
-			generic_handle_irq(priv->irqs[POWERKEY_DOWN]);
-			generic_handle_irq(priv->irqs[POWERKEY_UP]);
+			generic_handle_irq_safe(priv->irqs[POWERKEY_DOWN]);
+			generic_handle_irq_safe(priv->irqs[POWERKEY_UP]);
 			pending &= ~HISI_IRQ_POWERKEY_UP_DOWN;
 		}
 
@@ -126,7 +126,7 @@ static irqreturn_t hi6421v600_irq_handler(int irq, void *__priv)
 			continue;
 
 		for_each_set_bit(offset, &pending, BITS_PER_BYTE) {
-			generic_handle_irq(priv->irqs[offset + i * BITS_PER_BYTE]);
+			generic_handle_irq_safe(priv->irqs[offset + i * BITS_PER_BYTE]);
 		}
 	}
 
diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c
index ed0edf5884ef8..77f5b564382b6 100644
--- a/drivers/net/loopback.c
+++ b/drivers/net/loopback.c
@@ -86,7 +86,7 @@ static netdev_tx_t loopback_xmit(struct sk_buff *skb,
 	skb->protocol = eth_type_trans(skb, dev);
 
 	len = skb->len;
-	if (likely(netif_rx(skb) == NET_RX_SUCCESS))
+	if (likely(__netif_rx(skb) == NET_RX_SUCCESS))
 		dev_lstats_add(dev, len);
 
 	return NETDEV_TX_OK;
diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
index b8e20a3f2b84e..415f16662f88e 100644
--- a/drivers/net/usb/lan78xx.c
+++ b/drivers/net/usb/lan78xx.c
@@ -1537,11 +1537,8 @@ static void lan78xx_status(struct lan78xx_net *dev, struct urb *urb)
 		netif_dbg(dev, link, dev->net, "PHY INTR: 0x%08x\n", intdata);
 		lan78xx_defer_kevent(dev, EVENT_LINK_RESET);
 
-		if (dev->domain_data.phyirq > 0) {
-			local_irq_disable();
-			generic_handle_irq(dev->domain_data.phyirq);
-			local_irq_enable();
-		}
+		if (dev->domain_data.phyirq > 0)
+			generic_handle_irq_safe(dev->domain_data.phyirq);
 	} else {
 		netdev_warn(dev->net,
 			    "unexpected interrupt: 0x%08x\n", intdata);
diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c
index 6415f88738ada..556284ea978b0 100644
--- a/drivers/scsi/fcoe/fcoe.c
+++ b/drivers/scsi/fcoe/fcoe.c
@@ -1450,11 +1450,11 @@ static int fcoe_rcv(struct sk_buff *skb, struct net_device *netdev,
 static int fcoe_alloc_paged_crc_eof(struct sk_buff *skb, int tlen)
 {
 	struct fcoe_percpu_s *fps;
-	int rc;
+	int rc, cpu = get_cpu_light();
 
-	fps = &get_cpu_var(fcoe_percpu);
+	fps = &per_cpu(fcoe_percpu, cpu);
 	rc = fcoe_get_paged_crc_eof(skb, tlen, fps);
-	put_cpu_var(fcoe_percpu);
+	put_cpu_light();
 
 	return rc;
 }
@@ -1639,11 +1639,11 @@ static inline int fcoe_filter_frames(struct fc_lport *lport,
 		return 0;
 	}
 
-	stats = per_cpu_ptr(lport->stats, get_cpu());
+	stats = per_cpu_ptr(lport->stats, get_cpu_light());
 	stats->InvalidCRCCount++;
 	if (stats->InvalidCRCCount < 5)
 		printk(KERN_WARNING "fcoe: dropping frame with CRC error\n");
-	put_cpu();
+	put_cpu_light();
 	return -EINVAL;
 }
 
@@ -1684,7 +1684,7 @@ static void fcoe_recv_frame(struct sk_buff *skb)
 	 */
 	hp = (struct fcoe_hdr *) skb_network_header(skb);
 
-	stats = per_cpu_ptr(lport->stats, get_cpu());
+	stats = per_cpu_ptr(lport->stats, get_cpu_light());
 	if (unlikely(FC_FCOE_DECAPS_VER(hp) != FC_FCOE_VER)) {
 		if (stats->ErrorFrames < 5)
 			printk(KERN_WARNING "fcoe: FCoE version "
@@ -1716,13 +1716,13 @@ static void fcoe_recv_frame(struct sk_buff *skb)
 		goto drop;
 
 	if (!fcoe_filter_frames(lport, fp)) {
-		put_cpu();
+		put_cpu_light();
 		fc_exch_recv(lport, fp);
 		return;
 	}
 drop:
 	stats->ErrorFrames++;
-	put_cpu();
+	put_cpu_light();
 	kfree_skb(skb);
 }
 
diff --git a/drivers/scsi/fcoe/fcoe_ctlr.c b/drivers/scsi/fcoe/fcoe_ctlr.c
index 1756a0ac6f083..3a2cbf35ea3d6 100644
--- a/drivers/scsi/fcoe/fcoe_ctlr.c
+++ b/drivers/scsi/fcoe/fcoe_ctlr.c
@@ -828,7 +828,7 @@ static unsigned long fcoe_ctlr_age_fcfs(struct fcoe_ctlr *fip)
 
 	INIT_LIST_HEAD(&del_list);
 
-	stats = per_cpu_ptr(fip->lp->stats, get_cpu());
+	stats = per_cpu_ptr(fip->lp->stats, get_cpu_light());
 
 	list_for_each_entry_safe(fcf, next, &fip->fcfs, list) {
 		deadline = fcf->time + fcf->fka_period + fcf->fka_period / 2;
@@ -864,7 +864,7 @@ static unsigned long fcoe_ctlr_age_fcfs(struct fcoe_ctlr *fip)
 				sel_time = fcf->time;
 		}
 	}
-	put_cpu();
+	put_cpu_light();
 
 	list_for_each_entry_safe(fcf, next, &del_list, list) {
 		/* Removes fcf from current list */
diff --git a/drivers/scsi/libfc/fc_exch.c b/drivers/scsi/libfc/fc_exch.c
index 841000445b9a1..26d661ddc9509 100644
--- a/drivers/scsi/libfc/fc_exch.c
+++ b/drivers/scsi/libfc/fc_exch.c
@@ -825,10 +825,10 @@ static struct fc_exch *fc_exch_em_alloc(struct fc_lport *lport,
 	}
 	memset(ep, 0, sizeof(*ep));
 
-	cpu = get_cpu();
+	cpu = get_cpu_light();
 	pool = per_cpu_ptr(mp->pool, cpu);
 	spin_lock_bh(&pool->lock);
-	put_cpu();
+	put_cpu_light();
 
 	/* peek cache of free slot */
 	if (pool->left != FC_XID_UNKNOWN) {
diff --git a/drivers/staging/greybus/gpio.c b/drivers/staging/greybus/gpio.c
index 7e6347fe93f99..8a7cf1d0e9688 100644
--- a/drivers/staging/greybus/gpio.c
+++ b/drivers/staging/greybus/gpio.c
@@ -391,10 +391,7 @@ static int gb_gpio_request_handler(struct gb_operation *op)
 		return -EINVAL;
 	}
 
-	local_irq_disable();
-	ret = generic_handle_irq(irq);
-	local_irq_enable();
-
+	ret = generic_handle_irq_safe(irq);
 	if (ret)
 		dev_err(dev, "failed to invoke irq handler\n");
 
diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index db784ace25d83..827897a398e3b 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -132,12 +132,55 @@ static inline void serial_dl_write(struct uart_8250_port *up, int value)
 	up->dl_write(up, value);
 }
 
+static inline void serial8250_set_IER(struct uart_8250_port *up,
+				      unsigned char ier)
+{
+	struct uart_port *port = &up->port;
+	unsigned long flags;
+	bool is_console;
+
+	is_console = uart_console(port);
+
+	if (is_console)
+		printk_cpu_sync_get_irqsave(flags);
+
+	serial_out(up, UART_IER, ier);
+
+	if (is_console)
+		printk_cpu_sync_put_irqrestore(flags);
+}
+
+static inline unsigned char serial8250_clear_IER(struct uart_8250_port *up)
+{
+	struct uart_port *port = &up->port;
+	unsigned int clearval = 0;
+	unsigned long flags;
+	unsigned int prior;
+	bool is_console;
+
+	is_console = uart_console(port);
+
+	if (up->capabilities & UART_CAP_UUE)
+		clearval = UART_IER_UUE;
+
+	if (is_console)
+		printk_cpu_sync_get_irqsave(flags);
+
+	prior = serial_port_in(port, UART_IER);
+	serial_port_out(port, UART_IER, clearval);
+
+	if (is_console)
+		printk_cpu_sync_put_irqrestore(flags);
+
+	return prior;
+}
+
 static inline bool serial8250_set_THRI(struct uart_8250_port *up)
 {
 	if (up->ier & UART_IER_THRI)
 		return false;
 	up->ier |= UART_IER_THRI;
-	serial_out(up, UART_IER, up->ier);
+	serial8250_set_IER(up, up->ier);
 	return true;
 }
 
@@ -146,7 +189,7 @@ static inline bool serial8250_clear_THRI(struct uart_8250_port *up)
 	if (!(up->ier & UART_IER_THRI))
 		return false;
 	up->ier &= ~UART_IER_THRI;
-	serial_out(up, UART_IER, up->ier);
+	serial8250_set_IER(up, up->ier);
 	return true;
 }
 
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 01d30f6ed8fb5..da88bf4eda558 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -264,10 +264,8 @@ static void serial8250_backup_timeout(struct timer_list *t)
 	 * Must disable interrupts or else we risk racing with the interrupt
 	 * based handler.
 	 */
-	if (up->port.irq) {
-		ier = serial_in(up, UART_IER);
-		serial_out(up, UART_IER, 0);
-	}
+	if (up->port.irq)
+		ier = serial8250_clear_IER(up);
 
 	iir = serial_in(up, UART_IIR);
 
@@ -290,7 +288,7 @@ static void serial8250_backup_timeout(struct timer_list *t)
 		serial8250_tx_chars(up);
 
 	if (up->port.irq)
-		serial_out(up, UART_IER, ier);
+		serial8250_set_IER(up, ier);
 
 	spin_unlock_irqrestore(&up->port.lock, flags);
 
@@ -567,6 +565,14 @@ serial8250_register_ports(struct uart_driver *drv, struct device *dev)
 
 #ifdef CONFIG_SERIAL_8250_CONSOLE
 
+static void univ8250_console_write_atomic(struct console *co, const char *s,
+					  unsigned int count)
+{
+	struct uart_8250_port *up = &serial8250_ports[co->index];
+
+	serial8250_console_write_atomic(up, s, count);
+}
+
 static void univ8250_console_write(struct console *co, const char *s,
 				   unsigned int count)
 {
@@ -660,6 +666,7 @@ static int univ8250_console_match(struct console *co, char *name, int idx,
 
 static struct console univ8250_console = {
 	.name		= "ttyS",
+	.write_atomic	= univ8250_console_write_atomic,
 	.write		= univ8250_console_write,
 	.device		= uart_console_device,
 	.setup		= univ8250_console_setup,
diff --git a/drivers/tty/serial/8250/8250_fsl.c b/drivers/tty/serial/8250/8250_fsl.c
index 9c01c531349df..d9b651290e1c7 100644
--- a/drivers/tty/serial/8250/8250_fsl.c
+++ b/drivers/tty/serial/8250/8250_fsl.c
@@ -56,9 +56,18 @@ int fsl8250_handle_irq(struct uart_port *port)
 
 	/* Stop processing interrupts on input overrun */
 	if ((orig_lsr & UART_LSR_OE) && (up->overrun_backoff_time_ms > 0)) {
+		unsigned long flags;
 		unsigned long delay;
+		bool is_console;
 
+		is_console = uart_console(port);
+
+		if (is_console)
+			printk_cpu_sync_get_irqsave(flags);
 		up->ier = port->serial_in(port, UART_IER);
+		if (is_console)
+			printk_cpu_sync_put_irqrestore(flags);
+
 		if (up->ier & (UART_IER_RLSI | UART_IER_RDI)) {
 			port->ops->stop_rx(port);
 		} else {
diff --git a/drivers/tty/serial/8250/8250_ingenic.c b/drivers/tty/serial/8250/8250_ingenic.c
index 65402d05eff93..061d8e4072c65 100644
--- a/drivers/tty/serial/8250/8250_ingenic.c
+++ b/drivers/tty/serial/8250/8250_ingenic.c
@@ -146,6 +146,8 @@ OF_EARLYCON_DECLARE(x1000_uart, "ingenic,x1000-uart",
 
 static void ingenic_uart_serial_out(struct uart_port *p, int offset, int value)
 {
+	unsigned long flags;
+	bool is_console;
 	int ier;
 
 	switch (offset) {
@@ -167,7 +169,12 @@ static void ingenic_uart_serial_out(struct uart_port *p, int offset, int value)
 		 * If we have enabled modem status IRQs we should enable
 		 * modem mode.
 		 */
+		is_console = uart_console(p);
+		if (is_console)
+			printk_cpu_sync_get_irqsave(flags);
 		ier = p->serial_in(p, UART_IER);
+		if (is_console)
+			printk_cpu_sync_put_irqrestore(flags);
 
 		if (ier & UART_IER_MSI)
 			value |= UART_MCR_MDCE | UART_MCR_FCM;
diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
index fb65dc601b237..e5032e5abd8ea 100644
--- a/drivers/tty/serial/8250/8250_mtk.c
+++ b/drivers/tty/serial/8250/8250_mtk.c
@@ -218,12 +218,37 @@ static void mtk8250_shutdown(struct uart_port *port)
 
 static void mtk8250_disable_intrs(struct uart_8250_port *up, int mask)
 {
-	serial_out(up, UART_IER, serial_in(up, UART_IER) & (~mask));
+	struct uart_port *port = &up->port;
+	unsigned long flags;
+	unsigned int ier;
+	bool is_console;
+
+	is_console = uart_console(port);
+
+	if (is_console)
+		printk_cpu_sync_get_irqsave(flags);
+
+	ier = serial_in(up, UART_IER);
+	serial_out(up, UART_IER, ier & (~mask));
+
+	if (is_console)
+		printk_cpu_sync_put_irqrestore(flags);
 }
 
 static void mtk8250_enable_intrs(struct uart_8250_port *up, int mask)
 {
-	serial_out(up, UART_IER, serial_in(up, UART_IER) | mask);
+	struct uart_port *port = &up->port;
+	unsigned long flags;
+	unsigned int ier;
+
+	if (uart_console(port))
+		printk_cpu_sync_get_irqsave(flags);
+
+	ier = serial_in(up, UART_IER);
+	serial_out(up, UART_IER, ier | mask);
+
+	if (uart_console(port))
+		printk_cpu_sync_put_irqrestore(flags);
 }
 
 static void mtk8250_set_flow_ctrl(struct uart_8250_port *up, int mode)
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 3b12bfc1ed67b..25838a47c02b4 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -762,7 +762,7 @@ static void serial8250_set_sleep(struct uart_8250_port *p, int sleep)
 			serial_out(p, UART_EFR, UART_EFR_ECB);
 			serial_out(p, UART_LCR, 0);
 		}
-		serial_out(p, UART_IER, sleep ? UART_IERX_SLEEP : 0);
+		serial8250_set_IER(p, sleep ? UART_IERX_SLEEP : 0);
 		if (p->capabilities & UART_CAP_EFR) {
 			serial_out(p, UART_LCR, UART_LCR_CONF_MODE_B);
 			serial_out(p, UART_EFR, efr);
@@ -1436,7 +1436,7 @@ static void serial8250_stop_rx(struct uart_port *port)
 
 	up->ier &= ~(UART_IER_RLSI | UART_IER_RDI);
 	up->port.read_status_mask &= ~UART_LSR_DR;
-	serial_port_out(port, UART_IER, up->ier);
+	serial8250_set_IER(up, up->ier);
 
 	serial8250_rpm_put(up);
 }
@@ -1466,7 +1466,7 @@ void serial8250_em485_stop_tx(struct uart_8250_port *p)
 		serial8250_clear_and_reinit_fifos(p);
 
 		p->ier |= UART_IER_RLSI | UART_IER_RDI;
-		serial_port_out(&p->port, UART_IER, p->ier);
+		serial8250_set_IER(p, p->ier);
 	}
 }
 EXPORT_SYMBOL_GPL(serial8250_em485_stop_tx);
@@ -1688,7 +1688,7 @@ static void serial8250_disable_ms(struct uart_port *port)
 	mctrl_gpio_disable_ms(up->gpios);
 
 	up->ier &= ~UART_IER_MSI;
-	serial_port_out(port, UART_IER, up->ier);
+	serial8250_set_IER(up, up->ier);
 }
 
 static void serial8250_enable_ms(struct uart_port *port)
@@ -1704,7 +1704,7 @@ static void serial8250_enable_ms(struct uart_port *port)
 	up->ier |= UART_IER_MSI;
 
 	serial8250_rpm_get(up);
-	serial_port_out(port, UART_IER, up->ier);
+	serial8250_set_IER(up, up->ier);
 	serial8250_rpm_put(up);
 }
 
@@ -2125,14 +2125,7 @@ static void serial8250_put_poll_char(struct uart_port *port,
 	struct uart_8250_port *up = up_to_u8250p(port);
 
 	serial8250_rpm_get(up);
-	/*
-	 *	First save the IER then disable the interrupts
-	 */
-	ier = serial_port_in(port, UART_IER);
-	if (up->capabilities & UART_CAP_UUE)
-		serial_port_out(port, UART_IER, UART_IER_UUE);
-	else
-		serial_port_out(port, UART_IER, 0);
+	ier = serial8250_clear_IER(up);
 
 	wait_for_xmitr(up, BOTH_EMPTY);
 	/*
@@ -2145,7 +2138,7 @@ static void serial8250_put_poll_char(struct uart_port *port,
 	 *	and restore the IER
 	 */
 	wait_for_xmitr(up, BOTH_EMPTY);
-	serial_port_out(port, UART_IER, ier);
+	serial8250_set_IER(up, ier);
 	serial8250_rpm_put(up);
 }
 
@@ -2448,7 +2441,7 @@ void serial8250_do_shutdown(struct uart_port *port)
 	 */
 	spin_lock_irqsave(&port->lock, flags);
 	up->ier = 0;
-	serial_port_out(port, UART_IER, 0);
+	serial8250_set_IER(up, 0);
 	spin_unlock_irqrestore(&port->lock, flags);
 
 	synchronize_irq(port->irq);
@@ -2830,7 +2823,7 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
 	if (up->capabilities & UART_CAP_RTOIE)
 		up->ier |= UART_IER_RTOIE;
 
-	serial_port_out(port, UART_IER, up->ier);
+	serial8250_set_IER(up, up->ier);
 
 	if (up->capabilities & UART_CAP_EFR) {
 		unsigned char efr = 0;
@@ -3296,7 +3289,7 @@ EXPORT_SYMBOL_GPL(serial8250_set_defaults);
 
 #ifdef CONFIG_SERIAL_8250_CONSOLE
 
-static void serial8250_console_putchar(struct uart_port *port, int ch)
+static void serial8250_console_putchar_locked(struct uart_port *port, int ch)
 {
 	struct uart_8250_port *up = up_to_u8250p(port);
 
@@ -3304,6 +3297,18 @@ static void serial8250_console_putchar(struct uart_port *port, int ch)
 	serial_port_out(port, UART_TX, ch);
 }
 
+static void serial8250_console_putchar(struct uart_port *port, int ch)
+{
+	struct uart_8250_port *up = up_to_u8250p(port);
+	unsigned long flags;
+
+	wait_for_xmitr(up, UART_LSR_THRE);
+
+	printk_cpu_sync_get_irqsave(flags);
+	serial8250_console_putchar_locked(port, ch);
+	printk_cpu_sync_put_irqrestore(flags);
+}
+
 /*
  *	Restore serial console when h/w power-off detected
  */
@@ -3325,6 +3330,32 @@ static void serial8250_console_restore(struct uart_8250_port *up)
 	serial8250_out_MCR(up, UART_MCR_DTR | UART_MCR_RTS);
 }
 
+void serial8250_console_write_atomic(struct uart_8250_port *up,
+				     const char *s, unsigned int count)
+{
+	struct uart_port *port = &up->port;
+	unsigned long flags;
+	unsigned int ier;
+
+	printk_cpu_sync_get_irqsave(flags);
+
+	touch_nmi_watchdog();
+
+	ier = serial8250_clear_IER(up);
+
+	if (atomic_fetch_inc(&up->console_printing)) {
+		uart_console_write(port, "\n", 1,
+				   serial8250_console_putchar_locked);
+	}
+	uart_console_write(port, s, count, serial8250_console_putchar_locked);
+	atomic_dec(&up->console_printing);
+
+	wait_for_xmitr(up, BOTH_EMPTY);
+	serial8250_set_IER(up, ier);
+
+	printk_cpu_sync_put_irqrestore(flags);
+}
+
 /*
  *	Print a string to the serial port trying not to disturb
  *	any possible real use of the port...
@@ -3341,24 +3372,12 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s,
 	struct uart_port *port = &up->port;
 	unsigned long flags;
 	unsigned int ier;
-	int locked = 1;
 
 	touch_nmi_watchdog();
 
-	if (oops_in_progress)
-		locked = spin_trylock_irqsave(&port->lock, flags);
-	else
-		spin_lock_irqsave(&port->lock, flags);
+	spin_lock_irqsave(&port->lock, flags);
 
-	/*
-	 *	First save the IER then disable the interrupts
-	 */
-	ier = serial_port_in(port, UART_IER);
-
-	if (up->capabilities & UART_CAP_UUE)
-		serial_port_out(port, UART_IER, UART_IER_UUE);
-	else
-		serial_port_out(port, UART_IER, 0);
+	ier = serial8250_clear_IER(up);
 
 	/* check scratch reg to see if port powered off during system sleep */
 	if (up->canary && (up->canary != serial_port_in(port, UART_SCR))) {
@@ -3372,7 +3391,9 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s,
 		mdelay(port->rs485.delay_rts_before_send);
 	}
 
+	atomic_inc(&up->console_printing);
 	uart_console_write(port, s, count, serial8250_console_putchar);
+	atomic_dec(&up->console_printing);
 
 	/*
 	 *	Finally, wait for transmitter to become empty
@@ -3385,8 +3406,7 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s,
 		if (em485->tx_stopped)
 			up->rs485_stop_tx(up);
 	}
-
-	serial_port_out(port, UART_IER, ier);
+	serial8250_set_IER(up, ier);
 
 	/*
 	 *	The receive handling will happen properly because the
@@ -3398,8 +3418,7 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s,
 	if (up->msr_saved_flags)
 		serial8250_modem_status(up);
 
-	if (locked)
-		spin_unlock_irqrestore(&port->lock, flags);
+	spin_unlock_irqrestore(&port->lock, flags);
 }
 
 static unsigned int probe_baud(struct uart_port *port)
@@ -3419,6 +3438,7 @@ static unsigned int probe_baud(struct uart_port *port)
 
 int serial8250_console_setup(struct uart_port *port, char *options, bool probe)
 {
+	struct uart_8250_port *up = up_to_u8250p(port);
 	int baud = 9600;
 	int bits = 8;
 	int parity = 'n';
@@ -3428,6 +3448,8 @@ int serial8250_console_setup(struct uart_port *port, char *options, bool probe)
 	if (!port->iobase && !port->membase)
 		return -ENODEV;
 
+	atomic_set(&up->console_printing, 0);
+
 	if (options)
 		uart_parse_options(options, &baud, &parity, &bits, &flow);
 	else if (probe)
diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
index 9d415a38cc71e..71c026d7d1b5b 100644
--- a/drivers/tty/serial/8250/Kconfig
+++ b/drivers/tty/serial/8250/Kconfig
@@ -9,6 +9,7 @@ config SERIAL_8250
 	depends on !S390
 	select SERIAL_CORE
 	select SERIAL_MCTRL_GPIO if GPIOLIB
+	select HAVE_ATOMIC_CONSOLE
 	help
 	  This selects whether you want to include the driver for the standard
 	  serial ports.  The standard answer is Y.  People who might say N
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index ba053a68529f7..52213a2c33eae 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -2270,18 +2270,24 @@ pl011_console_write(struct console *co, const char *s, unsigned int count)
 {
 	struct uart_amba_port *uap = amba_ports[co->index];
 	unsigned int old_cr = 0, new_cr;
-	unsigned long flags;
+	unsigned long flags = 0;
 	int locked = 1;
 
 	clk_enable(uap->clk);
 
-	local_irq_save(flags);
+	/*
+	 * local_irq_save(flags);
+	 *
+	 * This local_irq_save() is nonsense. If we come in via sysrq
+	 * handling then interrupts are already disabled. Aside of
+	 * that the port.sysrq check is racy on SMP regardless.
+	*/
 	if (uap->port.sysrq)
 		locked = 0;
 	else if (oops_in_progress)
-		locked = spin_trylock(&uap->port.lock);
+		locked = spin_trylock_irqsave(&uap->port.lock, flags);
 	else
-		spin_lock(&uap->port.lock);
+		spin_lock_irqsave(&uap->port.lock, flags);
 
 	/*
 	 *	First save the CR then disable the interrupts
@@ -2307,8 +2313,7 @@ pl011_console_write(struct console *co, const char *s, unsigned int count)
 		pl011_write(old_cr, uap, REG_CR);
 
 	if (locked)
-		spin_unlock(&uap->port.lock);
-	local_irq_restore(flags);
+		spin_unlock_irqrestore(&uap->port.lock, flags);
 
 	clk_disable(uap->clk);
 }
diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index 0862941862c8b..10970632f0e47 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -1255,13 +1255,10 @@ serial_omap_console_write(struct console *co, const char *s,
 	unsigned int ier;
 	int locked = 1;
 
-	local_irq_save(flags);
-	if (up->port.sysrq)
-		locked = 0;
-	else if (oops_in_progress)
-		locked = spin_trylock(&up->port.lock);
+	if (up->port.sysrq || oops_in_progress)
+		locked = spin_trylock_irqsave(&up->port.lock, flags);
 	else
-		spin_lock(&up->port.lock);
+		spin_lock_irqsave(&up->port.lock, flags);
 
 	/*
 	 * First save the IER then disable the interrupts
@@ -1288,8 +1285,7 @@ serial_omap_console_write(struct console *co, const char *s,
 		check_modem_status(up);
 
 	if (locked)
-		spin_unlock(&up->port.lock);
-	local_irq_restore(flags);
+		spin_unlock_irqrestore(&up->port.lock, flags);
 }
 
 static int __init
diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
index bbfd004449b5b..a809f56c392f0 100644
--- a/drivers/tty/sysrq.c
+++ b/drivers/tty/sysrq.c
@@ -594,9 +594,11 @@ void __handle_sysrq(int key, bool check_mask)
 		 * should not) and is the invoked operation enabled?
 		 */
 		if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
+			printk_direct_enter();
 			pr_info("%s\n", op_p->action_msg);
 			console_loglevel = orig_log_level;
 			op_p->handler(key);
+			printk_direct_exit();
 		} else {
 			pr_info("This sysrq operation is disabled.\n");
 			console_loglevel = orig_log_level;
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index f8c87c4d73995..15f071c09aa72 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -3161,7 +3161,7 @@ static struct console vt_console_driver = {
 	.write		= vt_console_print,
 	.device		= vt_console_device,
 	.unblank	= unblank_screen,
-	.flags		= CON_PRINTBUFFER,
+	.flags		= CON_PRINTBUFFER|CON_MIGHT_SLEEP,
 	.index		= -1,
 };
 #endif
diff --git a/drivers/virt/acrn/irqfd.c b/drivers/virt/acrn/irqfd.c
index df5184979b282..d4ad211dce7a3 100644
--- a/drivers/virt/acrn/irqfd.c
+++ b/drivers/virt/acrn/irqfd.c
@@ -17,7 +17,6 @@
 #include "acrn_drv.h"
 
 static LIST_HEAD(acrn_irqfd_clients);
-static DEFINE_MUTEX(acrn_irqfds_mutex);
 
 /**
  * struct hsm_irqfd - Properties of HSM irqfd
diff --git a/fs/afs/dir_silly.c b/fs/afs/dir_silly.c
index 45cfd50a95210..502b56597f107 100644
--- a/fs/afs/dir_silly.c
+++ b/fs/afs/dir_silly.c
@@ -239,7 +239,7 @@ int afs_silly_iput(struct dentry *dentry, struct inode *inode)
 	struct dentry *alias;
 	int ret;
 
-	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
+	DECLARE_SWAIT_QUEUE_HEAD_ONSTACK(wq);
 
 	_enter("%p{%pd},%llx", dentry, dentry, vnode->fid.vnode);
 
diff --git a/fs/cifs/readdir.c b/fs/cifs/readdir.c
index 1929e80c09ee1..48eb8c30c6dbf 100644
--- a/fs/cifs/readdir.c
+++ b/fs/cifs/readdir.c
@@ -69,7 +69,7 @@ cifs_prime_dcache(struct dentry *parent, struct qstr *name,
 	struct inode *inode;
 	struct super_block *sb = parent->d_sb;
 	struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
-	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
+	DECLARE_SWAIT_QUEUE_HEAD_ONSTACK(wq);
 
 	cifs_dbg(FYI, "%s: for %s\n", __func__, name->name);
 
diff --git a/fs/dcache.c b/fs/dcache.c
index c84269c6e8bf6..f6cc7473bc6e1 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2562,7 +2562,13 @@ EXPORT_SYMBOL(d_rehash);
 
 static inline unsigned start_dir_add(struct inode *dir)
 {
-
+	/*
+	 * The caller has a spinlock_t (dentry::d_lock) acquired which disables
+	 * preemption on !PREEMPT_RT. On PREEMPT_RT the lock does not disable
+	 * preemption and it has be done explicitly.
+	 */
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		preempt_disable();
 	for (;;) {
 		unsigned n = dir->i_dir_seq;
 		if (!(n & 1) && cmpxchg(&dir->i_dir_seq, n, n + 1) == n)
@@ -2574,25 +2580,30 @@ static inline unsigned start_dir_add(struct inode *dir)
 static inline void end_dir_add(struct inode *dir, unsigned n)
 {
 	smp_store_release(&dir->i_dir_seq, n + 2);
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		preempt_enable();
 }
 
 static void d_wait_lookup(struct dentry *dentry)
 {
-	if (d_in_lookup(dentry)) {
-		DECLARE_WAITQUEUE(wait, current);
-		add_wait_queue(dentry->d_wait, &wait);
-		do {
-			set_current_state(TASK_UNINTERRUPTIBLE);
-			spin_unlock(&dentry->d_lock);
-			schedule();
-			spin_lock(&dentry->d_lock);
-		} while (d_in_lookup(dentry));
-	}
+	struct swait_queue __wait;
+
+	if (!d_in_lookup(dentry))
+		return;
+
+	INIT_LIST_HEAD(&__wait.task_list);
+	do {
+		prepare_to_swait_exclusive(dentry->d_wait, &__wait, TASK_UNINTERRUPTIBLE);
+		spin_unlock(&dentry->d_lock);
+		schedule();
+		spin_lock(&dentry->d_lock);
+	} while (d_in_lookup(dentry));
+	finish_swait(dentry->d_wait, &__wait);
 }
 
 struct dentry *d_alloc_parallel(struct dentry *parent,
 				const struct qstr *name,
-				wait_queue_head_t *wq)
+				struct swait_queue_head *wq)
 {
 	unsigned int hash = name->hash;
 	struct hlist_bl_head *b = in_lookup_hash(parent, hash);
@@ -2707,7 +2718,7 @@ void __d_lookup_done(struct dentry *dentry)
 	hlist_bl_lock(b);
 	dentry->d_flags &= ~DCACHE_PAR_LOOKUP;
 	__hlist_bl_del(&dentry->d_u.d_in_lookup_hash);
-	wake_up_all(dentry->d_wait);
+	swake_up_all(dentry->d_wait);
 	dentry->d_wait = NULL;
 	hlist_bl_unlock(b);
 	INIT_HLIST_NODE(&dentry->d_u.d_alias);
diff --git a/fs/fuse/readdir.c b/fs/fuse/readdir.c
index b4e5657110457..5ef0c106fb9db 100644
--- a/fs/fuse/readdir.c
+++ b/fs/fuse/readdir.c
@@ -158,7 +158,7 @@ static int fuse_direntplus_link(struct file *file,
 	struct inode *dir = d_inode(parent);
 	struct fuse_conn *fc;
 	struct inode *inode;
-	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
+	DECLARE_SWAIT_QUEUE_HEAD_ONSTACK(wq);
 
 	if (!o->nodeid) {
 		/*
diff --git a/fs/namei.c b/fs/namei.c
index 3f1829b3ab5b7..456d44d8c0ab2 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1683,7 +1683,7 @@ static struct dentry *__lookup_slow(const struct qstr *name,
 {
 	struct dentry *dentry, *old;
 	struct inode *inode = dir->d_inode;
-	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
+	DECLARE_SWAIT_QUEUE_HEAD_ONSTACK(wq);
 
 	/* Don't go there if it's already dead */
 	if (unlikely(IS_DEADDIR(inode)))
@@ -3242,7 +3242,7 @@ static struct dentry *lookup_open(struct nameidata *nd, struct file *file,
 	struct dentry *dentry;
 	int error, create_error = 0;
 	umode_t mode = op->mode;
-	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
+	DECLARE_SWAIT_QUEUE_HEAD_ONSTACK(wq);
 
 	if (unlikely(IS_DEADDIR(dir_inode)))
 		return ERR_PTR(-ENOENT);
diff --git a/fs/namespace.c b/fs/namespace.c
index 40b994a29e90d..c6feb92209a6f 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -344,8 +344,24 @@ int __mnt_want_write(struct vfsmount *m)
 	 * incremented count after it has set MNT_WRITE_HOLD.
 	 */
 	smp_mb();
-	while (READ_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD)
-		cpu_relax();
+	might_lock(&mount_lock.lock);
+	while (READ_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD) {
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT)) {
+			cpu_relax();
+		} else {
+			/*
+			 * This prevents priority inversion, if the task
+			 * setting MNT_WRITE_HOLD got preempted on a remote
+			 * CPU, and it prevents life lock if the task setting
+			 * MNT_WRITE_HOLD has a lower priority and is bound to
+			 * the same CPU as the task that is spinning here.
+			 */
+			preempt_enable();
+			lock_mount_hash();
+			unlock_mount_hash();
+			preempt_disable();
+		}
+	}
 	/*
 	 * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will
 	 * be set to match its requirements. So we must not load that until
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 848f3b8fb8219..f4955895e9665 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -639,7 +639,7 @@ void nfs_prime_dcache(struct dentry *parent, struct nfs_entry *entry,
 		unsigned long dir_verifier)
 {
 	struct qstr filename = QSTR_INIT(entry->name, entry->len);
-	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
+	DECLARE_SWAIT_QUEUE_HEAD_ONSTACK(wq);
 	struct dentry *dentry;
 	struct dentry *alias;
 	struct inode *inode;
@@ -1883,7 +1883,7 @@ int nfs_atomic_open(struct inode *dir, struct dentry *dentry,
 		    struct file *file, unsigned open_flags,
 		    umode_t mode)
 {
-	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
+	DECLARE_SWAIT_QUEUE_HEAD_ONSTACK(wq);
 	struct nfs_open_context *ctx;
 	struct dentry *res;
 	struct iattr attr = { .ia_valid = ATTR_OPEN };
diff --git a/fs/nfs/unlink.c b/fs/nfs/unlink.c
index 5fa11e1aca4c2..984f26eb888c1 100644
--- a/fs/nfs/unlink.c
+++ b/fs/nfs/unlink.c
@@ -13,7 +13,7 @@
 #include <linux/sunrpc/clnt.h>
 #include <linux/nfs_fs.h>
 #include <linux/sched.h>
-#include <linux/wait.h>
+#include <linux/swait.h>
 #include <linux/namei.h>
 #include <linux/fsnotify.h>
 
@@ -180,7 +180,7 @@ nfs_async_unlink(struct dentry *dentry, const struct qstr *name)
 
 	data->cred = get_current_cred();
 	data->res.dir_attr = &data->dir_attr;
-	init_waitqueue_head(&data->wq);
+	init_swait_queue_head(&data->wq);
 
 	status = -EBUSY;
 	spin_lock(&dentry->d_lock);
diff --git a/fs/proc/base.c b/fs/proc/base.c
index d654ce7150fdd..193d679e370de 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -96,6 +96,7 @@
 #include <linux/posix-timers.h>
 #include <linux/time_namespace.h>
 #include <linux/resctrl.h>
+#include <linux/swait.h>
 #include <linux/cn_proc.h>
 #include <trace/events/oom.h>
 #include "internal.h"
@@ -2045,7 +2046,7 @@ bool proc_fill_cache(struct file *file, struct dir_context *ctx,
 
 	child = d_hash_and_lookup(dir, &qname);
 	if (!child) {
-		DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
+		DECLARE_SWAIT_QUEUE_HEAD_ONSTACK(wq);
 		child = d_alloc_parallel(dir, &qname, &wq);
 		if (IS_ERR(child))
 			goto end_instantiate;
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 7d9cfc730bd4c..a4ddc8df10854 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -696,7 +696,7 @@ static bool proc_sys_fill_cache(struct file *file,
 
 	child = d_lookup(dir, &qname);
 	if (!child) {
-		DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
+		DECLARE_SWAIT_QUEUE_HEAD_ONSTACK(wq);
 		child = d_alloc_parallel(dir, &qname, &wq);
 		if (IS_ERR(child))
 			return false;
diff --git a/include/asm-generic/softirq_stack.h b/include/asm-generic/softirq_stack.h
index eceeecf6a5bd8..d3e2d81656e04 100644
--- a/include/asm-generic/softirq_stack.h
+++ b/include/asm-generic/softirq_stack.h
@@ -2,7 +2,7 @@
 #ifndef __ASM_GENERIC_SOFTIRQ_STACK_H
 #define __ASM_GENERIC_SOFTIRQ_STACK_H
 
-#ifdef CONFIG_HAVE_SOFTIRQ_ON_OWN_STACK
+#if defined(CONFIG_HAVE_SOFTIRQ_ON_OWN_STACK) && !defined(CONFIG_PREEMPT_RT)
 void do_softirq_own_stack(void);
 #else
 static inline void do_softirq_own_stack(void)
diff --git a/include/linux/console.h b/include/linux/console.h
index 7cd758a4f44ed..8986ad4478f20 100644
--- a/include/linux/console.h
+++ b/include/linux/console.h
@@ -16,6 +16,7 @@
 
 #include <linux/atomic.h>
 #include <linux/types.h>
+#include <linux/mutex.h>
 
 struct vc_data;
 struct console_font_op;
@@ -133,13 +134,25 @@ static inline int con_debug_leave(void)
 #define CON_CONSDEV	(2) /* Preferred console, /dev/console */
 #define CON_ENABLED	(4)
 #define CON_BOOT	(8)
-#define CON_ANYTIME	(16) /* Safe to call when cpu is offline */
+#define CON_ANYTIME	(16) /* Safe to call before per-cpu resources ready */
 #define CON_BRL		(32) /* Used for a braille device */
 #define CON_EXTENDED	(64) /* Use the extended output format a la /dev/kmsg */
+#define CON_PAUSED	(128) /* Sleep while console is locked */
+#define CON_MIGHT_SLEEP	(256) /* Can only be called from sleepable context */
+
+#ifdef CONFIG_HAVE_ATOMIC_CONSOLE
+struct console_atomic_data {
+	u64	seq;
+	char	*text;
+	char	*ext_text;
+	char	*dropped_text;
+};
+#endif
 
 struct console {
 	char	name[16];
 	void	(*write)(struct console *, const char *, unsigned);
+	void	(*write_atomic)(struct console *, const char *, unsigned);
 	int	(*read)(struct console *, char *, unsigned);
 	struct tty_driver *(*device)(struct console *, int *);
 	void	(*unblank)(void);
@@ -151,6 +164,26 @@ struct console {
 	int	cflag;
 	uint	ispeed;
 	uint	ospeed;
+	u64	seq;
+	atomic_long_t dropped;
+#ifdef CONFIG_HAVE_ATOMIC_CONSOLE
+	struct console_atomic_data *atomic_data;
+#endif
+	struct task_struct *thread;
+
+	/*
+	 * The per-console lock is used by printing kthreads to synchronize
+	 * this console with callers of console_lock(). This is necessary in
+	 * order to allow printing kthreads to run in parallel to each other,
+	 * while each safely accessing their own @flags and synchronizing
+	 * against direct printing via console_lock/console_unlock.
+	 *
+	 * Note: For synchronizing against direct printing via
+	 *       console_trylock/console_unlock, see the static global
+	 *       variable @console_lock_count.
+	 */
+	struct mutex lock;
+
 	void	*data;
 	struct	 console *next;
 };
@@ -165,6 +198,7 @@ extern int console_set_on_cmdline;
 extern struct console *early_console;
 
 enum con_flush_mode {
+	CONSOLE_ATOMIC_FLUSH_PENDING,
 	CONSOLE_FLUSH_PENDING,
 	CONSOLE_REPLAY_ALL,
 };
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index f5bba51480b2f..7c43c64343bb1 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -98,7 +98,7 @@ struct dentry {
 
 	union {
 		struct list_head d_lru;		/* LRU list */
-		wait_queue_head_t *d_wait;	/* in-lookup ones only */
+		struct swait_queue_head *d_wait;	/* in-lookup ones only */
 	};
 	struct list_head d_child;	/* child of parent list */
 	struct list_head d_subdirs;	/* our children */
@@ -230,7 +230,7 @@ extern void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op
 extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
 extern struct dentry * d_alloc_anon(struct super_block *);
 extern struct dentry * d_alloc_parallel(struct dentry *, const struct qstr *,
-					wait_queue_head_t *);
+					struct swait_queue_head *);
 extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
 extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *);
 extern struct dentry * d_exact_alias(struct dentry *, struct inode *);
diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index 2e2b8d6140ed4..71064a2c2cafe 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -57,9 +57,15 @@
 # define ARCH_EXIT_TO_USER_MODE_WORK		(0)
 #endif
 
+#ifdef CONFIG_PREEMPT_LAZY
+# define _TIF_NEED_RESCHED_MASK	(_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY)
+#else
+# define _TIF_NEED_RESCHED_MASK	(_TIF_NEED_RESCHED)
+#endif
+
 #define EXIT_TO_USER_MODE_WORK						\
 	(_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_UPROBE |		\
-	 _TIF_NEED_RESCHED | _TIF_PATCH_PENDING | _TIF_NOTIFY_SIGNAL |	\
+	 _TIF_NEED_RESCHED_MASK | _TIF_PATCH_PENDING | _TIF_NOTIFY_SIGNAL |	\
 	 ARCH_EXIT_TO_USER_MODE_WORK)
 
 /**
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 9367f1cb2e3c4..db4a23d07a571 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -605,6 +605,22 @@ extern void __raise_softirq_irqoff(unsigned int nr);
 extern void raise_softirq_irqoff(unsigned int nr);
 extern void raise_softirq(unsigned int nr);
 
+#ifdef CONFIG_PREEMPT_RT
+extern void raise_timer_softirq(void);
+extern void raise_hrtimer_softirq(void);
+
+#else
+static inline void raise_timer_softirq(void)
+{
+	raise_softirq(TIMER_SOFTIRQ);
+}
+
+static inline void raise_hrtimer_softirq(void)
+{
+	raise_softirq_irqoff(HRTIMER_SOFTIRQ);
+}
+#endif
+
 DECLARE_PER_CPU(struct task_struct *, ksoftirqd);
 
 static inline struct task_struct *this_cpu_ksoftirqd(void)
diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index 93d270ca0c567..a77584593f7d1 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -160,6 +160,7 @@ static inline void generic_handle_irq_desc(struct irq_desc *desc)
 
 int handle_irq_desc(struct irq_desc *desc);
 int generic_handle_irq(unsigned int irq);
+int generic_handle_irq_safe(unsigned int irq);
 
 #ifdef CONFIG_IRQ_DOMAIN
 /*
diff --git a/include/linux/local_lock_internal.h b/include/linux/local_lock_internal.h
index 975e33b793a77..6d635e8306d64 100644
--- a/include/linux/local_lock_internal.h
+++ b/include/linux/local_lock_internal.h
@@ -44,9 +44,9 @@ static inline void local_lock_debug_init(local_lock_t *l)
 }
 #else /* CONFIG_DEBUG_LOCK_ALLOC */
 # define LOCAL_LOCK_DEBUG_INIT(lockname)
-static inline void local_lock_acquire(local_lock_t *l) { }
-static inline void local_lock_release(local_lock_t *l) { }
-static inline void local_lock_debug_init(local_lock_t *l) { }
+# define local_lock_acquire(__ll)  do { typecheck(local_lock_t *, __ll); } while (0)
+# define local_lock_release(__ll)  do { typecheck(local_lock_t *, __ll); } while (0)
+# define local_lock_debug_init(__ll)  do { typecheck(local_lock_t *, __ll); } while (0)
 #endif /* !CONFIG_DEBUG_LOCK_ALLOC */
 
 #define INIT_LOCAL_LOCK(lockname)	{ LOCAL_LOCK_DEBUG_INIT(lockname) }
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index e490b84732d16..c9e883104adb1 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3669,8 +3669,18 @@ u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp,
 void generic_xdp_tx(struct sk_buff *skb, struct bpf_prog *xdp_prog);
 int do_xdp_generic(struct bpf_prog *xdp_prog, struct sk_buff *skb);
 int netif_rx(struct sk_buff *skb);
-int netif_rx_ni(struct sk_buff *skb);
-int netif_rx_any_context(struct sk_buff *skb);
+int __netif_rx(struct sk_buff *skb);
+
+static inline int netif_rx_ni(struct sk_buff *skb)
+{
+	return netif_rx(skb);
+}
+
+static inline int netif_rx_any_context(struct sk_buff *skb)
+{
+	return netif_rx(skb);
+}
+
 int netif_receive_skb(struct sk_buff *skb);
 int netif_receive_skb_core(struct sk_buff *skb);
 void netif_receive_skb_list_internal(struct list_head *head);
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 728cb0c1f0b6d..e3404a736c72a 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -1686,7 +1686,7 @@ struct nfs_unlinkdata {
 	struct nfs_removeargs args;
 	struct nfs_removeres res;
 	struct dentry *dentry;
-	wait_queue_head_t wq;
+	struct swait_queue_head wq;
 	const struct cred *cred;
 	struct nfs_fattr dir_attr;
 	long timeout;
diff --git a/include/linux/preempt.h b/include/linux/preempt.h
index b4381f255a5ca..c05c5247986f7 100644
--- a/include/linux/preempt.h
+++ b/include/linux/preempt.h
@@ -196,6 +196,20 @@ extern void preempt_count_sub(int val);
 #define preempt_count_inc() preempt_count_add(1)
 #define preempt_count_dec() preempt_count_sub(1)
 
+#ifdef CONFIG_PREEMPT_LAZY
+#define add_preempt_lazy_count(val)	do { preempt_lazy_count() += (val); } while (0)
+#define sub_preempt_lazy_count(val)	do { preempt_lazy_count() -= (val); } while (0)
+#define inc_preempt_lazy_count()	add_preempt_lazy_count(1)
+#define dec_preempt_lazy_count()	sub_preempt_lazy_count(1)
+#define preempt_lazy_count()		(current_thread_info()->preempt_lazy_count)
+#else
+#define add_preempt_lazy_count(val)	do { } while (0)
+#define sub_preempt_lazy_count(val)	do { } while (0)
+#define inc_preempt_lazy_count()	do { } while (0)
+#define dec_preempt_lazy_count()	do { } while (0)
+#define preempt_lazy_count()		(0)
+#endif
+
 #ifdef CONFIG_PREEMPT_COUNT
 
 #define preempt_disable() \
@@ -204,13 +218,25 @@ do { \
 	barrier(); \
 } while (0)
 
+#define preempt_lazy_disable() \
+do { \
+	inc_preempt_lazy_count(); \
+	barrier(); \
+} while (0)
+
 #define sched_preempt_enable_no_resched() \
 do { \
 	barrier(); \
 	preempt_count_dec(); \
 } while (0)
 
-#define preempt_enable_no_resched() sched_preempt_enable_no_resched()
+#ifndef CONFIG_PREEMPT_RT
+# define preempt_enable_no_resched() sched_preempt_enable_no_resched()
+# define preempt_check_resched_rt() barrier();
+#else
+# define preempt_enable_no_resched() preempt_enable()
+# define preempt_check_resched_rt() preempt_check_resched()
+#endif
 
 #define preemptible()	(preempt_count() == 0 && !irqs_disabled())
 
@@ -235,6 +261,18 @@ do { \
 		__preempt_schedule(); \
 } while (0)
 
+/*
+ * open code preempt_check_resched() because it is not exported to modules and
+ * used by local_unlock() or bpf_enable_instrumentation().
+ */
+#define preempt_lazy_enable() \
+do { \
+	dec_preempt_lazy_count(); \
+	barrier(); \
+	if (should_resched(0)) \
+		__preempt_schedule(); \
+} while (0)
+
 #else /* !CONFIG_PREEMPTION */
 #define preempt_enable() \
 do { \
@@ -242,6 +280,12 @@ do { \
 	preempt_count_dec(); \
 } while (0)
 
+#define preempt_lazy_enable() \
+do { \
+	dec_preempt_lazy_count(); \
+	barrier(); \
+} while (0)
+
 #define preempt_enable_notrace() \
 do { \
 	barrier(); \
@@ -280,8 +324,12 @@ do { \
 #define preempt_disable_notrace()		barrier()
 #define preempt_enable_no_resched_notrace()	barrier()
 #define preempt_enable_notrace()		barrier()
+#define preempt_check_resched_rt()		barrier()
 #define preemptible()				0
 
+#define preempt_lazy_disable()			barrier()
+#define preempt_lazy_enable()			barrier()
+
 #endif /* CONFIG_PREEMPT_COUNT */
 
 #ifdef MODULE
@@ -300,7 +348,7 @@ do { \
 } while (0)
 #define preempt_fold_need_resched() \
 do { \
-	if (tif_need_resched()) \
+	if (tif_need_resched_now()) \
 		set_preempt_need_resched(); \
 } while (0)
 
@@ -416,8 +464,15 @@ extern void migrate_enable(void);
 
 #else
 
-static inline void migrate_disable(void) { }
-static inline void migrate_enable(void) { }
+static inline void migrate_disable(void)
+{
+	preempt_lazy_disable();
+}
+
+static inline void migrate_enable(void)
+{
+	preempt_lazy_enable();
+}
 
 #endif /* CONFIG_SMP */
 
diff --git a/include/linux/printk.h b/include/linux/printk.h
index 1522df223c0f7..9ce3e5ad58f06 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -170,6 +170,11 @@ extern void __printk_safe_exit(void);
 #define printk_deferred_enter __printk_safe_enter
 #define printk_deferred_exit __printk_safe_exit
 
+extern void printk_direct_enter(void);
+extern void printk_direct_exit(void);
+
+extern bool pr_flush(int timeout_ms, bool reset_on_progress);
+
 /*
  * Please don't use printk_ratelimit(), because it shares ratelimiting state
  * with all other unrelated printk_ratelimit() callsites.  Instead use
@@ -220,6 +225,19 @@ static inline void printk_deferred_exit(void)
 {
 }
 
+static inline void printk_direct_enter(void)
+{
+}
+
+static inline void printk_direct_exit(void)
+{
+}
+
+static inline bool pr_flush(int timeout_ms, bool reset_on_progress)
+{
+	return true;
+}
+
 static inline int printk_ratelimit(void)
 {
 	return 0;
@@ -277,45 +295,45 @@ static inline void printk_trigger_flush(void)
 #endif
 
 #ifdef CONFIG_SMP
-extern int __printk_cpu_trylock(void);
-extern void __printk_wait_on_cpu_lock(void);
-extern void __printk_cpu_unlock(void);
+extern int __printk_cpu_sync_try_get(void);
+extern void __printk_cpu_sync_wait(void);
+extern void __printk_cpu_sync_put(void);
+
+#else
+
+#define __printk_cpu_sync_try_get() true
+#define __printk_cpu_sync_wait()
+#define __printk_cpu_sync_put()
+#endif /* CONFIG_SMP */
 
 /**
- * printk_cpu_lock_irqsave() - Acquire the printk cpu-reentrant spinning
- *                             lock and disable interrupts.
+ * printk_cpu_sync_get_irqsave() - Disable interrupts and acquire the printk
+ *                                 cpu-reentrant spinning lock.
  * @flags: Stack-allocated storage for saving local interrupt state,
- *         to be passed to printk_cpu_unlock_irqrestore().
+ *         to be passed to printk_cpu_sync_put_irqrestore().
  *
  * If the lock is owned by another CPU, spin until it becomes available.
  * Interrupts are restored while spinning.
  */
-#define printk_cpu_lock_irqsave(flags)		\
-	for (;;) {				\
-		local_irq_save(flags);		\
-		if (__printk_cpu_trylock())	\
-			break;			\
-		local_irq_restore(flags);	\
-		__printk_wait_on_cpu_lock();	\
+#define printk_cpu_sync_get_irqsave(flags)		\
+	for (;;) {					\
+		local_irq_save(flags);			\
+		if (__printk_cpu_sync_try_get())	\
+			break;				\
+		local_irq_restore(flags);		\
+		__printk_cpu_sync_wait();		\
 	}
 
 /**
- * printk_cpu_unlock_irqrestore() - Release the printk cpu-reentrant spinning
- *                                  lock and restore interrupts.
- * @flags: Caller's saved interrupt state, from printk_cpu_lock_irqsave().
+ * printk_cpu_sync_put_irqrestore() - Release the printk cpu-reentrant spinning
+ *                                    lock and restore interrupts.
+ * @flags: Caller's saved interrupt state, from printk_cpu_sync_get_irqsave().
  */
-#define printk_cpu_unlock_irqrestore(flags)	\
+#define printk_cpu_sync_put_irqrestore(flags)	\
 	do {					\
-		__printk_cpu_unlock();		\
+		__printk_cpu_sync_put();	\
 		local_irq_restore(flags);	\
-	} while (0)				\
-
-#else
-
-#define printk_cpu_lock_irqsave(flags) ((void)flags)
-#define printk_cpu_unlock_irqrestore(flags) ((void)flags)
-
-#endif /* CONFIG_SMP */
+	} while (0)
 
 extern int kptr_restrict;
 
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 88b42eb464068..8b3874d68a174 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -95,6 +95,13 @@ void rcu_init_tasks_generic(void);
 static inline void rcu_init_tasks_generic(void) { }
 #endif
 
+#if defined(CONFIG_PROVE_RCU) && defined(CONFIG_TASKS_RCU_GENERIC)
+void rcu_tasks_initiate_self_tests(void);
+#else
+static inline void rcu_tasks_initiate_self_tests(void) {}
+#endif
+
+
 #ifdef CONFIG_RCU_STALL_COMMON
 void rcu_sysrq_start(void);
 void rcu_sysrq_end(void);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index f5b2be39a78cb..80070768a69d3 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -118,12 +118,8 @@ struct task_group;
 
 #define task_is_running(task)		(READ_ONCE((task)->__state) == TASK_RUNNING)
 
-#define task_is_traced(task)		((READ_ONCE(task->__state) & __TASK_TRACED) != 0)
-
 #define task_is_stopped(task)		((READ_ONCE(task->__state) & __TASK_STOPPED) != 0)
 
-#define task_is_stopped_or_traced(task)	((READ_ONCE(task->__state) & (__TASK_STOPPED | __TASK_TRACED)) != 0)
-
 /*
  * Special states are those that do not use the normal wait-loop pattern. See
  * the comment with set_special_state().
@@ -1087,6 +1083,10 @@ struct task_struct {
 	/* Restored if set_restore_sigmask() was used: */
 	sigset_t			saved_sigmask;
 	struct sigpending		pending;
+#ifdef CONFIG_PREEMPT_RT
+	/* TODO: move me into ->restart_block ? */
+	struct				kernel_siginfo forced_info;
+#endif
 	unsigned long			sas_ss_sp;
 	size_t				sas_ss_size;
 	unsigned int			sas_ss_flags;
@@ -2007,6 +2007,118 @@ static inline int test_tsk_need_resched(struct task_struct *tsk)
 	return unlikely(test_tsk_thread_flag(tsk,TIF_NEED_RESCHED));
 }
 
+#ifdef CONFIG_PREEMPT_LAZY
+static inline void set_tsk_need_resched_lazy(struct task_struct *tsk)
+{
+	set_tsk_thread_flag(tsk,TIF_NEED_RESCHED_LAZY);
+}
+
+static inline void clear_tsk_need_resched_lazy(struct task_struct *tsk)
+{
+	clear_tsk_thread_flag(tsk,TIF_NEED_RESCHED_LAZY);
+}
+
+static inline int test_tsk_need_resched_lazy(struct task_struct *tsk)
+{
+	return unlikely(test_tsk_thread_flag(tsk,TIF_NEED_RESCHED_LAZY));
+}
+
+static inline int need_resched_lazy(void)
+{
+	return test_thread_flag(TIF_NEED_RESCHED_LAZY);
+}
+
+static inline int need_resched_now(void)
+{
+	return test_thread_flag(TIF_NEED_RESCHED);
+}
+
+#else
+static inline void clear_tsk_need_resched_lazy(struct task_struct *tsk) { }
+static inline int need_resched_lazy(void) { return 0; }
+
+static inline int need_resched_now(void)
+{
+	return test_thread_flag(TIF_NEED_RESCHED);
+}
+
+#endif
+
+#ifdef CONFIG_PREEMPT_RT
+static inline bool task_match_saved_state(struct task_struct *p, long match_state)
+{
+	return p->saved_state == match_state;
+}
+
+static inline bool task_is_traced(struct task_struct *task)
+{
+	bool traced = false;
+
+	/* in case the task is sleeping on tasklist_lock */
+	raw_spin_lock_irq(&task->pi_lock);
+	if (READ_ONCE(task->__state) & __TASK_TRACED)
+		traced = true;
+	else if (task->saved_state & __TASK_TRACED)
+		traced = true;
+	raw_spin_unlock_irq(&task->pi_lock);
+	return traced;
+}
+
+static inline bool task_is_stopped_or_traced(struct task_struct *task)
+{
+	bool traced_stopped = false;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&task->pi_lock, flags);
+
+	if (READ_ONCE(task->__state) & (__TASK_STOPPED | __TASK_TRACED))
+		traced_stopped = true;
+	else if (task->saved_state & (__TASK_STOPPED | __TASK_TRACED))
+		traced_stopped = true;
+
+	raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+	return traced_stopped;
+}
+
+#else
+
+static inline bool task_match_saved_state(struct task_struct *p, long match_state)
+{
+	return false;
+}
+
+static inline bool task_is_traced(struct task_struct *task)
+{
+	return READ_ONCE(task->__state) & __TASK_TRACED;
+}
+
+static inline bool task_is_stopped_or_traced(struct task_struct *task)
+{
+	return READ_ONCE(task->__state) & (__TASK_STOPPED | __TASK_TRACED);
+}
+#endif
+
+static inline bool task_match_state_or_saved(struct task_struct *p,
+					     long match_state)
+{
+	if (READ_ONCE(p->__state) == match_state)
+		return true;
+
+	return task_match_saved_state(p, match_state);
+}
+
+static inline bool task_match_state_lock(struct task_struct *p,
+					 long match_state)
+{
+	bool match;
+
+	raw_spin_lock_irq(&p->pi_lock);
+	match = task_match_state_or_saved(p, match_state);
+	raw_spin_unlock_irq(&p->pi_lock);
+
+	return match;
+}
+
 /*
  * cond_resched() and cond_resched_lock(): latency reduction via
  * explicit rescheduling in places that are safe. The return
diff --git a/include/linux/sched/task_stack.h b/include/linux/sched/task_stack.h
index d10150587d819..ccd1336aa7f42 100644
--- a/include/linux/sched/task_stack.h
+++ b/include/linux/sched/task_stack.h
@@ -70,6 +70,7 @@ static inline void *try_get_task_stack(struct task_struct *tsk)
 }
 
 extern void put_task_stack(struct task_struct *tsk);
+extern void put_task_stack_sched(struct task_struct *tsk);
 #else
 static inline void *try_get_task_stack(struct task_struct *tsk)
 {
@@ -77,8 +78,17 @@ static inline void *try_get_task_stack(struct task_struct *tsk)
 }
 
 static inline void put_task_stack(struct task_struct *tsk) {}
+static inline void put_task_stack_sched(struct task_struct *tsk) {}
 #endif
 
+#ifdef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
+static inline void task_stack_cleanup(struct task_struct *tsk) {}
+#else
+extern void task_stack_cleanup(struct task_struct *tsk);
+#endif
+
+void exit_task_stack_account(struct task_struct *tsk);
+
 #define task_stack_end_corrupted(task) \
 		(*(end_of_stack(task)) != STACK_END_MAGIC)
 
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index ff84a3ed10ea9..875907fd43b29 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -7,6 +7,7 @@
 #ifndef _LINUX_SERIAL_8250_H
 #define _LINUX_SERIAL_8250_H
 
+#include <linux/atomic.h>
 #include <linux/serial_core.h>
 #include <linux/serial_reg.h>
 #include <linux/platform_device.h>
@@ -123,6 +124,8 @@ struct uart_8250_port {
 #define MSR_SAVE_FLAGS UART_MSR_ANY_DELTA
 	unsigned char		msr_saved_flags;
 
+	atomic_t		console_printing;
+
 	struct uart_8250_dma	*dma;
 	const struct uart_8250_ops *ops;
 
@@ -178,6 +181,8 @@ void serial8250_init_port(struct uart_8250_port *up);
 void serial8250_set_defaults(struct uart_8250_port *up);
 void serial8250_console_write(struct uart_8250_port *up, const char *s,
 			      unsigned int count);
+void serial8250_console_write_atomic(struct uart_8250_port *up, const char *s,
+				     unsigned int count);
 int serial8250_console_setup(struct uart_port *port, char *options, bool probe);
 int serial8250_console_exit(struct uart_port *port);
 
diff --git a/include/linux/smp.h b/include/linux/smp.h
index a80ab58ae3f1d..dd3441d8af448 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -267,6 +267,9 @@ static inline int get_boot_cpu_id(void)
 #define get_cpu()		({ preempt_disable(); __smp_processor_id(); })
 #define put_cpu()		preempt_enable()
 
+#define get_cpu_light()		({ migrate_disable(); __smp_processor_id(); })
+#define put_cpu_light()		migrate_enable()
+
 /*
  * Callback to arch code if there's nosmp or maxcpus=0 on the
  * boot command line:
diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
index 73a6f34b3847a..93c188c8cecea 100644
--- a/include/linux/thread_info.h
+++ b/include/linux/thread_info.h
@@ -177,7 +177,17 @@ static __always_inline unsigned long read_ti_thread_flags(struct thread_info *ti
 	clear_ti_thread_flag(task_thread_info(t), TIF_##fl)
 #endif /* !CONFIG_GENERIC_ENTRY */
 
-#define tif_need_resched() test_thread_flag(TIF_NEED_RESCHED)
+#ifdef CONFIG_PREEMPT_LAZY
+#define tif_need_resched()	(test_thread_flag(TIF_NEED_RESCHED) || \
+				 test_thread_flag(TIF_NEED_RESCHED_LAZY))
+#define tif_need_resched_now()	(test_thread_flag(TIF_NEED_RESCHED))
+#define tif_need_resched_lazy()	test_thread_flag(TIF_NEED_RESCHED_LAZY)
+
+#else
+#define tif_need_resched()	test_thread_flag(TIF_NEED_RESCHED)
+#define tif_need_resched_now()	test_thread_flag(TIF_NEED_RESCHED)
+#define tif_need_resched_lazy()	0
+#endif
 
 #ifndef CONFIG_HAVE_ARCH_WITHIN_STACK_FRAMES
 static inline int arch_within_stack_frames(const void * const stack,
diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 70c069aef02ca..609ea6d36daa9 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -69,6 +69,7 @@ struct trace_entry {
 	unsigned char		flags;
 	unsigned char		preempt_count;
 	int			pid;
+	unsigned char		preempt_lazy_count;
 };
 
 #define TRACE_EVENT_TYPE_MAX						\
@@ -157,9 +158,10 @@ static inline void tracing_generic_entry_update(struct trace_entry *entry,
 						unsigned int trace_ctx)
 {
 	entry->preempt_count		= trace_ctx & 0xff;
+	entry->preempt_lazy_count	= (trace_ctx >> 16) & 0xff;
 	entry->pid			= current->pid;
 	entry->type			= type;
-	entry->flags =			trace_ctx >> 16;
+	entry->flags			= trace_ctx >> 24;
 }
 
 unsigned int tracing_gen_ctx_irq_test(unsigned int irqs_status);
@@ -170,7 +172,13 @@ enum trace_flag_type {
 	TRACE_FLAG_NEED_RESCHED		= 0x04,
 	TRACE_FLAG_HARDIRQ		= 0x08,
 	TRACE_FLAG_SOFTIRQ		= 0x10,
+#ifdef CONFIG_PREEMPT_LAZY
+	TRACE_FLAG_PREEMPT_RESCHED	= 0x00,
+	TRACE_FLAG_NEED_RESCHED_LAZY	= 0x20,
+#else
+	TRACE_FLAG_NEED_RESCHED_LAZY	= 0x00,
 	TRACE_FLAG_PREEMPT_RESCHED	= 0x20,
+#endif
 	TRACE_FLAG_NMI			= 0x40,
 	TRACE_FLAG_BH_OFF		= 0x80,
 };
diff --git a/include/trace/events/net.h b/include/trace/events/net.h
index 78c448c6ab4c5..032b431b987b6 100644
--- a/include/trace/events/net.h
+++ b/include/trace/events/net.h
@@ -260,13 +260,6 @@ DEFINE_EVENT(net_dev_rx_verbose_template, netif_rx_entry,
 	TP_ARGS(skb)
 );
 
-DEFINE_EVENT(net_dev_rx_verbose_template, netif_rx_ni_entry,
-
-	TP_PROTO(const struct sk_buff *skb),
-
-	TP_ARGS(skb)
-);
-
 DECLARE_EVENT_CLASS(net_dev_rx_exit_template,
 
 	TP_PROTO(int ret),
@@ -312,13 +305,6 @@ DEFINE_EVENT(net_dev_rx_exit_template, netif_rx_exit,
 	TP_ARGS(ret)
 );
 
-DEFINE_EVENT(net_dev_rx_exit_template, netif_rx_ni_exit,
-
-	TP_PROTO(int ret),
-
-	TP_ARGS(ret)
-);
-
 DEFINE_EVENT(net_dev_rx_exit_template, netif_receive_skb_list_exit,
 
 	TP_PROTO(int ret),
diff --git a/include/trace/events/random.h b/include/trace/events/random.h
index a2d9aa16a5d7a..01d60208f0064 100644
--- a/include/trace/events/random.h
+++ b/include/trace/events/random.h
@@ -52,12 +52,6 @@ DEFINE_EVENT(random__mix_pool_bytes, mix_pool_bytes,
 	TP_ARGS(bytes, IP)
 );
 
-DEFINE_EVENT(random__mix_pool_bytes, mix_pool_bytes_nolock,
-	TP_PROTO(int bytes, unsigned long IP),
-
-	TP_ARGS(bytes, IP)
-);
-
 TRACE_EVENT(credit_entropy_bits,
 	TP_PROTO(int bits, int entropy_count, unsigned long IP),
 
diff --git a/init/Kconfig b/init/Kconfig
index e9119bf54b1f3..c75a369d871bd 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1541,6 +1541,10 @@ config PRINTK
 	  very difficult to diagnose system problems, saying N here is
 	  strongly discouraged.
 
+config HAVE_ATOMIC_CONSOLE
+	bool
+	default n
+
 config BUG
 	bool "BUG() support" if EXPERT
 	default y
@@ -2054,6 +2058,7 @@ source "arch/Kconfig"
 
 config RT_MUTEXES
 	bool
+	default y if PREEMPT_RT
 
 config BASE_SMALL
 	int
diff --git a/init/main.c b/init/main.c
index 65fa2e41a9c09..cfc45e47b9ca4 100644
--- a/init/main.c
+++ b/init/main.c
@@ -1600,6 +1600,7 @@ static noinline void __init kernel_init_freeable(void)
 
 	rcu_init_tasks_generic();
 	do_pre_smp_initcalls();
+	rcu_tasks_initiate_self_tests();
 	lockup_detector_init();
 
 	smp_init();
diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt
index ce77f02656603..5d3e650cdf489 100644
--- a/kernel/Kconfig.preempt
+++ b/kernel/Kconfig.preempt
@@ -1,5 +1,11 @@
 # SPDX-License-Identifier: GPL-2.0-only
 
+config HAVE_PREEMPT_LAZY
+	bool
+
+config PREEMPT_LAZY
+	def_bool y if HAVE_PREEMPT_LAZY && PREEMPT_RT
+
 config PREEMPT_NONE_BUILD
 	bool
 
diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
index 9d331ba44870a..53b771c20ee50 100644
--- a/kernel/cgroup/rstat.c
+++ b/kernel/cgroup/rstat.c
@@ -153,8 +153,9 @@ static void cgroup_rstat_flush_locked(struct cgroup *cgrp, bool may_sleep)
 		raw_spinlock_t *cpu_lock = per_cpu_ptr(&cgroup_rstat_cpu_lock,
 						       cpu);
 		struct cgroup *pos = NULL;
+		unsigned long flags;
 
-		raw_spin_lock(cpu_lock);
+		raw_spin_lock_irqsave(cpu_lock, flags);
 		while ((pos = cgroup_rstat_cpu_pop_updated(pos, cgrp, cpu))) {
 			struct cgroup_subsys_state *css;
 
@@ -166,7 +167,7 @@ static void cgroup_rstat_flush_locked(struct cgroup *cgrp, bool may_sleep)
 				css->ss->css_rstat_flush(css, cpu);
 			rcu_read_unlock();
 		}
-		raw_spin_unlock(cpu_lock);
+		raw_spin_unlock_irqrestore(cpu_lock, flags);
 
 		/* if @may_sleep, play nice and yield if necessary */
 		if (may_sleep && (need_resched() ||
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index bad713684c2e3..93ad647f4a220 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -159,9 +159,17 @@ static unsigned long exit_to_user_mode_loop(struct pt_regs *regs,
 
 		local_irq_enable_exit_to_user(ti_work);
 
-		if (ti_work & _TIF_NEED_RESCHED)
+		if (ti_work & _TIF_NEED_RESCHED_MASK)
 			schedule();
 
+#ifdef ARCH_RT_DELAYS_SIGNAL_SEND
+		if (unlikely(current->forced_info.si_signo)) {
+			struct task_struct *t = current;
+			force_sig_info(&t->forced_info);
+			t->forced_info.si_signo = 0;
+		}
+#endif
+
 		if (ti_work & _TIF_UPROBE)
 			uprobe_notify_resume(regs);
 
@@ -387,7 +395,7 @@ void irqentry_exit_cond_resched(void)
 		rcu_irq_exit_check_preempt();
 		if (IS_ENABLED(CONFIG_DEBUG_ENTRY))
 			WARN_ON_ONCE(!on_thread_stack());
-		if (need_resched())
+		if (should_resched(0))
 			preempt_schedule_irq();
 	}
 }
diff --git a/kernel/exit.c b/kernel/exit.c
index b00a25bb4ab93..293b280d23192 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -171,6 +171,7 @@ static void delayed_put_task_struct(struct rcu_head *rhp)
 	kprobe_flush_task(tsk);
 	perf_event_delayed_put(tsk);
 	trace_sched_process_free(tsk);
+	task_stack_cleanup(tsk);
 	put_task_struct(tsk);
 }
 
@@ -845,6 +846,7 @@ void __noreturn do_exit(long code)
 		put_page(tsk->task_frag.page);
 
 	validate_creds_for_do_exit(tsk);
+	exit_task_stack_account(tsk);
 
 	check_stack_usage();
 	preempt_disable();
diff --git a/kernel/fork.c b/kernel/fork.c
index d75a528f7b219..92cafad00c653 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -179,13 +179,23 @@ static inline void free_task_struct(struct task_struct *tsk)
 
 #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
 
+#define THREAD_STACK_DELAYED_FREE	1UL
+
+static void thread_stack_mark_delayed_free(struct task_struct *tsk)
+{
+	unsigned long val = (unsigned long)tsk->stack;
+
+	val |= THREAD_STACK_DELAYED_FREE;
+	WRITE_ONCE(tsk->stack, (void *)val);
+}
+
 /*
  * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
  * kmemcache based allocator.
  */
 # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
 
-#ifdef CONFIG_VMAP_STACK
+#  ifdef CONFIG_VMAP_STACK
 /*
  * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
  * flush.  Try to minimize the number of calls by caching stacks.
@@ -210,11 +220,35 @@ static int free_vm_stack_cache(unsigned int cpu)
 
 	return 0;
 }
-#endif
 
-static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
+static int memcg_charge_kernel_stack(struct vm_struct *vm)
 {
-#ifdef CONFIG_VMAP_STACK
+	int i;
+	int ret;
+
+	BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0);
+	BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
+
+	for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
+		ret = memcg_kmem_charge_page(vm->pages[i], GFP_KERNEL, 0);
+		if (ret)
+			goto err;
+	}
+	return 0;
+err:
+	/*
+	 * If memcg_kmem_charge_page() fails, page's memory cgroup pointer is
+	 * NULL, and memcg_kmem_uncharge_page() in free_thread_stack() will
+	 * ignore this page.
+	 */
+	for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
+		memcg_kmem_uncharge_page(vm->pages[i], 0);
+	return ret;
+}
+
+static int alloc_thread_stack_node(struct task_struct *tsk, int node)
+{
+	struct vm_struct *vm;
 	void *stack;
 	int i;
 
@@ -232,9 +266,14 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
 		/* Clear stale pointers from reused stack. */
 		memset(s->addr, 0, THREAD_SIZE);
 
+		if (memcg_charge_kernel_stack(s)) {
+			vfree(s->addr);
+			return -ENOMEM;
+		}
+
 		tsk->stack_vm_area = s;
 		tsk->stack = s->addr;
-		return s->addr;
+		return 0;
 	}
 
 	/*
@@ -247,71 +286,93 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
 				     THREADINFO_GFP & ~__GFP_ACCOUNT,
 				     PAGE_KERNEL,
 				     0, node, __builtin_return_address(0));
+	if (!stack)
+		return -ENOMEM;
 
+	vm = find_vm_area(stack);
+	if (memcg_charge_kernel_stack(vm)) {
+		vfree(stack);
+		return -ENOMEM;
+	}
 	/*
 	 * We can't call find_vm_area() in interrupt context, and
 	 * free_thread_stack() can be called in interrupt context,
 	 * so cache the vm_struct.
 	 */
-	if (stack) {
-		tsk->stack_vm_area = find_vm_area(stack);
-		tsk->stack = stack;
+	tsk->stack_vm_area = vm;
+	tsk->stack = stack;
+	return 0;
+}
+
+static void free_thread_stack(struct task_struct *tsk, bool cache_only)
+{
+	int i;
+
+	for (i = 0; i < NR_CACHED_STACKS; i++) {
+		if (this_cpu_cmpxchg(cached_stacks[i], NULL,
+				     tsk->stack_vm_area) != NULL)
+			continue;
+
+		tsk->stack = NULL;
+		tsk->stack_vm_area = NULL;
+		return;
 	}
-	return stack;
-#else
+	if (cache_only) {
+		thread_stack_mark_delayed_free(tsk);
+		return;
+	}
+
+	vfree(tsk->stack);
+	tsk->stack = NULL;
+	tsk->stack_vm_area = NULL;
+}
+
+#  else /* !CONFIG_VMAP_STACK */
+
+static int alloc_thread_stack_node(struct task_struct *tsk, int node)
+{
 	struct page *page = alloc_pages_node(node, THREADINFO_GFP,
 					     THREAD_SIZE_ORDER);
 
 	if (likely(page)) {
 		tsk->stack = kasan_reset_tag(page_address(page));
-		return tsk->stack;
+		return 0;
 	}
-	return NULL;
-#endif
+	return -ENOMEM;
 }
 
-static inline void free_thread_stack(struct task_struct *tsk)
+static void free_thread_stack(struct task_struct *tsk, bool cache_only)
 {
-#ifdef CONFIG_VMAP_STACK
-	struct vm_struct *vm = task_stack_vm_area(tsk);
-
-	if (vm) {
-		int i;
-
-		for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
-			memcg_kmem_uncharge_page(vm->pages[i], 0);
-
-		for (i = 0; i < NR_CACHED_STACKS; i++) {
-			if (this_cpu_cmpxchg(cached_stacks[i],
-					NULL, tsk->stack_vm_area) != NULL)
-				continue;
-
-			return;
-		}
-
-		vfree_atomic(tsk->stack);
+	if (cache_only) {
+		thread_stack_mark_delayed_free(tsk);
 		return;
 	}
-#endif
-
 	__free_pages(virt_to_page(tsk->stack), THREAD_SIZE_ORDER);
+	tsk->stack = NULL;
 }
-# else
+
+#  endif /* CONFIG_VMAP_STACK */
+# else /* !(THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)) */
+
 static struct kmem_cache *thread_stack_cache;
 
-static unsigned long *alloc_thread_stack_node(struct task_struct *tsk,
-						  int node)
+static int alloc_thread_stack_node(struct task_struct *tsk, int node)
 {
 	unsigned long *stack;
 	stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node);
 	stack = kasan_reset_tag(stack);
 	tsk->stack = stack;
-	return stack;
+	return stack ? 0 : -ENOMEM;
 }
 
-static void free_thread_stack(struct task_struct *tsk)
+static void free_thread_stack(struct task_struct *tsk, bool cache_only)
 {
+	if (cache_only) {
+		thread_stack_mark_delayed_free(tsk);
+		return;
+	}
 	kmem_cache_free(thread_stack_cache, tsk->stack);
+	tsk->stack = NULL;
 }
 
 void thread_stack_cache_init(void)
@@ -321,8 +382,36 @@ void thread_stack_cache_init(void)
 					THREAD_SIZE, NULL);
 	BUG_ON(thread_stack_cache == NULL);
 }
-# endif
-#endif
+
+# endif /* THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK) */
+
+void task_stack_cleanup(struct task_struct *tsk)
+{
+	unsigned long val = (unsigned long)tsk->stack;
+
+	if (!(val & THREAD_STACK_DELAYED_FREE))
+		return;
+
+	WRITE_ONCE(tsk->stack, (void *)(val & ~THREAD_STACK_DELAYED_FREE));
+	free_thread_stack(tsk, false);
+}
+
+#else /* CONFIG_ARCH_THREAD_STACK_ALLOCATOR */
+static int alloc_thread_stack_node(struct task_struct *tsk, int node)
+{
+	unsigned long *stack;
+
+	stack = arch_alloc_thread_stack_node(tsk, node);
+	tsk->stack = stack;
+	return stack ? 0 : -ENOMEM;
+}
+
+static void free_thread_stack(struct task_struct *tsk, bool cache_only)
+{
+	arch_free_thread_stack(tsk);
+}
+
+#endif /* !CONFIG_ARCH_THREAD_STACK_ALLOCATOR */
 
 /* SLAB cache for signal_struct structures (tsk->signal) */
 static struct kmem_cache *signal_cachep;
@@ -379,70 +468,55 @@ void vm_area_free(struct vm_area_struct *vma)
 
 static void account_kernel_stack(struct task_struct *tsk, int account)
 {
-	void *stack = task_stack_page(tsk);
-	struct vm_struct *vm = task_stack_vm_area(tsk);
-
-	if (vm) {
+	if (IS_ENABLED(CONFIG_VMAP_STACK)) {
+		struct vm_struct *vm = task_stack_vm_area(tsk);
 		int i;
 
 		for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
 			mod_lruvec_page_state(vm->pages[i], NR_KERNEL_STACK_KB,
 					      account * (PAGE_SIZE / 1024));
 	} else {
+		void *stack = task_stack_page(tsk);
+
 		/* All stack pages are in the same node. */
 		mod_lruvec_kmem_state(stack, NR_KERNEL_STACK_KB,
 				      account * (THREAD_SIZE / 1024));
 	}
 }
 
-static int memcg_charge_kernel_stack(struct task_struct *tsk)
+void exit_task_stack_account(struct task_struct *tsk)
 {
-#ifdef CONFIG_VMAP_STACK
-	struct vm_struct *vm = task_stack_vm_area(tsk);
-	int ret;
+	account_kernel_stack(tsk, -1);
 
-	BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0);
-
-	if (vm) {
+	if (IS_ENABLED(CONFIG_VMAP_STACK)) {
+		struct vm_struct *vm;
 		int i;
 
-		BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
-
-		for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
-			/*
-			 * If memcg_kmem_charge_page() fails, page's
-			 * memory cgroup pointer is NULL, and
-			 * memcg_kmem_uncharge_page() in free_thread_stack()
-			 * will ignore this page.
-			 */
-			ret = memcg_kmem_charge_page(vm->pages[i], GFP_KERNEL,
-						     0);
-			if (ret)
-				return ret;
-		}
+		vm = task_stack_vm_area(tsk);
+		for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
+			memcg_kmem_uncharge_page(vm->pages[i], 0);
 	}
-#endif
-	return 0;
 }
 
-static void release_task_stack(struct task_struct *tsk)
+static void release_task_stack(struct task_struct *tsk, bool cache_only)
 {
 	if (WARN_ON(READ_ONCE(tsk->__state) != TASK_DEAD))
 		return;  /* Better to leak the stack than to free prematurely */
 
-	account_kernel_stack(tsk, -1);
-	free_thread_stack(tsk);
-	tsk->stack = NULL;
-#ifdef CONFIG_VMAP_STACK
-	tsk->stack_vm_area = NULL;
-#endif
+	free_thread_stack(tsk, cache_only);
 }
 
 #ifdef CONFIG_THREAD_INFO_IN_TASK
 void put_task_stack(struct task_struct *tsk)
 {
 	if (refcount_dec_and_test(&tsk->stack_refcount))
-		release_task_stack(tsk);
+		release_task_stack(tsk, false);
+}
+
+void put_task_stack_sched(struct task_struct *tsk)
+{
+	if (refcount_dec_and_test(&tsk->stack_refcount))
+		release_task_stack(tsk, true);
 }
 #endif
 
@@ -456,7 +530,7 @@ void free_task(struct task_struct *tsk)
 	 * The task is finally done with both the stack and thread_info,
 	 * so free both.
 	 */
-	release_task_stack(tsk);
+	release_task_stack(tsk, false);
 #else
 	/*
 	 * If the task had a separate stack allocation, it should be gone
@@ -874,8 +948,6 @@ void set_task_stack_end_magic(struct task_struct *tsk)
 static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
 {
 	struct task_struct *tsk;
-	unsigned long *stack;
-	struct vm_struct *stack_vm_area __maybe_unused;
 	int err;
 
 	if (node == NUMA_NO_NODE)
@@ -884,32 +956,18 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
 	if (!tsk)
 		return NULL;
 
-	stack = alloc_thread_stack_node(tsk, node);
-	if (!stack)
+	err = arch_dup_task_struct(tsk, orig);
+	if (err)
 		goto free_tsk;
 
-	if (memcg_charge_kernel_stack(tsk))
-		goto free_stack;
+	err = alloc_thread_stack_node(tsk, node);
+	if (err)
+		goto free_tsk;
 
-	stack_vm_area = task_stack_vm_area(tsk);
-
-	err = arch_dup_task_struct(tsk, orig);
-
-	/*
-	 * arch_dup_task_struct() clobbers the stack-related fields.  Make
-	 * sure they're properly initialized before using any stack-related
-	 * functions again.
-	 */
-	tsk->stack = stack;
-#ifdef CONFIG_VMAP_STACK
-	tsk->stack_vm_area = stack_vm_area;
-#endif
 #ifdef CONFIG_THREAD_INFO_IN_TASK
 	refcount_set(&tsk->stack_refcount, 1);
 #endif
-
-	if (err)
-		goto free_stack;
+	account_kernel_stack(tsk, 1);
 
 	err = scs_prepare(tsk, node);
 	if (err)
@@ -953,8 +1011,6 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
 	tsk->wake_q.next = NULL;
 	tsk->worker_private = NULL;
 
-	account_kernel_stack(tsk, 1);
-
 	kcov_task_init(tsk);
 	kmap_local_fork(tsk);
 
@@ -973,7 +1029,8 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
 	return tsk;
 
 free_stack:
-	free_thread_stack(tsk);
+	exit_task_stack_account(tsk);
+	free_thread_stack(tsk, false);
 free_tsk:
 	free_task_struct(tsk);
 	return NULL;
@@ -2441,6 +2498,7 @@ static __latent_entropy struct task_struct *copy_process(
 	exit_creds(p);
 bad_fork_free:
 	WRITE_ONCE(p->__state, TASK_DEAD);
+	exit_task_stack_account(p);
 	put_task_stack(p);
 	delayed_free_task(p);
 fork_out:
diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 52501e5f76554..bbfbccf69275e 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -127,6 +127,8 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
 	 * complain:
 	 */
 	if (sysctl_hung_task_warnings) {
+		printk_direct_enter();
+
 		if (sysctl_hung_task_warnings > 0)
 			sysctl_hung_task_warnings--;
 		pr_err("INFO: task %s:%d blocked for more than %ld seconds.\n",
@@ -142,6 +144,8 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
 
 		if (sysctl_hung_task_all_cpu_backtrace)
 			hung_task_show_all_bt = true;
+
+		printk_direct_exit();
 	}
 
 	touch_nmi_watchdog();
@@ -204,12 +208,17 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout)
 	}
  unlock:
 	rcu_read_unlock();
-	if (hung_task_show_lock)
+	if (hung_task_show_lock) {
+		printk_direct_enter();
 		debug_show_all_locks();
+		printk_direct_exit();
+	}
 
 	if (hung_task_show_all_bt) {
 		hung_task_show_all_bt = false;
+		printk_direct_enter();
 		trigger_all_cpu_backtrace();
+		printk_direct_exit();
 	}
 
 	if (hung_task_call_panic)
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 2267e6527db3c..97223df2f460e 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -662,6 +662,27 @@ int generic_handle_irq(unsigned int irq)
 }
 EXPORT_SYMBOL_GPL(generic_handle_irq);
 
+/**
+ * generic_handle_irq_safe - Invoke the handler for a particular irq
+ * @irq:	The irq number to handle
+ *
+ * Returns:	0 on success, or -EINVAL if conversion has failed
+ *
+ * This function must be called either from an IRQ context with irq regs
+ * initialized or with care from any context.
+ */
+int generic_handle_irq_safe(unsigned int irq)
+{
+	unsigned long flags;
+	int ret;
+
+	local_irq_save(flags);
+	ret = handle_irq_desc(irq_to_desc(irq));
+	local_irq_restore(flags);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(generic_handle_irq_safe);
+
 #ifdef CONFIG_IRQ_DOMAIN
 /**
  * generic_handle_domain_irq - Invoke the handler for a HW irq belonging
diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index 35859da8bd4f7..dfff31ed644a6 100644
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -138,6 +138,15 @@ KERNEL_ATTR_RO(vmcoreinfo);
 
 #endif /* CONFIG_CRASH_CORE */
 
+#if defined(CONFIG_PREEMPT_RT)
+static ssize_t realtime_show(struct kobject *kobj,
+			     struct kobj_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%d\n", 1);
+}
+KERNEL_ATTR_RO(realtime);
+#endif
+
 /* whether file capabilities are enabled */
 static ssize_t fscaps_show(struct kobject *kobj,
 				  struct kobj_attribute *attr, char *buf)
@@ -228,6 +237,9 @@ static struct attribute * kernel_attrs[] = {
 #ifndef CONFIG_TINY_RCU
 	&rcu_expedited_attr.attr,
 	&rcu_normal_attr.attr,
+#endif
+#ifdef CONFIG_PREEMPT_RT
+	&realtime_attr.attr,
 #endif
 	NULL
 };
diff --git a/kernel/panic.c b/kernel/panic.c
index 55b50e052ec3a..ee7e26d93b410 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -216,7 +216,6 @@ void panic(const char *fmt, ...)
 		panic_smp_self_stop();
 
 	console_verbose();
-	bust_spinlocks(1);
 	va_start(args, fmt);
 	len = vscnprintf(buf, sizeof(buf), fmt, args);
 	va_end(args);
@@ -233,6 +232,11 @@ void panic(const char *fmt, ...)
 		dump_stack();
 #endif
 
+	/* If atomic consoles are available, flush the kernel log. */
+	console_flush_on_panic(CONSOLE_ATOMIC_FLUSH_PENDING);
+
+	bust_spinlocks(1);
+
 	/*
 	 * If kgdb is enabled, give it a chance to run before we stop all
 	 * the other CPUs or else we won't be able to debug processes left
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 82abfaf3c2aad..3bef5100312ea 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -44,6 +44,7 @@
 #include <linux/irq_work.h>
 #include <linux/ctype.h>
 #include <linux/uio.h>
+#include <linux/clocksource.h>
 #include <linux/sched/clock.h>
 #include <linux/sched/debug.h>
 #include <linux/sched/task_stack.h>
@@ -215,6 +216,26 @@ int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write,
 /* Number of registered extended console drivers. */
 static int nr_ext_console_drivers;
 
+/*
+ * Used to synchronize printing kthreads against direct printing via
+ * console_trylock/console_unlock.
+ *
+ * Values:
+ * -1 = console locked (via trylock), kthreads will not print
+ *  0 = no kthread printing, console not locked (via trylock)
+ * >0 = kthread(s) actively printing
+ *
+ * Note: For synchronizing against direct printing via
+ *       console_lock/console_unlock, see the @lock variable in
+ *       struct console.
+ */
+static atomic_t console_lock_count = ATOMIC_INIT(0);
+
+#define console_excl_trylock() (atomic_cmpxchg(&console_lock_count, 0, -1) == 0)
+#define console_excl_unlock() atomic_cmpxchg(&console_lock_count, -1, 0)
+#define console_printer_tryenter() atomic_inc_unless_negative(&console_lock_count)
+#define console_printer_exit() atomic_dec(&console_lock_count)
+
 /*
  * Helper macros to handle lockdep when locking/unlocking console_sem. We use
  * macros instead of functions so that _RET_IP_ contains useful information.
@@ -258,19 +279,37 @@ static void __up_console_sem(unsigned long ip)
 #define up_console_sem() __up_console_sem(_RET_IP_)
 
 /*
- * This is used for debugging the mess that is the VT code by
- * keeping track if we have the console semaphore held. It's
- * definitely not the perfect debug tool (we don't know if _WE_
- * hold it and are racing, but it helps tracking those weird code
- * paths in the console code where we end up in places I want
- * locked without the console semaphore held).
+ * Tracks whether kthread printers are all paused. A value of true implies
+ * that the console is locked via console_lock() or the console is suspended.
+ * Reading and writing to this variable requires holding @console_sem.
  */
-static int console_locked, console_suspended;
+static bool consoles_paused;
 
 /*
- * If exclusive_console is non-NULL then only this console is to be printed to.
+ * Pause or unpause all kthread printers.
+ *
+ * Requires the console_lock.
  */
-static struct console *exclusive_console;
+static void __pause_all_consoles(bool do_pause)
+{
+	struct console *con;
+
+	for_each_console(con) {
+		mutex_lock(&con->lock);
+		if (do_pause)
+			con->flags |= CON_PAUSED;
+		else
+			con->flags &= ~CON_PAUSED;
+		mutex_unlock(&con->lock);
+	}
+
+	consoles_paused = do_pause;
+}
+
+#define pause_all_consoles() __pause_all_consoles(true)
+#define unpause_all_consoles() __pause_all_consoles(false)
+
+static int console_suspended;
 
 /*
  *	Array of consoles built from command line options (console=)
@@ -353,7 +392,47 @@ static int console_msg_format = MSG_FORMAT_DEFAULT;
 /* syslog_lock protects syslog_* variables and write access to clear_seq. */
 static DEFINE_MUTEX(syslog_lock);
 
+/*
+ * A flag to signify if printk_late_init() has already started the kthread
+ * printers. If true, any later registered consoles must start their own
+ * kthread directly. The flag is write protected by the console_lock.
+ */
+static bool kthreads_started;
+
 #ifdef CONFIG_PRINTK
+static atomic_t printk_direct = ATOMIC_INIT(0);
+
+/**
+ * printk_direct_enter - cause console printing to occur in the context of
+ * 	printk() callers
+ *
+ * This globally effects all printk() callers.
+ *
+ * Context: Any context.
+ */
+void printk_direct_enter(void)
+{
+	atomic_inc(&printk_direct);
+}
+
+/**
+ * printk_direct_exit - restore console printing behavior from direct
+ *
+ * Context: Any context.
+ */
+void printk_direct_exit(void)
+{
+	atomic_dec(&printk_direct);
+}
+
+static inline bool allow_direct_printing(void)
+{
+	return (!kthreads_started ||
+		system_state != SYSTEM_RUNNING ||
+		oops_in_progress ||
+		atomic_read(&printk_direct));
+}
+
 DECLARE_WAIT_QUEUE_HEAD(log_wait);
 /* All 3 protected by @syslog_lock. */
 /* the next printk record to read by syslog(READ) or /proc/kmsg */
@@ -361,12 +440,6 @@ static u64 syslog_seq;
 static size_t syslog_partial;
 static bool syslog_time;
 
-/* All 3 protected by @console_sem. */
-/* the next printk record to write to the console */
-static u64 console_seq;
-static u64 exclusive_console_stop_seq;
-static unsigned long console_dropped;
-
 struct latched_seq {
 	seqcount_latch_t	latch;
 	u64			val[2];
@@ -392,6 +465,9 @@ static struct latched_seq clear_seq = {
 /* the maximum size of a formatted record (i.e. with prefix added per line) */
 #define CONSOLE_LOG_MAX		1024
 
+/* the maximum size for a dropped text message */
+#define DROPPED_TEXT_MAX	64
+
 /* the maximum size allowed to be reserved for a record */
 #define LOG_LINE_MAX		(CONSOLE_LOG_MAX - PREFIX_MAX)
 
@@ -1823,6 +1899,7 @@ static int console_lock_spinning_disable_and_check(void)
 	return 1;
 }
 
+#if !IS_ENABLED(CONFIG_PREEMPT_RT)
 /**
  * console_trylock_spinning - try to get console_lock by busy waiting
  *
@@ -1886,49 +1963,38 @@ static int console_trylock_spinning(void)
 
 	return 1;
 }
+#endif /* CONFIG_PREEMPT_RT */
 
 /*
- * Call the console drivers, asking them to write out
- * log_buf[start] to log_buf[end - 1].
- * The console_lock must be held.
+ * Call the specified console driver, asking it to write out the specified
+ * text and length. If @dropped_text is non-NULL and any records have been
+ * dropped, a dropped message will be written out first.
  */
-static void call_console_drivers(const char *ext_text, size_t ext_len,
-				 const char *text, size_t len)
+static void call_console_driver(struct console *con, const char *text, size_t len,
+				char *dropped_text, bool atomic_printing)
 {
-	static char dropped_text[64];
-	size_t dropped_len = 0;
-	struct console *con;
+	unsigned long dropped = 0;
+	size_t dropped_len;
 
 	trace_console_rcuidle(text, len);
 
-	if (!console_drivers)
-		return;
+	if (dropped_text)
+		dropped = atomic_long_xchg_relaxed(&con->dropped, 0);
 
-	if (console_dropped) {
-		dropped_len = snprintf(dropped_text, sizeof(dropped_text),
+	if (dropped) {
+		dropped_len = snprintf(dropped_text, DROPPED_TEXT_MAX,
 				       "** %lu printk messages dropped **\n",
-				       console_dropped);
-		console_dropped = 0;
+				       dropped);
+		if (atomic_printing)
+			con->write_atomic(con, dropped_text, dropped_len);
+		else
+			con->write(con, dropped_text, dropped_len);
 	}
 
-	for_each_console(con) {
-		if (exclusive_console && con != exclusive_console)
-			continue;
-		if (!(con->flags & CON_ENABLED))
-			continue;
-		if (!con->write)
-			continue;
-		if (!cpu_online(smp_processor_id()) &&
-		    !(con->flags & CON_ANYTIME))
-			continue;
-		if (con->flags & CON_EXTENDED)
-			con->write(con, ext_text, ext_len);
-		else {
-			if (dropped_len)
-				con->write(con, dropped_text, dropped_len);
-			con->write(con, text, len);
-		}
-	}
+	if (atomic_printing)
+		con->write_atomic(con, text, len);
+	else
+		con->write(con, text, len);
 }
 
 /*
@@ -2003,8 +2069,10 @@ static u8 *__printk_recursion_counter(void)
 
 int printk_delay_msec __read_mostly;
 
-static inline void printk_delay(void)
+static inline void printk_delay(int level)
 {
+	boot_delay_msec(level);
+
 	if (unlikely(printk_delay_msec)) {
 		int m = printk_delay_msec;
 
@@ -2018,7 +2086,7 @@ static inline void printk_delay(void)
 static inline u32 printk_caller_id(void)
 {
 	return in_task() ? task_pid_nr(current) :
-		0x80000000 + raw_smp_processor_id();
+		0x80000000 + smp_processor_id();
 }
 
 /**
@@ -2100,7 +2168,6 @@ int vprintk_store(int facility, int level,
 		  const struct dev_printk_info *dev_info,
 		  const char *fmt, va_list args)
 {
-	const u32 caller_id = printk_caller_id();
 	struct prb_reserved_entry e;
 	enum printk_info_flags flags = 0;
 	struct printk_record r;
@@ -2110,10 +2177,14 @@ int vprintk_store(int facility, int level,
 	u8 *recursion_ptr;
 	u16 reserve_size;
 	va_list args2;
+	u32 caller_id;
 	u16 text_len;
 	int ret = 0;
 	u64 ts_nsec;
 
+	if (!printk_enter_irqsave(recursion_ptr, irqflags))
+		return 0;
+
 	/*
 	 * Since the duration of printk() can vary depending on the message
 	 * and state of the ringbuffer, grab the timestamp now so that it is
@@ -2122,8 +2193,7 @@ int vprintk_store(int facility, int level,
 	 */
 	ts_nsec = local_clock();
 
-	if (!printk_enter_irqsave(recursion_ptr, irqflags))
-		return 0;
+	caller_id = printk_caller_id();
 
 	/*
 	 * The sprintf needs to come first since the syslog prefix might be
@@ -2223,27 +2293,36 @@ asmlinkage int vprintk_emit(int facility, int level,
 		in_sched = true;
 	}
 
-	boot_delay_msec(level);
-	printk_delay();
-
 	printed_len = vprintk_store(facility, level, dev_info, fmt, args);
 
 	/* If called from the scheduler, we can not call up(). */
-	if (!in_sched) {
+	if (!in_sched && allow_direct_printing()) {
+		/*
+		 * Try to acquire and then immediately release the console
+		 * semaphore.  The release will print out buffers.
+		 */
+#if IS_ENABLED(CONFIG_PREEMPT_RT)
+		/*
+		 * Use the non-spinning trylock since PREEMPT_RT does not
+		 * support console lock handovers.
+		 *
+		 * Direct printing will most likely involve taking spinlocks.
+		 * For PREEMPT_RT, this is only allowed if in a preemptible
+		 * context.
+		 */
+		if (preemptible() && console_trylock())
+			console_unlock();
+#else
 		/*
 		 * Disable preemption to avoid being preempted while holding
 		 * console_sem which would prevent anyone from printing to
 		 * console
 		 */
 		preempt_disable();
-		/*
-		 * Try to acquire and then immediately release the console
-		 * semaphore.  The release will print out buffers and wake up
-		 * /dev/kmsg and syslog() users.
-		 */
 		if (console_trylock_spinning())
 			console_unlock();
 		preempt_enable();
+#endif
 	}
 
 	wake_up_klogd();
@@ -2270,18 +2349,91 @@ asmlinkage __visible int _printk(const char *fmt, ...)
 }
 EXPORT_SYMBOL(_printk);
 
+#ifdef CONFIG_HAVE_ATOMIC_CONSOLE
+static void __free_atomic_data(struct console_atomic_data *d)
+{
+	kfree(d->text);
+	kfree(d->ext_text);
+	kfree(d->dropped_text);
+}
+
+static void free_atomic_data(struct console_atomic_data *d)
+{
+	int count = 1;
+	int i;
+
+	if (!d)
+		return;
+
+#ifdef CONFIG_HAVE_NMI
+	count = 2;
+#endif
+
+	for (i = 0; i < count; i++)
+		__free_atomic_data(&d[i]);
+	kfree(d);
+}
+
+static int __alloc_atomic_data(struct console_atomic_data *d, short flags)
+{
+	d->text = kmalloc(CONSOLE_LOG_MAX, GFP_KERNEL);
+	if (!d->text)
+		return -1;
+
+	if (flags & CON_EXTENDED) {
+		d->ext_text = kmalloc(CONSOLE_EXT_LOG_MAX, GFP_KERNEL);
+		if (!d->ext_text)
+			return -1;
+	} else {
+		d->dropped_text = kmalloc(DROPPED_TEXT_MAX, GFP_KERNEL);
+		if (!d->dropped_text)
+			return -1;
+	}
+
+	return 0;
+}
+
+static struct console_atomic_data *alloc_atomic_data(short flags)
+{
+	struct console_atomic_data *d;
+	int count = 1;
+	int i;
+
+#ifdef CONFIG_HAVE_NMI
+	count = 2;
+#endif
+
+	d = kzalloc(sizeof(*d) * count, GFP_KERNEL);
+	if (!d)
+		goto err_out;
+
+	for (i = 0; i < count; i++) {
+		if (__alloc_atomic_data(&d[i], flags) != 0)
+			goto err_out;
+	}
+
+	return d;
+err_out:
+	free_atomic_data(d);
+	return NULL;
+}
+#endif /* CONFIG_HAVE_ATOMIC_CONSOLE */
+
+static void start_printk_kthread(struct console *con);
+
 #else /* CONFIG_PRINTK */
 
 #define CONSOLE_LOG_MAX		0
+#define DROPPED_TEXT_MAX	0
 #define printk_time		false
 
 #define prb_read_valid(rb, seq, r)	false
 #define prb_first_valid_seq(rb)		0
+#define prb_next_seq(rb)		0
+
+#define free_atomic_data(d)
 
 static u64 syslog_seq;
-static u64 console_seq;
-static u64 exclusive_console_stop_seq;
-static unsigned long console_dropped;
 
 static size_t record_print_text(const struct printk_record *r,
 				bool syslog, bool time)
@@ -2298,9 +2450,12 @@ static ssize_t msg_print_ext_body(char *buf, size_t size,
 				  struct dev_printk_info *dev_info) { return 0; }
 static void console_lock_spinning_enable(void) { }
 static int console_lock_spinning_disable_and_check(void) { return 0; }
-static void call_console_drivers(const char *ext_text, size_t ext_len,
-				 const char *text, size_t len) {}
+static void call_console_driver(struct console *con, const char *text, size_t len,
+				char *dropped_text, bool atomic_printing) {}
 static bool suppress_message_printing(int level) { return false; }
+static void printk_delay(int level) {}
+static void start_printk_kthread(struct console *con) {}
+static bool allow_direct_printing(void) { return true; }
 
 #endif /* CONFIG_PRINTK */
 
@@ -2476,6 +2631,7 @@ void suspend_console(void)
 	if (!console_suspend_enabled)
 		return;
 	pr_info("Suspending console(s) (use no_console_suspend to debug)\n");
+	pr_flush(1000, true);
 	console_lock();
 	console_suspended = 1;
 	up_console_sem();
@@ -2488,6 +2644,7 @@ void resume_console(void)
 	down_console_sem();
 	console_suspended = 0;
 	console_unlock();
+	pr_flush(1000, true);
 }
 
 /**
@@ -2524,7 +2681,7 @@ void console_lock(void)
 	down_console_sem();
 	if (console_suspended)
 		return;
-	console_locked = 1;
+	pause_all_consoles();
 	console_may_schedule = 1;
 }
 EXPORT_SYMBOL(console_lock);
@@ -2545,46 +2702,411 @@ int console_trylock(void)
 		up_console_sem();
 		return 0;
 	}
-	console_locked = 1;
+	if (!console_excl_trylock()) {
+		up_console_sem();
+		return 0;
+	}
 	console_may_schedule = 0;
 	return 1;
 }
 EXPORT_SYMBOL(console_trylock);
 
+/*
+ * A variant of console_trylock() that allows specifying if the context may
+ * sleep. If yes, a trylock on @console_sem is attempted and if successful,
+ * the threaded printers are paused. This is important to ensure that
+ * sleepable contexts do not become involved in console_lock handovers and
+ * will call cond_resched() during the printing loop.
+ */
+static int console_trylock_sched(bool may_schedule)
+{
+	if (!may_schedule)
+		return console_trylock();
+
+	might_sleep();
+
+	if (down_trylock_console_sem())
+		return 0;
+	if (console_suspended) {
+		up_console_sem();
+		return 0;
+	}
+	pause_all_consoles();
+	console_may_schedule = 1;
+	return 1;
+}
+
+/*
+ * This is used to help to make sure that certain paths within the VT code are
+ * running with the console lock held. It is definitely not the perfect debug
+ * tool (it is not known if the VT code is the task holding the console lock),
+ * but it helps tracking those weird code paths in the console code such as
+ * when the console is suspended: where the console is not locked but no
+ * console printing may occur.
+ *
+ * Note: This returns true when the console is suspended but is not locked.
+ *       This is intentional because the VT code must consider that situation
+ *       the same as if the console was locked.
+ */
 int is_console_locked(void)
 {
-	return console_locked;
+	return (consoles_paused || atomic_read(&console_lock_count));
 }
 EXPORT_SYMBOL(is_console_locked);
 
 /*
- * Check if we have any console that is capable of printing while cpu is
- * booting or shutting down. Requires console_sem.
+ * Check if the given console is currently capable and allowed to print
+ * records.
+ *
+ * Requires the console_lock.
  */
-static int have_callable_console(void)
+static inline bool console_is_usable(struct console *con, bool atomic_printing)
 {
-	struct console *con;
+	if (!(con->flags & CON_ENABLED))
+		return false;
 
-	for_each_console(con)
-		if ((con->flags & CON_ENABLED) &&
-				(con->flags & CON_ANYTIME))
-			return 1;
+	if (atomic_printing) {
+#ifdef CONFIG_HAVE_ATOMIC_CONSOLE
+		if (!con->write_atomic)
+			return false;
+		if (!con->atomic_data)
+			return false;
+#else
+		return false;
+#endif
+	} else if (!con->write) {
+		return false;
+	}
 
-	return 0;
+	/*
+	 * Console drivers may assume that per-cpu resources have been
+	 * allocated. So unless they're explicitly marked as being able to
+	 * cope (CON_ANYTIME) don't call them until per-cpu resources have
+	 * been allocated.
+	 */
+	if (!printk_percpu_data_ready() &&
+	    !(con->flags & CON_ANYTIME))
+		return false;
+
+	return true;
+}
+
+static void __console_unlock(void)
+{
+	/*
+	 * Depending on whether console_lock() or console_trylock() was used,
+	 * appropriately allow the kthread printers to continue.
+	 */
+	if (consoles_paused)
+		unpause_all_consoles();
+	else
+		console_excl_unlock();
+
+	/* Wake the kthread printers. */
+	wake_up_klogd();
+
+	up_console_sem();
+}
+
+static u64 read_console_seq(struct console *con)
+{
+#ifdef CONFIG_HAVE_ATOMIC_CONSOLE
+	unsigned long flags;
+	u64 seq2;
+	u64 seq;
+
+	if (!con->atomic_data)
+		return con->seq;
+
+	printk_cpu_sync_get_irqsave(flags);
+
+	seq = con->seq;
+	seq2 = con->atomic_data[0].seq;
+	if (seq2 > seq)
+		seq = seq2;
+#ifdef CONFIG_HAVE_NMI
+	seq2 = con->atomic_data[1].seq;
+	if (seq2 > seq)
+		seq = seq2;
+#endif
+
+	printk_cpu_sync_put_irqrestore(flags);
+
+	return seq;
+#else /* CONFIG_HAVE_ATOMIC_CONSOLE */
+	return con->seq;
+#endif
+}
+
+static void write_console_seq(struct console *con, u64 val, bool atomic_printing)
+{
+#ifdef CONFIG_HAVE_ATOMIC_CONSOLE
+	unsigned long flags;
+	u64 *seq;
+
+	if (!con->atomic_data) {
+		con->seq = val;
+		return;
+	}
+
+	printk_cpu_sync_get_irqsave(flags);
+
+	if (atomic_printing) {
+		seq = &con->atomic_data[0].seq;
+#ifdef CONFIG_HAVE_NMI
+		if (in_nmi())
+			seq = &con->atomic_data[1].seq;
+#endif
+	} else {
+		seq = &con->seq;
+	}
+	*seq = val;
+
+	printk_cpu_sync_put_irqrestore(flags);
+#else /* CONFIG_HAVE_ATOMIC_CONSOLE */
+	con->seq = val;
+#endif
 }
 
 /*
- * Can we actually use the console at this time on this cpu?
+ * Print one record for the given console. The record printed is whatever
+ * record is the next available record for the given console.
  *
- * Console drivers may assume that per-cpu resources have been allocated. So
- * unless they're explicitly marked as being able to cope (CON_ANYTIME) don't
- * call them until this CPU is officially up.
+ * @text is a buffer of size CONSOLE_LOG_MAX.
+ *
+ * If extended messages should be printed, @ext_text is a buffer of size
+ * CONSOLE_EXT_LOG_MAX. Otherwise @ext_text must be NULL.
+ *
+ * If dropped messages should be printed, @dropped_text is a buffer of size
+ * DROPPED_TEXT_MAX. Otherise @dropped_text must be NULL.
+ *
+ * @atomic_printing specifies if atomic printing should be used.
+ *
+ * Requires the console_lock.
+ *
+ * Returns false if the given console has no next record to print, otherwise
+ * true.
+ *
+ * @handover will be set to true if a printk waiter has taken over the
+ * console_lock, in which case the caller is no longer holding the
+ * console_lock. Otherwise it is set to false. A NULL pointer may be provided
+ * to disable allowing the console_lock to be taken over by a printk waiter.
  */
-static inline int can_use_console(void)
+static bool console_emit_next_record(struct console *con, char *text, char *ext_text,
+				     char *dropped_text, bool atomic_printing,
+				     bool *handover)
 {
-	return cpu_online(raw_smp_processor_id()) || have_callable_console();
+	struct printk_info info;
+	struct printk_record r;
+	unsigned long flags;
+	bool allow_handover;
+	char *write_text;
+	size_t len;
+	u64 seq;
+
+	prb_rec_init_rd(&r, &info, text, CONSOLE_LOG_MAX);
+
+	if (handover)
+		*handover = false;
+
+	seq = read_console_seq(con);
+
+	if (!prb_read_valid(prb, seq, &r))
+		return false;
+
+	if (seq != r.info->seq) {
+		atomic_long_add((unsigned long)(r.info->seq - seq), &con->dropped);
+		write_console_seq(con, r.info->seq, atomic_printing);
+		seq = r.info->seq;
+	}
+
+	/* Skip record that has level above the console loglevel. */
+	if (suppress_message_printing(r.info->level)) {
+		write_console_seq(con, seq + 1, atomic_printing);
+		goto skip;
+	}
+
+	if (ext_text) {
+		write_text = ext_text;
+		len = info_print_ext_header(ext_text, CONSOLE_EXT_LOG_MAX, r.info);
+		len += msg_print_ext_body(ext_text + len, CONSOLE_EXT_LOG_MAX - len,
+					  &r.text_buf[0], r.info->text_len, &r.info->dev_info);
+	} else {
+		write_text = text;
+		len = record_print_text(&r, console_msg_format & MSG_FORMAT_SYSLOG, printk_time);
+	}
+
+#if IS_ENABLED(CONFIG_PREEMPT_RT)
+	/* PREEMPT_RT does not support console lock handovers. */
+	allow_handover = false;
+#else
+	/* Handovers may only happen between trylock contexts. */
+	allow_handover = (handover && atomic_read(&console_lock_count) == -1);
+#endif
+
+	if (allow_handover) {
+		/*
+		 * While actively printing out messages, if another printk()
+		 * were to occur on another CPU, it may wait for this one to
+		 * finish. This task can not be preempted if there is a
+		 * waiter waiting to take over.
+		 *
+		 * Interrupts are disabled because the hand over to a waiter
+		 * must not be interrupted until the hand over is completed
+		 * (@console_waiter is cleared).
+		 */
+		printk_safe_enter_irqsave(flags);
+		console_lock_spinning_enable();
+	}
+
+	stop_critical_timings();	/* don't trace print latency */
+	call_console_driver(con, write_text, len, dropped_text, atomic_printing);
+	start_critical_timings();
+
+	write_console_seq(con, seq + 1, atomic_printing);
+
+	if (allow_handover) {
+		*handover = console_lock_spinning_disable_and_check();
+		printk_safe_exit_irqrestore(flags);
+	}
+
+	printk_delay(r.info->level);
+skip:
+	return true;
 }
 
+/*
+ * Print out all remaining records to all consoles.
+ *
+ * Requires the console_lock.
+ *
+ * Returns true if a console was available for flushing, otherwise false.
+ *
+ * @next_seq is set to the highest sequence number of all of the consoles that
+ * were flushed.
+ *
+ * @handover will be set to true if a printk waiter has taken over the
+ * console_lock, in which case the caller is no longer holding the
+ * console_lock. Otherwise it is set to false.
+ */
+static bool console_flush_all(bool do_cond_resched, u64 *next_seq, bool *handover)
+{
+	static char dropped_text[DROPPED_TEXT_MAX];
+	static char ext_text[CONSOLE_EXT_LOG_MAX];
+	static char text[CONSOLE_LOG_MAX];
+	bool any_usable = false;
+	struct console *con;
+	bool any_progress;
+
+	*next_seq = 0;
+	*handover = false;
+
+	do {
+		/* Let the kthread printers do the work if they can. */
+		if (!allow_direct_printing())
+			break;
+
+		any_progress = false;
+
+		for_each_console(con) {
+			bool progress;
+
+			if (!console_is_usable(con, false))
+				continue;
+			if ((con->flags & CON_MIGHT_SLEEP) && !do_cond_resched)
+				continue;
+			any_usable = true;
+
+			if (con->flags & CON_EXTENDED) {
+				/* Extended consoles do not print "dropped messages". */
+				progress = console_emit_next_record(con, &text[0],
+								    &ext_text[0], NULL,
+								    false, handover);
+			} else {
+				progress = console_emit_next_record(con, &text[0],
+								    NULL, &dropped_text[0],
+								    false, handover);
+			}
+			if (*handover)
+				return true;
+
+			/* Track the highest seq flushed. */
+			if (con->seq > *next_seq)
+				*next_seq = con->seq;
+
+			if (!progress)
+				continue;
+			any_progress = true;
+
+			if (do_cond_resched)
+				cond_resched();
+		}
+	} while (any_progress);
+
+	return any_usable;
+}
+
+#ifdef CONFIG_HAVE_ATOMIC_CONSOLE
+static void atomic_console_flush_all(void)
+{
+	bool any_usable = false;
+	unsigned long flags;
+	struct console *con;
+	bool any_progress;
+	int index = 0;
+
+	if (console_suspended)
+		return;
+
+#ifdef CONFIG_HAVE_NMI
+	if (in_nmi())
+		index = 1;
+#endif
+
+	printk_cpu_sync_get_irqsave(flags);
+
+	do {
+		any_progress = false;
+
+		for_each_console(con) {
+			bool progress;
+
+			if (!console_is_usable(con, true))
+				continue;
+			any_usable = true;
+
+			if (con->flags & CON_EXTENDED) {
+				/* Extended consoles do not print "dropped messages". */
+				progress = console_emit_next_record(con,
+							&con->atomic_data->text[index],
+							&con->atomic_data->ext_text[index],
+							NULL,
+							true, NULL);
+			} else {
+				progress = console_emit_next_record(con,
+							&con->atomic_data->text[index],
+							NULL,
+							&con->atomic_data->dropped_text[index],
+							true, NULL);
+			}
+
+			if (!progress)
+				continue;
+			any_progress = true;
+
+			touch_softlockup_watchdog_sync();
+			clocksource_touch_watchdog();
+			rcu_cpu_stall_reset();
+			touch_nmi_watchdog();
+		}
+	} while (any_progress);
+
+	printk_cpu_sync_put_irqrestore(flags);
+}
+#else /* CONFIG_HAVE_ATOMIC_CONSOLE */
+#define atomic_console_flush_all()
+#endif
+
 /**
  * console_unlock - unlock the console system
  *
@@ -2601,21 +3123,16 @@ static inline int can_use_console(void)
  */
 void console_unlock(void)
 {
-	static char ext_text[CONSOLE_EXT_LOG_MAX];
-	static char text[CONSOLE_LOG_MAX];
-	unsigned long flags;
-	bool do_cond_resched, retry;
-	struct printk_info info;
-	struct printk_record r;
-	u64 __maybe_unused next_seq;
+	bool do_cond_resched;
+	bool handover;
+	bool flushed;
+	u64 next_seq;
 
 	if (console_suspended) {
 		up_console_sem();
 		return;
 	}
 
-	prb_rec_init_rd(&r, &info, text, sizeof(text));
-
 	/*
 	 * Console drivers are called with interrupts disabled, so
 	 * @console_may_schedule should be cleared before; however, we may
@@ -2624,117 +3141,31 @@ void console_unlock(void)
 	 * between lines if allowable.  Not doing so can cause a very long
 	 * scheduling stall on a slow console leading to RCU stall and
 	 * softlockup warnings which exacerbate the issue with more
-	 * messages practically incapacitating the system.
-	 *
-	 * console_trylock() is not able to detect the preemptive
-	 * context reliably. Therefore the value must be stored before
-	 * and cleared after the "again" goto label.
+	 * messages practically incapacitating the system. Therefore, create
+	 * a local to use for the printing loop.
 	 */
 	do_cond_resched = console_may_schedule;
-again:
-	console_may_schedule = 0;
 
-	/*
-	 * We released the console_sem lock, so we need to recheck if
-	 * cpu is online and (if not) is there at least one CON_ANYTIME
-	 * console.
-	 */
-	if (!can_use_console()) {
-		console_locked = 0;
-		up_console_sem();
-		return;
-	}
+	do {
+		console_may_schedule = 0;
 
-	for (;;) {
-		size_t ext_len = 0;
-		int handover;
-		size_t len;
-
-skip:
-		if (!prb_read_valid(prb, console_seq, &r))
+		flushed = console_flush_all(do_cond_resched, &next_seq, &handover);
+		if (handover)
 			break;
 
-		if (console_seq != r.info->seq) {
-			console_dropped += r.info->seq - console_seq;
-			console_seq = r.info->seq;
-		}
+		__console_unlock();
 
-		if (suppress_message_printing(r.info->level)) {
-			/*
-			 * Skip record we have buffered and already printed
-			 * directly to the console when we received it, and
-			 * record that has level above the console loglevel.
-			 */
-			console_seq++;
-			goto skip;
-		}
-
-		/* Output to all consoles once old messages replayed. */
-		if (unlikely(exclusive_console &&
-			     console_seq >= exclusive_console_stop_seq)) {
-			exclusive_console = NULL;
-		}
+		/* Were there any consoles available for flushing? */
+		if (!flushed)
+			break;
 
 		/*
-		 * Handle extended console text first because later
-		 * record_print_text() will modify the record buffer in-place.
+		 * Some context may have added new records after
+		 * console_flush_all() but before unlocking the console.
+		 * Re-check if there is a new record to flush. If the trylock
+		 * fails, another context is already handling the printing.
 		 */
-		if (nr_ext_console_drivers) {
-			ext_len = info_print_ext_header(ext_text,
-						sizeof(ext_text),
-						r.info);
-			ext_len += msg_print_ext_body(ext_text + ext_len,
-						sizeof(ext_text) - ext_len,
-						&r.text_buf[0],
-						r.info->text_len,
-						&r.info->dev_info);
-		}
-		len = record_print_text(&r,
-				console_msg_format & MSG_FORMAT_SYSLOG,
-				printk_time);
-		console_seq++;
-
-		/*
-		 * While actively printing out messages, if another printk()
-		 * were to occur on another CPU, it may wait for this one to
-		 * finish. This task can not be preempted if there is a
-		 * waiter waiting to take over.
-		 *
-		 * Interrupts are disabled because the hand over to a waiter
-		 * must not be interrupted until the hand over is completed
-		 * (@console_waiter is cleared).
-		 */
-		printk_safe_enter_irqsave(flags);
-		console_lock_spinning_enable();
-
-		stop_critical_timings();	/* don't trace print latency */
-		call_console_drivers(ext_text, ext_len, text, len);
-		start_critical_timings();
-
-		handover = console_lock_spinning_disable_and_check();
-		printk_safe_exit_irqrestore(flags);
-		if (handover)
-			return;
-
-		if (do_cond_resched)
-			cond_resched();
-	}
-
-	/* Get consistent value of the next-to-be-used sequence number. */
-	next_seq = console_seq;
-
-	console_locked = 0;
-	up_console_sem();
-
-	/*
-	 * Someone could have filled up the buffer again, so re-check if there's
-	 * something to flush. In case we cannot trylock the console_sem again,
-	 * there's a new owner and the console_unlock() from them will do the
-	 * flush, no worries.
-	 */
-	retry = prb_read_valid(prb, next_seq, NULL);
-	if (retry && console_trylock())
-		goto again;
+	} while (prb_read_valid(prb, next_seq, NULL) && console_trylock_sched(do_cond_resched));
 }
 EXPORT_SYMBOL(console_unlock);
 
@@ -2765,10 +3196,15 @@ void console_unblank(void)
 	if (oops_in_progress) {
 		if (down_trylock_console_sem() != 0)
 			return;
-	} else
+		if (!console_excl_trylock()) {
+			up_console_sem();
+			return;
+		}
+	} else {
+		pr_flush(1000, true);
 		console_lock();
+	}
 
-	console_locked = 1;
 	console_may_schedule = 0;
 	for_each_console(c)
 		if ((c->flags & CON_ENABLED) && c->unblank)
@@ -2784,6 +3220,11 @@ void console_unblank(void)
  */
 void console_flush_on_panic(enum con_flush_mode mode)
 {
+	if (mode == CONSOLE_ATOMIC_FLUSH_PENDING) {
+		atomic_console_flush_all();
+		return;
+	}
+
 	/*
 	 * If someone else is holding the console lock, trylock will fail
 	 * and may_schedule may be set.  Ignore and proceed to unlock so
@@ -2794,8 +3235,14 @@ void console_flush_on_panic(enum con_flush_mode mode)
 	console_trylock();
 	console_may_schedule = 0;
 
-	if (mode == CONSOLE_REPLAY_ALL)
-		console_seq = prb_first_valid_seq(prb);
+	if (mode == CONSOLE_REPLAY_ALL) {
+		struct console *c;
+		u64 seq;
+
+		seq = prb_first_valid_seq(prb);
+		for_each_console(c)
+			write_console_seq(c, seq, false);
+	}
 	console_unlock();
 }
 
@@ -2826,6 +3273,7 @@ struct tty_driver *console_device(int *index)
  */
 void console_stop(struct console *console)
 {
+	pr_flush(1000, true);
 	console_lock();
 	console->flags &= ~CON_ENABLED;
 	console_unlock();
@@ -2837,6 +3285,7 @@ void console_start(struct console *console)
 	console_lock();
 	console->flags |= CON_ENABLED;
 	console_unlock();
+	pr_flush(1000, true);
 }
 EXPORT_SYMBOL(console_start);
 
@@ -3030,27 +3479,25 @@ void register_console(struct console *newcon)
 	if (newcon->flags & CON_EXTENDED)
 		nr_ext_console_drivers++;
 
-	if (newcon->flags & CON_PRINTBUFFER) {
-		/*
-		 * console_unlock(); will print out the buffered messages
-		 * for us.
-		 *
-		 * We're about to replay the log buffer.  Only do this to the
-		 * just-registered console to avoid excessive message spam to
-		 * the already-registered consoles.
-		 *
-		 * Set exclusive_console with disabled interrupts to reduce
-		 * race window with eventual console_flush_on_panic() that
-		 * ignores console_lock.
-		 */
-		exclusive_console = newcon;
-		exclusive_console_stop_seq = console_seq;
+	if (consoles_paused)
+		newcon->flags |= CON_PAUSED;
 
+	atomic_long_set(&newcon->dropped, 0);
+#ifdef CONFIG_HAVE_ATOMIC_CONSOLE
+	newcon->atomic_data = NULL;
+#endif
+	mutex_init(&newcon->lock);
+	if (newcon->flags & CON_PRINTBUFFER) {
 		/* Get a consistent copy of @syslog_seq. */
 		mutex_lock(&syslog_lock);
-		console_seq = syslog_seq;
+		write_console_seq(newcon, syslog_seq, false);
 		mutex_unlock(&syslog_lock);
+	} else {
+		/* Begin with next message. */
+		write_console_seq(newcon, prb_next_seq(prb), false);
 	}
+	if (kthreads_started)
+		start_printk_kthread(newcon);
 	console_unlock();
 	console_sysfs_notify();
 
@@ -3107,6 +3554,11 @@ int unregister_console(struct console *console)
 		}
 	}
 
+	if (console->thread) {
+		kthread_stop(console->thread);
+		console->thread = NULL;
+	}
+
 	if (res)
 		goto out_disable_unlock;
 
@@ -3124,6 +3576,10 @@ int unregister_console(struct console *console)
 	console_unlock();
 	console_sysfs_notify();
 
+#ifdef CONFIG_HAVE_ATOMIC_CONSOLE
+	free_atomic_data(console->atomic_data);
+#endif
+
 	if (console->exit)
 		res = console->exit(console);
 
@@ -3213,11 +3669,205 @@ static int __init printk_late_init(void)
 					console_cpu_notify, NULL);
 	WARN_ON(ret < 0);
 	printk_sysctl_init();
+
+	console_lock();
+	for_each_console(con)
+		start_printk_kthread(con);
+	kthreads_started = true;
+	console_unlock();
+
 	return 0;
 }
 late_initcall(printk_late_init);
 
 #if defined CONFIG_PRINTK
+/**
+ * pr_flush() - Wait for printing threads to catch up.
+ *
+ * @timeout_ms:        The maximum time (in ms) to wait.
+ * @reset_on_progress: Reset the timeout if forward progress is seen.
+ *
+ * A value of 0 for @timeout_ms means no waiting will occur. A value of -1
+ * represents infinite waiting.
+ *
+ * If @reset_on_progress is true, the timeout will be reset whenever any
+ * printer has been seen to make some forward progress.
+ *
+ * Context: Process context. May sleep while acquiring console lock.
+ * Return: true if all enabled printers are caught up.
+ */
+bool pr_flush(int timeout_ms, bool reset_on_progress)
+{
+	int remaining = timeout_ms;
+	struct console *con;
+	u64 last_diff = 0;
+	u64 printk_seq;
+	u64 diff;
+	u64 seq;
+
+	might_sleep();
+
+	seq = prb_next_seq(prb);
+
+	for (;;) {
+		diff = 0;
+
+		console_lock();
+		for_each_console(con) {
+			if (!console_is_usable(con, false))
+				continue;
+			printk_seq = con->seq;
+			if (printk_seq < seq)
+				diff += seq - printk_seq;
+		}
+		console_unlock();
+
+		if (diff != last_diff && reset_on_progress)
+			remaining = timeout_ms;
+
+		if (diff == 0 || remaining == 0)
+			break;
+
+		if (remaining < 0) {
+			/* no timeout limit */
+			msleep(100);
+		} else if (remaining < 100) {
+			msleep(remaining);
+			remaining = 0;
+		} else {
+			msleep(100);
+			remaining -= 100;
+		}
+
+		last_diff = diff;
+	}
+
+	return (diff == 0);
+}
+EXPORT_SYMBOL(pr_flush);
+
+static bool printer_should_wake(struct console *con, u64 seq)
+{
+	short flags;
+
+	if (kthread_should_stop())
+		return true;
+
+	/*
+	 * This is an unsafe read to con->flags, but false positives
+	 * are not an issue as long as they are rare.
+	 */
+	flags = data_race(READ_ONCE(con->flags));
+
+	if (!(flags & CON_ENABLED) ||
+	    (flags & CON_PAUSED) ||
+	    atomic_read(&console_lock_count) == -1) {
+		return false;
+	}
+
+	return prb_read_valid(prb, seq, NULL);
+}
+
+static int printk_kthread_func(void *data)
+{
+	struct console *con = data;
+	char *dropped_text = NULL;
+	char *ext_text = NULL;
+	bool progress;
+	u64 seq = 0;
+	char *text;
+	int error;
+
+	pr_info("%sconsole [%s%d]: printing thread started\n",
+		(con->flags & CON_BOOT) ? "boot" : "",
+		con->name, con->index);
+
+#ifdef CONFIG_HAVE_ATOMIC_CONSOLE
+	if (con->write_atomic)
+		con->atomic_data = alloc_atomic_data(con->flags);
+#endif
+
+	text = kmalloc(CONSOLE_LOG_MAX, GFP_KERNEL);
+	if (!text)
+		goto out;
+
+	if (con->flags & CON_EXTENDED) {
+		ext_text = kmalloc(CONSOLE_EXT_LOG_MAX, GFP_KERNEL);
+		if (!ext_text)
+			goto out;
+	} else {
+		dropped_text = kmalloc(DROPPED_TEXT_MAX, GFP_KERNEL);
+		if (!dropped_text)
+			goto out;
+	}
+
+	for (;;) {
+		error = wait_event_interruptible(log_wait, printer_should_wake(con, seq));
+
+		if (kthread_should_stop())
+			break;
+
+		if (error)
+			continue;
+
+		do {
+			error = mutex_lock_interruptible(&con->lock);
+			if (error)
+				break;
+
+			if (!console_is_usable(con, false)) {
+				mutex_unlock(&con->lock);
+				break;
+			}
+
+			if ((con->flags & CON_PAUSED) || !console_printer_tryenter()) {
+				mutex_unlock(&con->lock);
+				break;
+			}
+
+			/*
+			 * Even though the printk kthread is always preemptible, it is
+			 * still not allowed to call cond_resched() from within
+			 * console drivers. The task may become non-preemptible in the
+			 * console driver call chain. For example, vt_console_print()
+			 * takes a spinlock and then can call into fbcon_redraw(),
+			 * which can conditionally invoke cond_resched().
+			 */
+			console_may_schedule = 0;
+			progress = console_emit_next_record(con, text, ext_text,
+							    dropped_text, false, NULL);
+
+			seq = con->seq;
+
+			console_printer_exit();
+
+			mutex_unlock(&con->lock);
+		} while (progress);
+	}
+out:
+	kfree(dropped_text);
+	kfree(ext_text);
+	kfree(text);
+	pr_info("%sconsole [%s%d]: printing thread stopped\n",
+		(con->flags & CON_BOOT) ? "boot" : "",
+		con->name, con->index);
+	return 0;
+}
+
+/* Must be called within console_lock(). */
+static void start_printk_kthread(struct console *con)
+{
+	con->thread = kthread_run(printk_kthread_func, con,
+				  "pr/%s%d", con->name, con->index);
+	if (IS_ERR(con->thread)) {
+		con->thread = NULL;
+		pr_err("%sconsole [%s%d]: unable to start printing thread\n",
+			(con->flags & CON_BOOT) ? "boot" : "",
+			con->name, con->index);
+		return;
+	}
+}
+
 /*
  * Delayed printk version, for scheduler-internal messages:
  */
@@ -3237,7 +3887,7 @@ static void wake_up_klogd_work_func(struct irq_work *irq_work)
 	}
 
 	if (pending & PRINTK_PENDING_WAKEUP)
-		wake_up_interruptible(&log_wait);
+		wake_up_interruptible_all(&log_wait);
 }
 
 static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) =
@@ -3600,26 +4250,26 @@ EXPORT_SYMBOL_GPL(kmsg_dump_rewind);
 #endif
 
 #ifdef CONFIG_SMP
-static atomic_t printk_cpulock_owner = ATOMIC_INIT(-1);
-static atomic_t printk_cpulock_nested = ATOMIC_INIT(0);
+static atomic_t printk_cpu_sync_owner = ATOMIC_INIT(-1);
+static atomic_t printk_cpu_sync_nested = ATOMIC_INIT(0);
 
 /**
- * __printk_wait_on_cpu_lock() - Busy wait until the printk cpu-reentrant
- *                               spinning lock is not owned by any CPU.
+ * __printk_cpu_sync_wait() - Busy wait until the printk cpu-reentrant
+ *                            spinning lock is not owned by any CPU.
  *
  * Context: Any context.
  */
-void __printk_wait_on_cpu_lock(void)
+void __printk_cpu_sync_wait(void)
 {
 	do {
 		cpu_relax();
-	} while (atomic_read(&printk_cpulock_owner) != -1);
+	} while (atomic_read(&printk_cpu_sync_owner) != -1);
 }
-EXPORT_SYMBOL(__printk_wait_on_cpu_lock);
+EXPORT_SYMBOL(__printk_cpu_sync_wait);
 
 /**
- * __printk_cpu_trylock() - Try to acquire the printk cpu-reentrant
- *                          spinning lock.
+ * __printk_cpu_sync_try_get() - Try to acquire the printk cpu-reentrant
+ *                               spinning lock.
  *
  * If no processor has the lock, the calling processor takes the lock and
  * becomes the owner. If the calling processor is already the owner of the
@@ -3628,7 +4278,7 @@ EXPORT_SYMBOL(__printk_wait_on_cpu_lock);
  * Context: Any context. Expects interrupts to be disabled.
  * Return: 1 on success, otherwise 0.
  */
-int __printk_cpu_trylock(void)
+int __printk_cpu_sync_try_get(void)
 {
 	int cpu;
 	int old;
@@ -3638,79 +4288,80 @@ int __printk_cpu_trylock(void)
 	/*
 	 * Guarantee loads and stores from this CPU when it is the lock owner
 	 * are _not_ visible to the previous lock owner. This pairs with
-	 * __printk_cpu_unlock:B.
+	 * __printk_cpu_sync_put:B.
 	 *
 	 * Memory barrier involvement:
 	 *
-	 * If __printk_cpu_trylock:A reads from __printk_cpu_unlock:B, then
-	 * __printk_cpu_unlock:A can never read from __printk_cpu_trylock:B.
+	 * If __printk_cpu_sync_try_get:A reads from __printk_cpu_sync_put:B,
+	 * then __printk_cpu_sync_put:A can never read from
+	 * __printk_cpu_sync_try_get:B.
 	 *
 	 * Relies on:
 	 *
-	 * RELEASE from __printk_cpu_unlock:A to __printk_cpu_unlock:B
+	 * RELEASE from __printk_cpu_sync_put:A to __printk_cpu_sync_put:B
 	 * of the previous CPU
 	 *    matching
-	 * ACQUIRE from __printk_cpu_trylock:A to __printk_cpu_trylock:B
-	 * of this CPU
+	 * ACQUIRE from __printk_cpu_sync_try_get:A to
+	 * __printk_cpu_sync_try_get:B of this CPU
 	 */
-	old = atomic_cmpxchg_acquire(&printk_cpulock_owner, -1,
-				     cpu); /* LMM(__printk_cpu_trylock:A) */
+	old = atomic_cmpxchg_acquire(&printk_cpu_sync_owner, -1,
+				     cpu); /* LMM(__printk_cpu_sync_try_get:A) */
 	if (old == -1) {
 		/*
 		 * This CPU is now the owner and begins loading/storing
-		 * data: LMM(__printk_cpu_trylock:B)
+		 * data: LMM(__printk_cpu_sync_try_get:B)
 		 */
 		return 1;
 
 	} else if (old == cpu) {
 		/* This CPU is already the owner. */
-		atomic_inc(&printk_cpulock_nested);
+		atomic_inc(&printk_cpu_sync_nested);
 		return 1;
 	}
 
 	return 0;
 }
-EXPORT_SYMBOL(__printk_cpu_trylock);
+EXPORT_SYMBOL(__printk_cpu_sync_try_get);
 
 /**
- * __printk_cpu_unlock() - Release the printk cpu-reentrant spinning lock.
+ * __printk_cpu_sync_put() - Release the printk cpu-reentrant spinning lock.
  *
  * The calling processor must be the owner of the lock.
  *
  * Context: Any context. Expects interrupts to be disabled.
  */
-void __printk_cpu_unlock(void)
+void __printk_cpu_sync_put(void)
 {
-	if (atomic_read(&printk_cpulock_nested)) {
-		atomic_dec(&printk_cpulock_nested);
+	if (atomic_read(&printk_cpu_sync_nested)) {
+		atomic_dec(&printk_cpu_sync_nested);
 		return;
 	}
 
 	/*
 	 * This CPU is finished loading/storing data:
-	 * LMM(__printk_cpu_unlock:A)
+	 * LMM(__printk_cpu_sync_put:A)
 	 */
 
 	/*
 	 * Guarantee loads and stores from this CPU when it was the
 	 * lock owner are visible to the next lock owner. This pairs
-	 * with __printk_cpu_trylock:A.
+	 * with __printk_cpu_sync_try_get:A.
 	 *
 	 * Memory barrier involvement:
 	 *
-	 * If __printk_cpu_trylock:A reads from __printk_cpu_unlock:B,
-	 * then __printk_cpu_trylock:B reads from __printk_cpu_unlock:A.
+	 * If __printk_cpu_sync_try_get:A reads from __printk_cpu_sync_put:B,
+	 * then __printk_cpu_sync_try_get:B reads from __printk_cpu_sync_put:A.
 	 *
 	 * Relies on:
 	 *
-	 * RELEASE from __printk_cpu_unlock:A to __printk_cpu_unlock:B
+	 * RELEASE from __printk_cpu_sync_put:A to __printk_cpu_sync_put:B
 	 * of this CPU
 	 *    matching
-	 * ACQUIRE from __printk_cpu_trylock:A to __printk_cpu_trylock:B
-	 * of the next CPU
+	 * ACQUIRE from __printk_cpu_sync_try_get:A to
+	 * __printk_cpu_sync_try_get:B of the next CPU
 	 */
-	atomic_set_release(&printk_cpulock_owner,
-			   -1); /* LMM(__printk_cpu_unlock:B) */
+	atomic_set_release(&printk_cpu_sync_owner,
+			   -1); /* LMM(__printk_cpu_sync_put:B) */
 }
-EXPORT_SYMBOL(__printk_cpu_unlock);
+EXPORT_SYMBOL(__printk_cpu_sync_put);
 #endif /* CONFIG_SMP */
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index eea265082e975..c0d05fe027cf0 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -197,7 +197,18 @@ static bool ptrace_freeze_traced(struct task_struct *task)
 	spin_lock_irq(&task->sighand->siglock);
 	if (task_is_traced(task) && !looks_like_a_spurious_pid(task) &&
 	    !__fatal_signal_pending(task)) {
+#ifdef CONFIG_PREEMPT_RT
+		unsigned long flags;
+
+		raw_spin_lock_irqsave(&task->pi_lock, flags);
+		if (READ_ONCE(task->__state) & __TASK_TRACED)
+			WRITE_ONCE(task->__state, __TASK_TRACED);
+		else
+			task->saved_state = __TASK_TRACED;
+		raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+#else
 		WRITE_ONCE(task->__state, __TASK_TRACED);
+#endif
 		ret = true;
 	}
 	spin_unlock_irq(&task->sighand->siglock);
@@ -207,7 +218,11 @@ static bool ptrace_freeze_traced(struct task_struct *task)
 
 static void ptrace_unfreeze_traced(struct task_struct *task)
 {
-	if (READ_ONCE(task->__state) != __TASK_TRACED)
+	unsigned long flags;
+	bool frozen = true;
+
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT) &&
+	    READ_ONCE(task->__state) != __TASK_TRACED)
 		return;
 
 	WARN_ON(!task->ptrace || task->parent != current);
@@ -217,12 +232,21 @@ static void ptrace_unfreeze_traced(struct task_struct *task)
 	 * Recheck state under the lock to close this race.
 	 */
 	spin_lock_irq(&task->sighand->siglock);
-	if (READ_ONCE(task->__state) == __TASK_TRACED) {
-		if (__fatal_signal_pending(task))
-			wake_up_state(task, __TASK_TRACED);
-		else
-			WRITE_ONCE(task->__state, TASK_TRACED);
-	}
+	raw_spin_lock_irqsave(&task->pi_lock, flags);
+	if (READ_ONCE(task->__state) == __TASK_TRACED)
+		WRITE_ONCE(task->__state, TASK_TRACED);
+
+#ifdef CONFIG_PREEMPT_RT
+	else if (task->saved_state == __TASK_TRACED)
+		task->saved_state = TASK_TRACED;
+#endif
+	else
+		frozen = false;
+	raw_spin_unlock_irqrestore(&task->pi_lock, flags);
+
+	if (frozen && __fatal_signal_pending(task))
+		wake_up_state(task, __TASK_TRACED);
+
 	spin_unlock_irq(&task->sighand->siglock);
 }
 
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index d64f0b1d8cd3b..d3476223c2471 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -1661,7 +1661,7 @@ static void test_rcu_tasks_callback(struct rcu_head *rhp)
 	rttd->notrun = true;
 }
 
-static void rcu_tasks_initiate_self_tests(void)
+void rcu_tasks_initiate_self_tests(void)
 {
 	pr_info("Running RCU-tasks wait API self tests\n");
 #ifdef CONFIG_TASKS_RCU
@@ -1698,9 +1698,7 @@ static int rcu_tasks_verify_self_tests(void)
 	return ret;
 }
 late_initcall(rcu_tasks_verify_self_tests);
-#else /* #ifdef CONFIG_PROVE_RCU */
-static void rcu_tasks_initiate_self_tests(void) { }
-#endif /* #else #ifdef CONFIG_PROVE_RCU */
+#endif /* #ifdef CONFIG_PROVE_RCU */
 
 void __init rcu_init_tasks_generic(void)
 {
@@ -1715,9 +1713,6 @@ void __init rcu_init_tasks_generic(void)
 #ifdef CONFIG_TASKS_TRACE_RCU
 	rcu_spawn_tasks_trace_kthread();
 #endif
-
-	// Run the self-tests.
-	rcu_tasks_initiate_self_tests();
 }
 
 #else /* #ifdef CONFIG_TASKS_RCU_GENERIC */
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index 21bebf7c9030b..5da13ae5becba 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -587,6 +587,7 @@ static void print_cpu_stall(unsigned long gps)
 	 * See Documentation/RCU/stallwarn.rst for info on how to debug
 	 * RCU CPU stall warnings.
 	 */
+	printk_direct_enter();
 	trace_rcu_stall_warning(rcu_state.name, TPS("SelfDetected"));
 	pr_err("INFO: %s self-detected stall on CPU\n", rcu_state.name);
 	raw_spin_lock_irqsave_rcu_node(rdp->mynode, flags);
@@ -621,6 +622,7 @@ static void print_cpu_stall(unsigned long gps)
 	 */
 	set_tsk_need_resched(current);
 	set_preempt_need_resched();
+	printk_direct_exit();
 }
 
 static void check_cpu_stall(struct rcu_data *rdp)
diff --git a/kernel/reboot.c b/kernel/reboot.c
index 6bcc5d6a6572b..0f219ce610fce 100644
--- a/kernel/reboot.c
+++ b/kernel/reboot.c
@@ -447,9 +447,11 @@ static int __orderly_reboot(void)
 	ret = run_cmd(reboot_cmd);
 
 	if (ret) {
+		printk_direct_enter();
 		pr_warn("Failed to start orderly reboot: forcing the issue\n");
 		emergency_sync();
 		kernel_restart(NULL);
+		printk_direct_exit();
 	}
 
 	return ret;
@@ -462,6 +464,7 @@ static int __orderly_poweroff(bool force)
 	ret = run_cmd(poweroff_cmd);
 
 	if (ret && force) {
+		printk_direct_enter();
 		pr_warn("Failed to start orderly shutdown: forcing the issue\n");
 
 		/*
@@ -471,6 +474,7 @@ static int __orderly_poweroff(bool force)
 		 */
 		emergency_sync();
 		kernel_power_off();
+		printk_direct_exit();
 	}
 
 	return ret;
@@ -528,6 +532,8 @@ EXPORT_SYMBOL_GPL(orderly_reboot);
  */
 static void hw_failure_emergency_poweroff_func(struct work_struct *work)
 {
+	printk_direct_enter();
+
 	/*
 	 * We have reached here after the emergency shutdown waiting period has
 	 * expired. This means orderly_poweroff has not been able to shut off
@@ -544,6 +550,8 @@ static void hw_failure_emergency_poweroff_func(struct work_struct *work)
 	 */
 	pr_emerg("Hardware protection shutdown failed. Trying emergency restart\n");
 	emergency_restart();
+
+	printk_direct_exit();
 }
 
 static DECLARE_DELAYED_WORK(hw_failure_emergency_poweroff_work,
@@ -582,11 +590,13 @@ void hw_protection_shutdown(const char *reason, int ms_until_forced)
 {
 	static atomic_t allow_proceed = ATOMIC_INIT(1);
 
+	printk_direct_enter();
+
 	pr_emerg("HARDWARE PROTECTION shutdown (%s)\n", reason);
 
 	/* Shutdown should be initiated only once. */
 	if (!atomic_dec_and_test(&allow_proceed))
-		return;
+		goto out;
 
 	/*
 	 * Queue a backup emergency shutdown in the event of
@@ -594,6 +604,8 @@ void hw_protection_shutdown(const char *reason, int ms_until_forced)
 	 */
 	hw_failure_emergency_poweroff(ms_until_forced);
 	orderly_poweroff(true);
+out:
+	printk_direct_exit();
 }
 EXPORT_SYMBOL_GPL(hw_protection_shutdown);
 
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 848eaa0efe0ea..2ef91fb295e28 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -997,6 +997,46 @@ void resched_curr(struct rq *rq)
 		trace_sched_wake_idle_without_ipi(cpu);
 }
 
+#ifdef CONFIG_PREEMPT_LAZY
+
+static int tsk_is_polling(struct task_struct *p)
+{
+#ifdef TIF_POLLING_NRFLAG
+	return test_tsk_thread_flag(p, TIF_POLLING_NRFLAG);
+#else
+	return 0;
+#endif
+}
+
+void resched_curr_lazy(struct rq *rq)
+{
+	struct task_struct *curr = rq->curr;
+	int cpu;
+
+	if (!sched_feat(PREEMPT_LAZY)) {
+		resched_curr(rq);
+		return;
+	}
+
+	if (test_tsk_need_resched(curr))
+		return;
+
+	if (test_tsk_need_resched_lazy(curr))
+		return;
+
+	set_tsk_need_resched_lazy(curr);
+
+	cpu = cpu_of(rq);
+	if (cpu == smp_processor_id())
+		return;
+
+	/* NEED_RESCHED_LAZY must be visible before we test polling */
+	smp_mb();
+	if (!tsk_is_polling(curr))
+		smp_send_reschedule(cpu);
+}
+#endif
+
 void resched_cpu(int cpu)
 {
 	struct rq *rq = cpu_rq(cpu);
@@ -2171,6 +2211,7 @@ void migrate_disable(void)
 	preempt_disable();
 	this_rq()->nr_pinned++;
 	p->migration_disabled = 1;
+	preempt_lazy_disable();
 	preempt_enable();
 }
 EXPORT_SYMBOL_GPL(migrate_disable);
@@ -2202,6 +2243,7 @@ void migrate_enable(void)
 	barrier();
 	p->migration_disabled = 0;
 	this_rq()->nr_pinned--;
+	preempt_lazy_enable();
 	preempt_enable();
 }
 EXPORT_SYMBOL_GPL(migrate_enable);
@@ -3239,7 +3281,7 @@ unsigned long wait_task_inactive(struct task_struct *p, unsigned int match_state
 		 * is actually now running somewhere else!
 		 */
 		while (task_running(rq, p)) {
-			if (match_state && unlikely(READ_ONCE(p->__state) != match_state))
+			if (match_state && !task_match_state_lock(p, match_state))
 				return 0;
 			cpu_relax();
 		}
@@ -3254,7 +3296,7 @@ unsigned long wait_task_inactive(struct task_struct *p, unsigned int match_state
 		running = task_running(rq, p);
 		queued = task_on_rq_queued(p);
 		ncsw = 0;
-		if (!match_state || READ_ONCE(p->__state) == match_state)
+		if (!match_state || task_match_state_or_saved(p, match_state))
 			ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
 		task_rq_unlock(rq, p, &rf);
 
@@ -4432,6 +4474,9 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p)
 	p->on_cpu = 0;
 #endif
 	init_task_preempt_count(p);
+#ifdef CONFIG_HAVE_PREEMPT_LAZY
+	task_thread_info(p)->preempt_lazy_count = 0;
+#endif
 #ifdef CONFIG_SMP
 	plist_node_init(&p->pushable_tasks, MAX_PRIO);
 	RB_CLEAR_NODE(&p->pushable_dl_tasks);
@@ -4894,8 +4939,11 @@ static struct rq *finish_task_switch(struct task_struct *prev)
 		if (prev->sched_class->task_dead)
 			prev->sched_class->task_dead(prev);
 
-		/* Task is done with its stack. */
-		put_task_stack(prev);
+		/*
+		 * Cache only the VMAP stack. The final deallocation is in
+		 * delayed_put_task_struct.
+		 */
+		put_task_stack_sched(prev);
 
 		put_task_struct_rcu_user(prev);
 	}
@@ -6258,6 +6306,7 @@ static void __sched notrace __schedule(unsigned int sched_mode)
 
 	next = pick_next_task(rq, prev, &rf);
 	clear_tsk_need_resched(prev);
+	clear_tsk_need_resched_lazy(prev);
 	clear_preempt_need_resched();
 #ifdef CONFIG_SCHED_DEBUG
 	rq->last_seen_need_resched_ns = 0;
@@ -6469,6 +6518,30 @@ static void __sched notrace preempt_schedule_common(void)
 	} while (need_resched());
 }
 
+#ifdef CONFIG_PREEMPT_LAZY
+/*
+ * If TIF_NEED_RESCHED is then we allow to be scheduled away since this is
+ * set by a RT task. Oterwise we try to avoid beeing scheduled out as long as
+ * preempt_lazy_count counter >0.
+ */
+static __always_inline int preemptible_lazy(void)
+{
+	if (test_thread_flag(TIF_NEED_RESCHED))
+		return 1;
+	if (current_thread_info()->preempt_lazy_count)
+		return 0;
+	return 1;
+}
+
+#else
+
+static inline int preemptible_lazy(void)
+{
+	return 1;
+}
+
+#endif
+
 #ifdef CONFIG_PREEMPTION
 /*
  * This is the entry point to schedule() from in-kernel preemption
@@ -6482,7 +6555,8 @@ asmlinkage __visible void __sched notrace preempt_schedule(void)
 	 */
 	if (likely(!preemptible()))
 		return;
-
+	if (!preemptible_lazy())
+		return;
 	preempt_schedule_common();
 }
 NOKPROBE_SYMBOL(preempt_schedule);
@@ -6515,6 +6589,9 @@ asmlinkage __visible void __sched notrace preempt_schedule_notrace(void)
 	if (likely(!preemptible()))
 		return;
 
+	if (!preemptible_lazy())
+		return;
+
 	do {
 		/*
 		 * Because the function tracer can trace preempt_count_sub()
@@ -8681,7 +8758,9 @@ void __init init_idle(struct task_struct *idle, int cpu)
 
 	/* Set the preempt count _outside_ the spinlocks! */
 	init_idle_preempt_count(idle, cpu);
-
+#ifdef CONFIG_HAVE_PREEMPT_LAZY
+	task_thread_info(idle)->preempt_lazy_count = 0;
+#endif
 	/*
 	 * The idle tasks have their own, simple scheduling class:
 	 */
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 5146163bfabb9..206c1e03e2d11 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4427,7 +4427,7 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
 	ideal_runtime = sched_slice(cfs_rq, curr);
 	delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
 	if (delta_exec > ideal_runtime) {
-		resched_curr(rq_of(cfs_rq));
+		resched_curr_lazy(rq_of(cfs_rq));
 		/*
 		 * The current task ran long enough, ensure it doesn't get
 		 * re-elected due to buddy favours.
@@ -4451,7 +4451,7 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
 		return;
 
 	if (delta > ideal_runtime)
-		resched_curr(rq_of(cfs_rq));
+		resched_curr_lazy(rq_of(cfs_rq));
 }
 
 static void
@@ -4597,7 +4597,7 @@ entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
 	 * validating it and just reschedule.
 	 */
 	if (queued) {
-		resched_curr(rq_of(cfs_rq));
+		resched_curr_lazy(rq_of(cfs_rq));
 		return;
 	}
 	/*
@@ -4746,7 +4746,7 @@ static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec)
 	 * hierarchy can be throttled
 	 */
 	if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr))
-		resched_curr(rq_of(cfs_rq));
+		resched_curr_lazy(rq_of(cfs_rq));
 }
 
 static __always_inline
@@ -5509,7 +5509,7 @@ static void hrtick_start_fair(struct rq *rq, struct task_struct *p)
 
 		if (delta < 0) {
 			if (task_current(rq, p))
-				resched_curr(rq);
+				resched_curr_lazy(rq);
 			return;
 		}
 		hrtick_start(rq, delta);
@@ -7159,7 +7159,7 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_
 	return;
 
 preempt:
-	resched_curr(rq);
+	resched_curr_lazy(rq);
 	/*
 	 * Only set the backward buddy when the current task is still
 	 * on the rq. This can happen when a wakeup gets interleaved
@@ -11196,7 +11196,7 @@ static void task_fork_fair(struct task_struct *p)
 		 * 'current' within the tree based on its new key value.
 		 */
 		swap(curr->vruntime, se->vruntime);
-		resched_curr(rq);
+		resched_curr_lazy(rq);
 	}
 
 	se->vruntime -= cfs_rq->min_vruntime;
@@ -11223,7 +11223,7 @@ prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio)
 	 */
 	if (task_current(rq, p)) {
 		if (p->prio > oldprio)
-			resched_curr(rq);
+			resched_curr_lazy(rq);
 	} else
 		check_preempt_curr(rq, p, 0);
 }
diff --git a/kernel/sched/features.h b/kernel/sched/features.h
index 1cf435bbcd9ca..d5cee51819bf7 100644
--- a/kernel/sched/features.h
+++ b/kernel/sched/features.h
@@ -48,6 +48,9 @@ SCHED_FEAT(NONTASK_CAPACITY, true)
 
 #ifdef CONFIG_PREEMPT_RT
 SCHED_FEAT(TTWU_QUEUE, false)
+# ifdef CONFIG_PREEMPT_LAZY
+SCHED_FEAT(PREEMPT_LAZY, true)
+# endif
 #else
 
 /*
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index de53be9057390..05430e268fdd3 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2328,6 +2328,15 @@ extern void reweight_task(struct task_struct *p, int prio);
 extern void resched_curr(struct rq *rq);
 extern void resched_cpu(int cpu);
 
+#ifdef CONFIG_PREEMPT_LAZY
+extern void resched_curr_lazy(struct rq *rq);
+#else
+static inline void resched_curr_lazy(struct rq *rq)
+{
+	resched_curr(rq);
+}
+#endif
+
 extern struct rt_bandwidth def_rt_bandwidth;
 extern void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime);
 
diff --git a/kernel/sched/swait.c b/kernel/sched/swait.c
index e1c655f928c74..f230b1ac7f910 100644
--- a/kernel/sched/swait.c
+++ b/kernel/sched/swait.c
@@ -64,6 +64,7 @@ void swake_up_all(struct swait_queue_head *q)
 	struct swait_queue *curr;
 	LIST_HEAD(tmp);
 
+	WARN_ON(irqs_disabled());
 	raw_spin_lock_irq(&q->lock);
 	list_splice_init(&q->task_list, &tmp);
 	while (!list_empty(&tmp)) {
diff --git a/kernel/signal.c b/kernel/signal.c
index 38602738866e3..68048110c0be4 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1327,6 +1327,34 @@ force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t,
 	struct k_sigaction *action;
 	int sig = info->si_signo;
 
+	/*
+	 * On some archs, PREEMPT_RT has to delay sending a signal from a trap
+	 * since it can not enable preemption, and the signal code's spin_locks
+	 * turn into mutexes. Instead, it must set TIF_NOTIFY_RESUME which will
+	 * send the signal on exit of the trap.
+	 */
+#ifdef ARCH_RT_DELAYS_SIGNAL_SEND
+	if (in_atomic()) {
+		struct task_struct *t = current;
+
+		if (WARN_ON_ONCE(t->forced_info.si_signo))
+			return 0;
+
+		if (is_si_special(info)) {
+			WARN_ON_ONCE(info != SEND_SIG_PRIV);
+			t->forced_info.si_signo = info->si_signo;
+			t->forced_info.si_errno = 0;
+			t->forced_info.si_code = SI_KERNEL;
+			t->forced_info.si_pid = 0;
+			t->forced_info.si_uid = 0;
+		} else {
+			t->forced_info = *info;
+		}
+
+		set_tsk_thread_flag(t, TIF_NOTIFY_RESUME);
+		return 0;
+	}
+#endif
 	spin_lock_irqsave(&t->sighand->siglock, flags);
 	action = &t->sighand->action[sig-1];
 	ignored = action->sa.sa_handler == SIG_IGN;
@@ -2275,16 +2303,8 @@ static void ptrace_stop(int exit_code, int why, int clear_code, kernel_siginfo_t
 		if (gstop_done && ptrace_reparented(current))
 			do_notify_parent_cldstop(current, false, why);
 
-		/*
-		 * Don't want to allow preemption here, because
-		 * sys_ptrace() needs this task to be inactive.
-		 *
-		 * XXX: implement read_unlock_no_resched().
-		 */
-		preempt_disable();
 		read_unlock(&tasklist_lock);
 		cgroup_enter_frozen();
-		preempt_enable_no_resched();
 		freezable_schedule();
 		cgroup_leave_frozen(true);
 	} else {
diff --git a/kernel/smp.c b/kernel/smp.c
index 01a7c1706a58b..250311c2009fe 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -690,10 +690,20 @@ void flush_smp_call_function_from_idle(void)
 
 	cfd_seq_store(this_cpu_ptr(&cfd_seq_local)->idle, CFD_SEQ_NOCPU,
 		      smp_processor_id(), CFD_SEQ_IDLE);
+
 	local_irq_save(flags);
 	flush_smp_call_function_queue(true);
-	if (local_softirq_pending())
-		do_softirq();
+
+	if (local_softirq_pending()) {
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT)) {
+			do_softirq();
+		} else {
+			struct task_struct *ksoftirqd = this_cpu_ksoftirqd();
+
+			if (ksoftirqd && !task_is_running(ksoftirqd))
+				wake_up_process(ksoftirqd);
+		}
+	}
 
 	local_irq_restore(flags);
 }
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 41f470929e991..22948c2109f5b 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -624,6 +624,22 @@ static inline void tick_irq_exit(void)
 #endif
 }
 
+static DEFINE_PER_CPU(struct task_struct *, timersd);
+static DEFINE_PER_CPU(unsigned long, pending_timer_softirq);
+
+static unsigned int local_pending_timers(void)
+{
+        return __this_cpu_read(pending_timer_softirq);
+}
+
+static void wake_timersd(void)
+{
+        struct task_struct *tsk = __this_cpu_read(timersd);
+
+        if (tsk)
+                wake_up_process(tsk);
+}
+
 static inline void __irq_exit_rcu(void)
 {
 #ifndef __ARCH_IRQ_EXIT_IRQS_DISABLED
@@ -635,6 +651,8 @@ static inline void __irq_exit_rcu(void)
 	preempt_count_sub(HARDIRQ_OFFSET);
 	if (!in_interrupt() && local_softirq_pending())
 		invoke_softirq();
+	if (IS_ENABLED(CONFIG_PREEMPT_RT) && !in_interrupt() && local_pending_timers())
+		wake_timersd();
 
 	tick_irq_exit();
 }
@@ -963,11 +981,69 @@ static struct smp_hotplug_thread softirq_threads = {
 	.thread_comm		= "ksoftirqd/%u",
 };
 
+static void timersd_setup(unsigned int cpu)
+{
+        sched_set_fifo_low(current);
+}
+
+static int timersd_should_run(unsigned int cpu)
+{
+        return local_pending_timers();
+}
+
+static void run_timersd(unsigned int cpu)
+{
+	unsigned int timer_si;
+
+	ksoftirqd_run_begin();
+
+	timer_si = local_pending_timers();
+	__this_cpu_write(pending_timer_softirq, 0);
+	or_softirq_pending(timer_si);
+
+	__do_softirq();
+
+	ksoftirqd_run_end();
+}
+
+#ifdef CONFIG_PREEMPT_RT
+static void raise_ktimers_thread(unsigned int nr)
+{
+	trace_softirq_raise(nr);
+	__this_cpu_or(pending_timer_softirq, 1 << nr);
+}
+
+void raise_hrtimer_softirq(void)
+{
+	raise_ktimers_thread(HRTIMER_SOFTIRQ);
+}
+
+void raise_timer_softirq(void)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	raise_ktimers_thread(TIMER_SOFTIRQ);
+	wake_timersd();
+	local_irq_restore(flags);
+}
+#endif
+
+static struct smp_hotplug_thread timer_threads = {
+        .store                  = &timersd,
+        .setup                  = timersd_setup,
+        .thread_should_run      = timersd_should_run,
+        .thread_fn              = run_timersd,
+        .thread_comm            = "ktimers/%u",
+};
+
 static __init int spawn_ksoftirqd(void)
 {
 	cpuhp_setup_state_nocalls(CPUHP_SOFTIRQ_DEAD, "softirq:dead", NULL,
 				  takeover_tasklets);
 	BUG_ON(smpboot_register_percpu_thread(&softirq_threads));
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		BUG_ON(smpboot_register_percpu_thread(&timer_threads));
 
 	return 0;
 }
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 0ea8702eb5163..dead5e738ecf1 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1805,7 +1805,7 @@ void hrtimer_interrupt(struct clock_event_device *dev)
 	if (!ktime_before(now, cpu_base->softirq_expires_next)) {
 		cpu_base->softirq_expires_next = KTIME_MAX;
 		cpu_base->softirq_activated = 1;
-		raise_softirq_irqoff(HRTIMER_SOFTIRQ);
+		raise_hrtimer_softirq();
 	}
 
 	__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
@@ -1918,7 +1918,7 @@ void hrtimer_run_queues(void)
 	if (!ktime_before(now, cpu_base->softirq_expires_next)) {
 		cpu_base->softirq_expires_next = KTIME_MAX;
 		cpu_base->softirq_activated = 1;
-		raise_softirq_irqoff(HRTIMER_SOFTIRQ);
+		raise_hrtimer_softirq();
 	}
 
 	__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 85f1021ad4595..beb4b1cc7c48c 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1766,7 +1766,7 @@ static void run_local_timers(void)
 		if (time_before(jiffies, base->next_expiry))
 			return;
 	}
-	raise_softirq(TIMER_SOFTIRQ);
+	raise_timer_softirq();
 }
 
 /*
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c860f582b0788..aaab9844b3139 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2606,11 +2606,19 @@ unsigned int tracing_gen_ctx_irq_test(unsigned int irqs_status)
 	if (softirq_count() >> (SOFTIRQ_SHIFT + 1))
 		trace_flags |= TRACE_FLAG_BH_OFF;
 
-	if (tif_need_resched())
+	if (tif_need_resched_now())
 		trace_flags |= TRACE_FLAG_NEED_RESCHED;
+#ifdef CONFIG_PREEMPT_LAZY
+	/* Run out of bits. Share the LAZY and PREEMPT_RESCHED */
+	if (need_resched_lazy())
+		trace_flags |= TRACE_FLAG_NEED_RESCHED_LAZY;
+#else
 	if (test_preempt_need_resched())
 		trace_flags |= TRACE_FLAG_PREEMPT_RESCHED;
-	return (trace_flags << 16) | (min_t(unsigned int, pc & 0xff, 0xf)) |
+#endif
+
+	return (trace_flags << 24) | (min_t(unsigned int, pc & 0xff, 0xf)) |
+		(preempt_lazy_count() & 0xff) << 16 |
 		(min_t(unsigned int, migration_disable_value(), 0xf)) << 4;
 }
 
@@ -4191,15 +4199,17 @@ unsigned long trace_total_entries(struct trace_array *tr)
 
 static void print_lat_help_header(struct seq_file *m)
 {
-	seq_puts(m, "#                    _------=> CPU#            \n"
-		    "#                   / _-----=> irqs-off/BH-disabled\n"
-		    "#                  | / _----=> need-resched    \n"
-		    "#                  || / _---=> hardirq/softirq \n"
-		    "#                  ||| / _--=> preempt-depth   \n"
-		    "#                  |||| / _-=> migrate-disable \n"
-		    "#                  ||||| /     delay           \n"
-		    "#  cmd     pid     |||||| time  |   caller     \n"
-		    "#     \\   /        ||||||  \\    |    /       \n");
+	seq_puts(m, "#                    _--------=> CPU#            \n"
+		    "#                   / _-------=> irqs-off/BH-disabled\n"
+		    "#                  | / _------=> need-resched    \n"
+		    "#                  || / _-----=> need-resched-lazy\n"
+		    "#                  ||| / _----=> hardirq/softirq \n"
+		    "#                  |||| / _---=> preempt-depth   \n"
+		    "#                  ||||| / _--=> preempt-lazy-depth\n"
+		    "#                  |||||| / _-=> migrate-disable \n"
+		    "#                  ||||||| /     delay           \n"
+		    "#  cmd     pid     |||||||| time  |   caller     \n"
+		    "#     \\   /        ||||||||  \\    |    /       \n");
 }
 
 static void print_event_info(struct array_buffer *buf, struct seq_file *m)
@@ -4233,14 +4243,16 @@ static void print_func_help_header_irq(struct array_buffer *buf, struct seq_file
 
 	print_event_info(buf, m);
 
-	seq_printf(m, "#                            %.*s  _-----=> irqs-off/BH-disabled\n", prec, space);
-	seq_printf(m, "#                            %.*s / _----=> need-resched\n", prec, space);
-	seq_printf(m, "#                            %.*s| / _---=> hardirq/softirq\n", prec, space);
-	seq_printf(m, "#                            %.*s|| / _--=> preempt-depth\n", prec, space);
-	seq_printf(m, "#                            %.*s||| / _-=> migrate-disable\n", prec, space);
-	seq_printf(m, "#                            %.*s|||| /     delay\n", prec, space);
-	seq_printf(m, "#           TASK-PID  %.*s CPU#  |||||  TIMESTAMP  FUNCTION\n", prec, "     TGID   ");
-	seq_printf(m, "#              | |    %.*s   |   |||||     |         |\n", prec, "       |    ");
+	seq_printf(m, "#                            %.*s  _-------=> irqs-off/BH-disabled\n", prec, space);
+	seq_printf(m, "#                            %.*s / _------=> need-resched\n", prec, space);
+	seq_printf(m, "#                            %.*s| / _-----=> need-resched-lazy\n", prec, space);
+	seq_printf(m, "#                            %.*s|| / _----=> hardirq/softirq\n", prec, space);
+	seq_printf(m, "#                            %.*s||| / _---=> preempt-depth\n", prec, space);
+	seq_printf(m, "#                            %.*s|||| / _--=> preempt-lazy-depth\n", prec, space);
+	seq_printf(m, "#                            %.*s||||| / _-=> migrate-disable\n", prec, space);
+	seq_printf(m, "#                            %.*s|||||| /     delay\n", prec, space);
+	seq_printf(m, "#           TASK-PID  %.*s CPU#  |||||||  TIMESTAMP  FUNCTION\n", prec, "     TGID   ");
+	seq_printf(m, "#              | |    %.*s   |   |||||||      |         |\n", prec, "       |    ");
 }
 
 void
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 3147614c1812a..13695a8c36647 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -184,6 +184,7 @@ static int trace_define_common_fields(void)
 	/* Holds both preempt_count and migrate_disable */
 	__common_field(unsigned char, preempt_count);
 	__common_field(int, pid);
+	__common_field(unsigned char, preempt_lazy_count);
 
 	return ret;
 }
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index 8aa493d25c73e..747d1ca5215e4 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -442,6 +442,7 @@ int trace_print_lat_fmt(struct trace_seq *s, struct trace_entry *entry)
 {
 	char hardsoft_irq;
 	char need_resched;
+	char need_resched_lazy;
 	char irqs_off;
 	int hardirq;
 	int softirq;
@@ -462,20 +463,27 @@ int trace_print_lat_fmt(struct trace_seq *s, struct trace_entry *entry)
 
 	switch (entry->flags & (TRACE_FLAG_NEED_RESCHED |
 				TRACE_FLAG_PREEMPT_RESCHED)) {
+#ifndef CONFIG_PREEMPT_LAZY
 	case TRACE_FLAG_NEED_RESCHED | TRACE_FLAG_PREEMPT_RESCHED:
 		need_resched = 'N';
 		break;
+#endif
 	case TRACE_FLAG_NEED_RESCHED:
 		need_resched = 'n';
 		break;
+#ifndef CONFIG_PREEMPT_LAZY
 	case TRACE_FLAG_PREEMPT_RESCHED:
 		need_resched = 'p';
 		break;
+#endif
 	default:
 		need_resched = '.';
 		break;
 	}
 
+	need_resched_lazy =
+		(entry->flags & TRACE_FLAG_NEED_RESCHED_LAZY) ? 'L' : '.';
+
 	hardsoft_irq =
 		(nmi && hardirq)     ? 'Z' :
 		nmi                  ? 'z' :
@@ -484,14 +492,20 @@ int trace_print_lat_fmt(struct trace_seq *s, struct trace_entry *entry)
 		softirq              ? 's' :
 		                       '.' ;
 
-	trace_seq_printf(s, "%c%c%c",
-			 irqs_off, need_resched, hardsoft_irq);
+	trace_seq_printf(s, "%c%c%c%c",
+			 irqs_off, need_resched, need_resched_lazy,
+			 hardsoft_irq);
 
 	if (entry->preempt_count & 0xf)
 		trace_seq_printf(s, "%x", entry->preempt_count & 0xf);
 	else
 		trace_seq_putc(s, '.');
 
+	if (entry->preempt_lazy_count)
+		trace_seq_printf(s, "%x", entry->preempt_lazy_count);
+	else
+		trace_seq_putc(s, '.');
+
 	if (entry->preempt_count & 0xf0)
 		trace_seq_printf(s, "%x", entry->preempt_count >> 4);
 	else
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 99afb88d2e85a..583a53b3928c5 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -424,6 +424,8 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
 		/* Start period for the next softlockup warning. */
 		update_report_ts();
 
+		printk_direct_enter();
+
 		pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n",
 			smp_processor_id(), duration,
 			current->comm, task_pid_nr(current));
@@ -442,6 +444,8 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
 		add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK);
 		if (softlockup_panic)
 			panic("softlockup: hung tasks");
+
+		printk_direct_exit();
 	}
 
 	return HRTIMER_RESTART;
diff --git a/kernel/watchdog_hld.c b/kernel/watchdog_hld.c
index 247bf0b1582ca..56cfbae94c423 100644
--- a/kernel/watchdog_hld.c
+++ b/kernel/watchdog_hld.c
@@ -135,6 +135,8 @@ static void watchdog_overflow_callback(struct perf_event *event,
 		if (__this_cpu_read(hard_watchdog_warn) == true)
 			return;
 
+		printk_direct_enter();
+
 		pr_emerg("Watchdog detected hard LOCKUP on cpu %d\n",
 			 this_cpu);
 		print_modules();
@@ -155,6 +157,8 @@ static void watchdog_overflow_callback(struct perf_event *event,
 		if (hardlockup_panic)
 			nmi_panic(regs, "Hard LOCKUP");
 
+		printk_direct_exit();
+
 		__this_cpu_write(hard_watchdog_warn, true);
 		return;
 	}
diff --git a/lib/dump_stack.c b/lib/dump_stack.c
index 6b7f1bf6715d8..e3b4eeb1dcb45 100644
--- a/lib/dump_stack.c
+++ b/lib/dump_stack.c
@@ -102,9 +102,11 @@ asmlinkage __visible void dump_stack_lvl(const char *log_lvl)
 	 * Permit this cpu to perform nested stack dumps while serialising
 	 * against other CPUs
 	 */
-	printk_cpu_lock_irqsave(flags);
+	printk_direct_enter();
+	printk_cpu_sync_get_irqsave(flags);
 	__dump_stack(log_lvl);
-	printk_cpu_unlock_irqrestore(flags);
+	printk_cpu_sync_put_irqrestore(flags);
+	printk_direct_exit();
 }
 EXPORT_SYMBOL(dump_stack_lvl);
 
diff --git a/lib/irq_poll.c b/lib/irq_poll.c
index 2f17b488d58e1..2b9f797642f60 100644
--- a/lib/irq_poll.c
+++ b/lib/irq_poll.c
@@ -191,11 +191,13 @@ static int irq_poll_cpu_dead(unsigned int cpu)
 	 * If a CPU goes away, splice its entries to the current CPU
 	 * and trigger a run of the softirq
 	 */
+	local_bh_disable();
 	local_irq_disable();
 	list_splice_init(&per_cpu(blk_cpu_iopoll, cpu),
 			 this_cpu_ptr(&blk_cpu_iopoll));
 	__raise_softirq_irqoff(IRQ_POLL_SOFTIRQ);
 	local_irq_enable();
+	local_bh_enable();
 
 	return 0;
 }
diff --git a/lib/nmi_backtrace.c b/lib/nmi_backtrace.c
index 199ab201d5019..dabeb35bc8dc7 100644
--- a/lib/nmi_backtrace.c
+++ b/lib/nmi_backtrace.c
@@ -99,7 +99,8 @@ bool nmi_cpu_backtrace(struct pt_regs *regs)
 		 * Allow nested NMI backtraces while serializing
 		 * against other CPUs.
 		 */
-		printk_cpu_lock_irqsave(flags);
+		printk_direct_enter();
+		printk_cpu_sync_get_irqsave(flags);
 		if (!READ_ONCE(backtrace_idle) && regs && cpu_in_idle(instruction_pointer(regs))) {
 			pr_warn("NMI backtrace for cpu %d skipped: idling at %pS\n",
 				cpu, (void *)instruction_pointer(regs));
@@ -110,7 +111,8 @@ bool nmi_cpu_backtrace(struct pt_regs *regs)
 			else
 				dump_stack();
 		}
-		printk_cpu_unlock_irqrestore(flags);
+		printk_cpu_sync_put_irqrestore(flags);
+		printk_direct_exit();
 		cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
 		return true;
 	}
diff --git a/localversion-rt b/localversion-rt
new file mode 100644
index 0000000000000..ad3da1bcab7e8
--- /dev/null
+++ b/localversion-rt
@@ -0,0 +1 @@
+-rt4
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 09d342c7cbd0d..20ea8f28ad99b 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -169,7 +169,6 @@ struct mem_cgroup_event {
 	struct work_struct remove;
 };
 
-static void mem_cgroup_threshold(struct mem_cgroup *memcg);
 static void mem_cgroup_oom_notify(struct mem_cgroup *memcg);
 
 /* Stuffs for move charges at task migration. */
@@ -261,8 +260,10 @@ bool mem_cgroup_kmem_disabled(void)
 	return cgroup_memory_nokmem;
 }
 
+struct memcg_stock_pcp;
 static void obj_cgroup_uncharge_pages(struct obj_cgroup *objcg,
-				      unsigned int nr_pages);
+				      unsigned int nr_pages,
+				      bool stock_lock_acquried);
 
 static void obj_cgroup_release(struct percpu_ref *ref)
 {
@@ -296,7 +297,7 @@ static void obj_cgroup_release(struct percpu_ref *ref)
 	nr_pages = nr_bytes >> PAGE_SHIFT;
 
 	if (nr_pages)
-		obj_cgroup_uncharge_pages(objcg, nr_pages);
+		obj_cgroup_uncharge_pages(objcg, nr_pages, false);
 
 	spin_lock_irqsave(&css_set_lock, flags);
 	list_del(&objcg->list);
@@ -521,43 +522,6 @@ static unsigned long soft_limit_excess(struct mem_cgroup *memcg)
 	return excess;
 }
 
-static void mem_cgroup_update_tree(struct mem_cgroup *memcg, int nid)
-{
-	unsigned long excess;
-	struct mem_cgroup_per_node *mz;
-	struct mem_cgroup_tree_per_node *mctz;
-
-	mctz = soft_limit_tree.rb_tree_per_node[nid];
-	if (!mctz)
-		return;
-	/*
-	 * Necessary to update all ancestors when hierarchy is used.
-	 * because their event counter is not touched.
-	 */
-	for (; memcg; memcg = parent_mem_cgroup(memcg)) {
-		mz = memcg->nodeinfo[nid];
-		excess = soft_limit_excess(memcg);
-		/*
-		 * We have to update the tree if mz is on RB-tree or
-		 * mem is over its softlimit.
-		 */
-		if (excess || mz->on_tree) {
-			unsigned long flags;
-
-			spin_lock_irqsave(&mctz->lock, flags);
-			/* if on-tree, remove it */
-			if (mz->on_tree)
-				__mem_cgroup_remove_exceeded(mz, mctz);
-			/*
-			 * Insert again. mz->usage_in_excess will be updated.
-			 * If excess is 0, no tree ops.
-			 */
-			__mem_cgroup_insert_exceeded(mz, mctz, excess);
-			spin_unlock_irqrestore(&mctz->lock, flags);
-		}
-	}
-}
-
 static void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg)
 {
 	struct mem_cgroup_tree_per_node *mctz;
@@ -705,6 +669,8 @@ void __mod_memcg_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
 	pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
 	memcg = pn->memcg;
 
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		preempt_disable();
 	/* Update memcg */
 	__this_cpu_add(memcg->vmstats_percpu->state[idx], val);
 
@@ -712,6 +678,8 @@ void __mod_memcg_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
 	__this_cpu_add(pn->lruvec_stats_percpu->state[idx], val);
 
 	memcg_rstat_updated(memcg, val);
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		preempt_enable();
 }
 
 /**
@@ -794,8 +762,12 @@ void __count_memcg_events(struct mem_cgroup *memcg, enum vm_event_item idx,
 	if (mem_cgroup_disabled())
 		return;
 
+	if (IS_ENABLED(PREEMPT_RT))
+		preempt_disable();
 	__this_cpu_add(memcg->vmstats_percpu->events[idx], count);
 	memcg_rstat_updated(memcg, count);
+	if (IS_ENABLED(PREEMPT_RT))
+		preempt_enable();
 }
 
 static unsigned long memcg_events(struct mem_cgroup *memcg, int event)
@@ -827,50 +799,6 @@ static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg,
 	__this_cpu_add(memcg->vmstats_percpu->nr_page_events, nr_pages);
 }
 
-static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
-				       enum mem_cgroup_events_target target)
-{
-	unsigned long val, next;
-
-	val = __this_cpu_read(memcg->vmstats_percpu->nr_page_events);
-	next = __this_cpu_read(memcg->vmstats_percpu->targets[target]);
-	/* from time_after() in jiffies.h */
-	if ((long)(next - val) < 0) {
-		switch (target) {
-		case MEM_CGROUP_TARGET_THRESH:
-			next = val + THRESHOLDS_EVENTS_TARGET;
-			break;
-		case MEM_CGROUP_TARGET_SOFTLIMIT:
-			next = val + SOFTLIMIT_EVENTS_TARGET;
-			break;
-		default:
-			break;
-		}
-		__this_cpu_write(memcg->vmstats_percpu->targets[target], next);
-		return true;
-	}
-	return false;
-}
-
-/*
- * Check events in order.
- *
- */
-static void memcg_check_events(struct mem_cgroup *memcg, int nid)
-{
-	/* threshold event is triggered in finer grain than soft limit */
-	if (unlikely(mem_cgroup_event_ratelimit(memcg,
-						MEM_CGROUP_TARGET_THRESH))) {
-		bool do_softlimit;
-
-		do_softlimit = mem_cgroup_event_ratelimit(memcg,
-						MEM_CGROUP_TARGET_SOFTLIMIT);
-		mem_cgroup_threshold(memcg);
-		if (unlikely(do_softlimit))
-			mem_cgroup_update_tree(memcg, nid);
-	}
-}
-
 struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
 {
 	/*
@@ -2098,26 +2026,40 @@ struct obj_stock {
 };
 
 struct memcg_stock_pcp {
+	/* Protects memcg_stock_pcp */
+	local_lock_t stock_lock;
 	struct mem_cgroup *cached; /* this never be root cgroup */
 	unsigned int nr_pages;
+#ifndef CONFIG_PREEMPTION
+	/* Protects only task_obj */
+	local_lock_t task_obj_lock;
 	struct obj_stock task_obj;
+#endif
 	struct obj_stock irq_obj;
 
 	struct work_struct work;
 	unsigned long flags;
 #define FLUSHING_CACHED_CHARGE	0
 };
-static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock);
+static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock) = {
+	.stock_lock = INIT_LOCAL_LOCK(stock_lock),
+#ifndef CONFIG_PREEMPTION
+	.task_obj_lock = INIT_LOCAL_LOCK(task_obj_lock),
+#endif
+};
 static DEFINE_MUTEX(percpu_charge_mutex);
 
 #ifdef CONFIG_MEMCG_KMEM
-static void drain_obj_stock(struct obj_stock *stock);
+static struct obj_cgroup *drain_obj_stock(struct obj_stock *stock,
+					  bool stock_lock_acquried);
 static bool obj_stock_flush_required(struct memcg_stock_pcp *stock,
 				     struct mem_cgroup *root_memcg);
 
 #else
-static inline void drain_obj_stock(struct obj_stock *stock)
+static inline struct obj_cgroup *drain_obj_stock(struct obj_stock *stock,
+						 bool stock_lock_acquried)
 {
+	return NULL;
 }
 static bool obj_stock_flush_required(struct memcg_stock_pcp *stock,
 				     struct mem_cgroup *root_memcg)
@@ -2146,7 +2088,7 @@ static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
 	if (nr_pages > MEMCG_CHARGE_BATCH)
 		return ret;
 
-	local_irq_save(flags);
+	local_lock_irqsave(&memcg_stock.stock_lock, flags);
 
 	stock = this_cpu_ptr(&memcg_stock);
 	if (memcg == stock->cached && stock->nr_pages >= nr_pages) {
@@ -2154,7 +2096,7 @@ static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
 		ret = true;
 	}
 
-	local_irq_restore(flags);
+	local_unlock_irqrestore(&memcg_stock.stock_lock, flags);
 
 	return ret;
 }
@@ -2182,38 +2124,43 @@ static void drain_stock(struct memcg_stock_pcp *stock)
 
 static void drain_local_stock(struct work_struct *dummy)
 {
-	struct memcg_stock_pcp *stock;
-	unsigned long flags;
+	struct memcg_stock_pcp *stock_pcp;
+	struct obj_cgroup *old;
 
 	/*
 	 * The only protection from cpu hotplug (memcg_hotplug_cpu_dead) vs.
 	 * drain_stock races is that we always operate on local CPU stock
 	 * here with IRQ disabled
 	 */
-	local_irq_save(flags);
+#ifndef CONFIG_PREEMPTION
+	local_lock(&memcg_stock.task_obj_lock);
+	old = drain_obj_stock(&this_cpu_ptr(&memcg_stock)->task_obj, NULL);
+	local_unlock(&memcg_stock.task_obj_lock);
+	if (old)
+		obj_cgroup_put(old);
+#endif
 
-	stock = this_cpu_ptr(&memcg_stock);
-	drain_obj_stock(&stock->irq_obj);
-	if (in_task())
-		drain_obj_stock(&stock->task_obj);
-	drain_stock(stock);
-	clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags);
+	local_lock_irq(&memcg_stock.stock_lock);
+	stock_pcp = this_cpu_ptr(&memcg_stock);
+	old = drain_obj_stock(&stock_pcp->irq_obj, stock_pcp);
 
-	local_irq_restore(flags);
+	drain_stock(stock_pcp);
+	clear_bit(FLUSHING_CACHED_CHARGE, &stock_pcp->flags);
+
+	local_unlock_irq(&memcg_stock.stock_lock);
+	if (old)
+		obj_cgroup_put(old);
 }
 
 /*
  * Cache charges(val) to local per_cpu area.
  * This will be consumed by consume_stock() function, later.
  */
-static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
+static void __refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
 {
-	struct memcg_stock_pcp *stock;
-	unsigned long flags;
+	struct memcg_stock_pcp *stock = this_cpu_ptr(&memcg_stock);
 
-	local_irq_save(flags);
-
-	stock = this_cpu_ptr(&memcg_stock);
+	lockdep_assert_held(&stock->stock_lock);
 	if (stock->cached != memcg) { /* reset if necessary */
 		drain_stock(stock);
 		css_get(&memcg->css);
@@ -2223,8 +2170,20 @@ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
 
 	if (stock->nr_pages > MEMCG_CHARGE_BATCH)
 		drain_stock(stock);
+}
 
-	local_irq_restore(flags);
+static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages,
+			 bool stock_lock_acquried)
+{
+	unsigned long flags;
+
+	if (stock_lock_acquried) {
+		__refill_stock(memcg, nr_pages);
+		return;
+	}
+	local_lock_irqsave(&memcg_stock.stock_lock, flags);
+	__refill_stock(memcg, nr_pages);
+	local_unlock_irqrestore(&memcg_stock.stock_lock, flags);
 }
 
 /*
@@ -2233,7 +2192,7 @@ static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
  */
 static void drain_all_stock(struct mem_cgroup *root_memcg)
 {
-	int cpu, curcpu;
+	int cpu;
 
 	/* If someone's already draining, avoid adding running more workers. */
 	if (!mutex_trylock(&percpu_charge_mutex))
@@ -2244,7 +2203,7 @@ static void drain_all_stock(struct mem_cgroup *root_memcg)
 	 * as well as workers from this path always operate on the local
 	 * per-cpu data. CPU up doesn't touch memcg_stock at all.
 	 */
-	curcpu = get_cpu();
+	cpus_read_lock();
 	for_each_online_cpu(cpu) {
 		struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
 		struct mem_cgroup *memcg;
@@ -2260,14 +2219,10 @@ static void drain_all_stock(struct mem_cgroup *root_memcg)
 		rcu_read_unlock();
 
 		if (flush &&
-		    !test_and_set_bit(FLUSHING_CACHED_CHARGE, &stock->flags)) {
-			if (cpu == curcpu)
-				drain_local_stock(&stock->work);
-			else
-				schedule_work_on(cpu, &stock->work);
-		}
+		    !test_and_set_bit(FLUSHING_CACHED_CHARGE, &stock->flags))
+			schedule_work_on(cpu, &stock->work);
 	}
-	put_cpu();
+	cpus_read_unlock();
 	mutex_unlock(&percpu_charge_mutex);
 }
 
@@ -2668,7 +2623,7 @@ static int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask,
 
 done_restock:
 	if (batch > nr_pages)
-		refill_stock(memcg, batch - nr_pages);
+		refill_stock(memcg, batch - nr_pages, false);
 
 	/*
 	 * If the hierarchy is above the normal consumption range, schedule
@@ -2781,28 +2736,36 @@ static struct mem_cgroup *get_mem_cgroup_from_objcg(struct obj_cgroup *objcg)
  * can only be accessed after disabling interrupt. User context code can
  * access interrupt object stock, but not vice versa.
  */
-static inline struct obj_stock *get_obj_stock(unsigned long *pflags)
+static inline struct obj_stock *get_obj_stock(unsigned long *pflags,
+					      bool *stock_lock_acquried)
 {
 	struct memcg_stock_pcp *stock;
 
+#ifndef CONFIG_PREEMPTION
 	if (likely(in_task())) {
 		*pflags = 0UL;
-		preempt_disable();
+		*stock_lock_acquried = false;
+		local_lock(&memcg_stock.task_obj_lock);
 		stock = this_cpu_ptr(&memcg_stock);
 		return &stock->task_obj;
 	}
-
-	local_irq_save(*pflags);
+#endif
+	*stock_lock_acquried = true;
+	local_lock_irqsave(&memcg_stock.stock_lock, *pflags);
 	stock = this_cpu_ptr(&memcg_stock);
 	return &stock->irq_obj;
 }
 
-static inline void put_obj_stock(unsigned long flags)
+static inline void put_obj_stock(unsigned long flags,
+				 bool stock_lock_acquried)
 {
-	if (likely(in_task()))
-		preempt_enable();
-	else
-		local_irq_restore(flags);
+#ifndef CONFIG_PREEMPTION
+	if (likely(!stock_lock_acquried)) {
+		local_unlock(&memcg_stock.task_obj_lock);
+		return;
+	}
+#endif
+	local_unlock_irqrestore(&memcg_stock.stock_lock, flags);
 }
 
 /*
@@ -2985,7 +2948,8 @@ static void memcg_free_cache_id(int id)
  * @nr_pages: number of pages to uncharge
  */
 static void obj_cgroup_uncharge_pages(struct obj_cgroup *objcg,
-				      unsigned int nr_pages)
+				      unsigned int nr_pages,
+				      bool stock_lock_acquried)
 {
 	struct mem_cgroup *memcg;
 
@@ -2993,7 +2957,7 @@ static void obj_cgroup_uncharge_pages(struct obj_cgroup *objcg,
 
 	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
 		page_counter_uncharge(&memcg->kmem, nr_pages);
-	refill_stock(memcg, nr_pages);
+	refill_stock(memcg, nr_pages, stock_lock_acquried);
 
 	css_put(&memcg->css);
 }
@@ -3067,7 +3031,7 @@ void __memcg_kmem_uncharge_page(struct page *page, int order)
 		return;
 
 	objcg = __folio_objcg(folio);
-	obj_cgroup_uncharge_pages(objcg, nr_pages);
+	obj_cgroup_uncharge_pages(objcg, nr_pages, false);
 	folio->memcg_data = 0;
 	obj_cgroup_put(objcg);
 }
@@ -3075,17 +3039,21 @@ void __memcg_kmem_uncharge_page(struct page *page, int order)
 void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat,
 		     enum node_stat_item idx, int nr)
 {
+	bool stock_lock_acquried;
 	unsigned long flags;
-	struct obj_stock *stock = get_obj_stock(&flags);
+	struct obj_cgroup *old = NULL;
+	struct obj_stock *stock;
 	int *bytes;
 
+	stock = get_obj_stock(&flags, &stock_lock_acquried);
 	/*
 	 * Save vmstat data in stock and skip vmstat array update unless
 	 * accumulating over a page of vmstat data or when pgdat or idx
 	 * changes.
 	 */
 	if (stock->cached_objcg != objcg) {
-		drain_obj_stock(stock);
+		old = drain_obj_stock(stock, stock_lock_acquried);
+
 		obj_cgroup_get(objcg);
 		stock->nr_bytes = atomic_read(&objcg->nr_charged_bytes)
 				? atomic_xchg(&objcg->nr_charged_bytes, 0) : 0;
@@ -3129,38 +3097,43 @@ void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat,
 	if (nr)
 		mod_objcg_mlstate(objcg, pgdat, idx, nr);
 
-	put_obj_stock(flags);
+	put_obj_stock(flags, stock_lock_acquried);
+	if (old)
+		obj_cgroup_put(old);
 }
 
 static bool consume_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes)
 {
+	bool stock_lock_acquried;
 	unsigned long flags;
-	struct obj_stock *stock = get_obj_stock(&flags);
+	struct obj_stock *stock;
 	bool ret = false;
 
+	stock = get_obj_stock(&flags, &stock_lock_acquried);
 	if (objcg == stock->cached_objcg && stock->nr_bytes >= nr_bytes) {
 		stock->nr_bytes -= nr_bytes;
 		ret = true;
 	}
 
-	put_obj_stock(flags);
+	put_obj_stock(flags, stock_lock_acquried);
 
 	return ret;
 }
 
-static void drain_obj_stock(struct obj_stock *stock)
+static struct obj_cgroup *drain_obj_stock(struct obj_stock *stock,
+					  bool stock_lock_acquried)
 {
 	struct obj_cgroup *old = stock->cached_objcg;
 
 	if (!old)
-		return;
+		return NULL;
 
 	if (stock->nr_bytes) {
 		unsigned int nr_pages = stock->nr_bytes >> PAGE_SHIFT;
 		unsigned int nr_bytes = stock->nr_bytes & (PAGE_SIZE - 1);
 
 		if (nr_pages)
-			obj_cgroup_uncharge_pages(old, nr_pages);
+			obj_cgroup_uncharge_pages(old, nr_pages, stock_lock_acquried);
 
 		/*
 		 * The leftover is flushed to the centralized per-memcg value.
@@ -3195,8 +3168,8 @@ static void drain_obj_stock(struct obj_stock *stock)
 		stock->cached_pgdat = NULL;
 	}
 
-	obj_cgroup_put(old);
 	stock->cached_objcg = NULL;
+	return old;
 }
 
 static bool obj_stock_flush_required(struct memcg_stock_pcp *stock,
@@ -3204,11 +3177,13 @@ static bool obj_stock_flush_required(struct memcg_stock_pcp *stock,
 {
 	struct mem_cgroup *memcg;
 
+#ifndef CONFIG_PREEMPTION
 	if (in_task() && stock->task_obj.cached_objcg) {
 		memcg = obj_cgroup_memcg(stock->task_obj.cached_objcg);
 		if (memcg && mem_cgroup_is_descendant(memcg, root_memcg))
 			return true;
 	}
+#endif
 	if (stock->irq_obj.cached_objcg) {
 		memcg = obj_cgroup_memcg(stock->irq_obj.cached_objcg);
 		if (memcg && mem_cgroup_is_descendant(memcg, root_memcg))
@@ -3221,12 +3196,15 @@ static bool obj_stock_flush_required(struct memcg_stock_pcp *stock,
 static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes,
 			     bool allow_uncharge)
 {
+	bool stock_lock_acquried;
 	unsigned long flags;
-	struct obj_stock *stock = get_obj_stock(&flags);
+	struct obj_stock *stock;
 	unsigned int nr_pages = 0;
+	struct obj_cgroup *old = NULL;
 
+	stock = get_obj_stock(&flags, &stock_lock_acquried);
 	if (stock->cached_objcg != objcg) { /* reset if necessary */
-		drain_obj_stock(stock);
+		old = drain_obj_stock(stock, stock_lock_acquried);
 		obj_cgroup_get(objcg);
 		stock->cached_objcg = objcg;
 		stock->nr_bytes = atomic_read(&objcg->nr_charged_bytes)
@@ -3240,10 +3218,12 @@ static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes,
 		stock->nr_bytes &= (PAGE_SIZE - 1);
 	}
 
-	put_obj_stock(flags);
+	put_obj_stock(flags, stock_lock_acquried);
+	if (old)
+		obj_cgroup_put(old);
 
 	if (nr_pages)
-		obj_cgroup_uncharge_pages(objcg, nr_pages);
+		obj_cgroup_uncharge_pages(objcg, nr_pages, false);
 }
 
 int obj_cgroup_charge(struct obj_cgroup *objcg, gfp_t gfp, size_t size)
@@ -3763,8 +3743,12 @@ static ssize_t mem_cgroup_write(struct kernfs_open_file *of,
 		}
 		break;
 	case RES_SOFT_LIMIT:
+#ifndef CONFIG_PREEMPT_RT
 		memcg->soft_limit = nr_pages;
 		ret = 0;
+#else
+		ret = -EOPNOTSUPP;
+#endif
 		break;
 	}
 	return ret ?: nbytes;
@@ -4069,82 +4053,6 @@ static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css,
 	return 0;
 }
 
-static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
-{
-	struct mem_cgroup_threshold_ary *t;
-	unsigned long usage;
-	int i;
-
-	rcu_read_lock();
-	if (!swap)
-		t = rcu_dereference(memcg->thresholds.primary);
-	else
-		t = rcu_dereference(memcg->memsw_thresholds.primary);
-
-	if (!t)
-		goto unlock;
-
-	usage = mem_cgroup_usage(memcg, swap);
-
-	/*
-	 * current_threshold points to threshold just below or equal to usage.
-	 * If it's not true, a threshold was crossed after last
-	 * call of __mem_cgroup_threshold().
-	 */
-	i = t->current_threshold;
-
-	/*
-	 * Iterate backward over array of thresholds starting from
-	 * current_threshold and check if a threshold is crossed.
-	 * If none of thresholds below usage is crossed, we read
-	 * only one element of the array here.
-	 */
-	for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--)
-		eventfd_signal(t->entries[i].eventfd, 1);
-
-	/* i = current_threshold + 1 */
-	i++;
-
-	/*
-	 * Iterate forward over array of thresholds starting from
-	 * current_threshold+1 and check if a threshold is crossed.
-	 * If none of thresholds above usage is crossed, we read
-	 * only one element of the array here.
-	 */
-	for (; i < t->size && unlikely(t->entries[i].threshold <= usage); i++)
-		eventfd_signal(t->entries[i].eventfd, 1);
-
-	/* Update current_threshold */
-	t->current_threshold = i - 1;
-unlock:
-	rcu_read_unlock();
-}
-
-static void mem_cgroup_threshold(struct mem_cgroup *memcg)
-{
-	while (memcg) {
-		__mem_cgroup_threshold(memcg, false);
-		if (do_memsw_account())
-			__mem_cgroup_threshold(memcg, true);
-
-		memcg = parent_mem_cgroup(memcg);
-	}
-}
-
-static int compare_thresholds(const void *a, const void *b)
-{
-	const struct mem_cgroup_threshold *_a = a;
-	const struct mem_cgroup_threshold *_b = b;
-
-	if (_a->threshold > _b->threshold)
-		return 1;
-
-	if (_a->threshold < _b->threshold)
-		return -1;
-
-	return 0;
-}
-
 static int mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg)
 {
 	struct mem_cgroup_eventfd_list *ev;
@@ -4166,234 +4074,6 @@ static void mem_cgroup_oom_notify(struct mem_cgroup *memcg)
 		mem_cgroup_oom_notify_cb(iter);
 }
 
-static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
-	struct eventfd_ctx *eventfd, const char *args, enum res_type type)
-{
-	struct mem_cgroup_thresholds *thresholds;
-	struct mem_cgroup_threshold_ary *new;
-	unsigned long threshold;
-	unsigned long usage;
-	int i, size, ret;
-
-	ret = page_counter_memparse(args, "-1", &threshold);
-	if (ret)
-		return ret;
-
-	mutex_lock(&memcg->thresholds_lock);
-
-	if (type == _MEM) {
-		thresholds = &memcg->thresholds;
-		usage = mem_cgroup_usage(memcg, false);
-	} else if (type == _MEMSWAP) {
-		thresholds = &memcg->memsw_thresholds;
-		usage = mem_cgroup_usage(memcg, true);
-	} else
-		BUG();
-
-	/* Check if a threshold crossed before adding a new one */
-	if (thresholds->primary)
-		__mem_cgroup_threshold(memcg, type == _MEMSWAP);
-
-	size = thresholds->primary ? thresholds->primary->size + 1 : 1;
-
-	/* Allocate memory for new array of thresholds */
-	new = kmalloc(struct_size(new, entries, size), GFP_KERNEL);
-	if (!new) {
-		ret = -ENOMEM;
-		goto unlock;
-	}
-	new->size = size;
-
-	/* Copy thresholds (if any) to new array */
-	if (thresholds->primary)
-		memcpy(new->entries, thresholds->primary->entries,
-		       flex_array_size(new, entries, size - 1));
-
-	/* Add new threshold */
-	new->entries[size - 1].eventfd = eventfd;
-	new->entries[size - 1].threshold = threshold;
-
-	/* Sort thresholds. Registering of new threshold isn't time-critical */
-	sort(new->entries, size, sizeof(*new->entries),
-			compare_thresholds, NULL);
-
-	/* Find current threshold */
-	new->current_threshold = -1;
-	for (i = 0; i < size; i++) {
-		if (new->entries[i].threshold <= usage) {
-			/*
-			 * new->current_threshold will not be used until
-			 * rcu_assign_pointer(), so it's safe to increment
-			 * it here.
-			 */
-			++new->current_threshold;
-		} else
-			break;
-	}
-
-	/* Free old spare buffer and save old primary buffer as spare */
-	kfree(thresholds->spare);
-	thresholds->spare = thresholds->primary;
-
-	rcu_assign_pointer(thresholds->primary, new);
-
-	/* To be sure that nobody uses thresholds */
-	synchronize_rcu();
-
-unlock:
-	mutex_unlock(&memcg->thresholds_lock);
-
-	return ret;
-}
-
-static int mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
-	struct eventfd_ctx *eventfd, const char *args)
-{
-	return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEM);
-}
-
-static int memsw_cgroup_usage_register_event(struct mem_cgroup *memcg,
-	struct eventfd_ctx *eventfd, const char *args)
-{
-	return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEMSWAP);
-}
-
-static void __mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
-	struct eventfd_ctx *eventfd, enum res_type type)
-{
-	struct mem_cgroup_thresholds *thresholds;
-	struct mem_cgroup_threshold_ary *new;
-	unsigned long usage;
-	int i, j, size, entries;
-
-	mutex_lock(&memcg->thresholds_lock);
-
-	if (type == _MEM) {
-		thresholds = &memcg->thresholds;
-		usage = mem_cgroup_usage(memcg, false);
-	} else if (type == _MEMSWAP) {
-		thresholds = &memcg->memsw_thresholds;
-		usage = mem_cgroup_usage(memcg, true);
-	} else
-		BUG();
-
-	if (!thresholds->primary)
-		goto unlock;
-
-	/* Check if a threshold crossed before removing */
-	__mem_cgroup_threshold(memcg, type == _MEMSWAP);
-
-	/* Calculate new number of threshold */
-	size = entries = 0;
-	for (i = 0; i < thresholds->primary->size; i++) {
-		if (thresholds->primary->entries[i].eventfd != eventfd)
-			size++;
-		else
-			entries++;
-	}
-
-	new = thresholds->spare;
-
-	/* If no items related to eventfd have been cleared, nothing to do */
-	if (!entries)
-		goto unlock;
-
-	/* Set thresholds array to NULL if we don't have thresholds */
-	if (!size) {
-		kfree(new);
-		new = NULL;
-		goto swap_buffers;
-	}
-
-	new->size = size;
-
-	/* Copy thresholds and find current threshold */
-	new->current_threshold = -1;
-	for (i = 0, j = 0; i < thresholds->primary->size; i++) {
-		if (thresholds->primary->entries[i].eventfd == eventfd)
-			continue;
-
-		new->entries[j] = thresholds->primary->entries[i];
-		if (new->entries[j].threshold <= usage) {
-			/*
-			 * new->current_threshold will not be used
-			 * until rcu_assign_pointer(), so it's safe to increment
-			 * it here.
-			 */
-			++new->current_threshold;
-		}
-		j++;
-	}
-
-swap_buffers:
-	/* Swap primary and spare array */
-	thresholds->spare = thresholds->primary;
-
-	rcu_assign_pointer(thresholds->primary, new);
-
-	/* To be sure that nobody uses thresholds */
-	synchronize_rcu();
-
-	/* If all events are unregistered, free the spare array */
-	if (!new) {
-		kfree(thresholds->spare);
-		thresholds->spare = NULL;
-	}
-unlock:
-	mutex_unlock(&memcg->thresholds_lock);
-}
-
-static void mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
-	struct eventfd_ctx *eventfd)
-{
-	return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEM);
-}
-
-static void memsw_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
-	struct eventfd_ctx *eventfd)
-{
-	return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEMSWAP);
-}
-
-static int mem_cgroup_oom_register_event(struct mem_cgroup *memcg,
-	struct eventfd_ctx *eventfd, const char *args)
-{
-	struct mem_cgroup_eventfd_list *event;
-
-	event = kmalloc(sizeof(*event),	GFP_KERNEL);
-	if (!event)
-		return -ENOMEM;
-
-	spin_lock(&memcg_oom_lock);
-
-	event->eventfd = eventfd;
-	list_add(&event->list, &memcg->oom_notify);
-
-	/* already in OOM ? */
-	if (memcg->under_oom)
-		eventfd_signal(eventfd, 1);
-	spin_unlock(&memcg_oom_lock);
-
-	return 0;
-}
-
-static void mem_cgroup_oom_unregister_event(struct mem_cgroup *memcg,
-	struct eventfd_ctx *eventfd)
-{
-	struct mem_cgroup_eventfd_list *ev, *tmp;
-
-	spin_lock(&memcg_oom_lock);
-
-	list_for_each_entry_safe(ev, tmp, &memcg->oom_notify, list) {
-		if (ev->eventfd == eventfd) {
-			list_del(&ev->list);
-			kfree(ev);
-		}
-	}
-
-	spin_unlock(&memcg_oom_lock);
-}
-
 static int mem_cgroup_oom_control_read(struct seq_file *sf, void *v)
 {
 	struct mem_cgroup *memcg = mem_cgroup_from_seq(sf);
@@ -4634,6 +4314,7 @@ static void memcg_wb_domain_size_changed(struct mem_cgroup *memcg)
 
 #endif	/* CONFIG_CGROUP_WRITEBACK */
 
+#ifndef CONFIG_PREEMPT_RT
 /*
  * DO NOT USE IN NEW FILES.
  *
@@ -4647,6 +4328,391 @@ static void memcg_wb_domain_size_changed(struct mem_cgroup *memcg)
  * possible.
  */
 
+static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
+				       enum mem_cgroup_events_target target)
+{
+	unsigned long val, next;
+
+	val = __this_cpu_read(memcg->vmstats_percpu->nr_page_events);
+	next = __this_cpu_read(memcg->vmstats_percpu->targets[target]);
+	/* from time_after() in jiffies.h */
+	if ((long)(next - val) < 0) {
+		switch (target) {
+		case MEM_CGROUP_TARGET_THRESH:
+			next = val + THRESHOLDS_EVENTS_TARGET;
+			break;
+		case MEM_CGROUP_TARGET_SOFTLIMIT:
+			next = val + SOFTLIMIT_EVENTS_TARGET;
+			break;
+		default:
+			break;
+		}
+		__this_cpu_write(memcg->vmstats_percpu->targets[target], next);
+		return true;
+	}
+	return false;
+}
+
+static void mem_cgroup_update_tree(struct mem_cgroup *memcg, int nid)
+{
+	unsigned long excess;
+	struct mem_cgroup_per_node *mz;
+	struct mem_cgroup_tree_per_node *mctz;
+
+	mctz = soft_limit_tree.rb_tree_per_node[nid];
+	if (!mctz)
+		return;
+	/*
+	 * Necessary to update all ancestors when hierarchy is used.
+	 * because their event counter is not touched.
+	 */
+	for (; memcg; memcg = parent_mem_cgroup(memcg)) {
+		mz = memcg->nodeinfo[nid];
+		excess = soft_limit_excess(memcg);
+		/*
+		 * We have to update the tree if mz is on RB-tree or
+		 * mem is over its softlimit.
+		 */
+		if (excess || mz->on_tree) {
+			unsigned long flags;
+
+			spin_lock_irqsave(&mctz->lock, flags);
+			/* if on-tree, remove it */
+			if (mz->on_tree)
+				__mem_cgroup_remove_exceeded(mz, mctz);
+			/*
+			 * Insert again. mz->usage_in_excess will be updated.
+			 * If excess is 0, no tree ops.
+			 */
+			__mem_cgroup_insert_exceeded(mz, mctz, excess);
+			spin_unlock_irqrestore(&mctz->lock, flags);
+		}
+	}
+}
+
+static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
+{
+	struct mem_cgroup_threshold_ary *t;
+	unsigned long usage;
+	int i;
+
+	rcu_read_lock();
+	if (!swap)
+		t = rcu_dereference(memcg->thresholds.primary);
+	else
+		t = rcu_dereference(memcg->memsw_thresholds.primary);
+
+	if (!t)
+		goto unlock;
+
+	usage = mem_cgroup_usage(memcg, swap);
+
+	/*
+	 * current_threshold points to threshold just below or equal to usage.
+	 * If it's not true, a threshold was crossed after last
+	 * call of __mem_cgroup_threshold().
+	 */
+	i = t->current_threshold;
+
+	/*
+	 * Iterate backward over array of thresholds starting from
+	 * current_threshold and check if a threshold is crossed.
+	 * If none of thresholds below usage is crossed, we read
+	 * only one element of the array here.
+	 */
+	for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--)
+		eventfd_signal(t->entries[i].eventfd, 1);
+
+	/* i = current_threshold + 1 */
+	i++;
+
+	/*
+	 * Iterate forward over array of thresholds starting from
+	 * current_threshold+1 and check if a threshold is crossed.
+	 * If none of thresholds above usage is crossed, we read
+	 * only one element of the array here.
+	 */
+	for (; i < t->size && unlikely(t->entries[i].threshold <= usage); i++)
+		eventfd_signal(t->entries[i].eventfd, 1);
+
+	/* Update current_threshold */
+	t->current_threshold = i - 1;
+unlock:
+	rcu_read_unlock();
+}
+
+static void mem_cgroup_threshold(struct mem_cgroup *memcg)
+{
+	while (memcg) {
+		__mem_cgroup_threshold(memcg, false);
+		if (do_memsw_account())
+			__mem_cgroup_threshold(memcg, true);
+
+		memcg = parent_mem_cgroup(memcg);
+	}
+}
+
+/*
+ * Check events in order.
+ *
+ */
+static void memcg_check_events(struct mem_cgroup *memcg, int nid)
+{
+	/* threshold event is triggered in finer grain than soft limit */
+	if (unlikely(mem_cgroup_event_ratelimit(memcg,
+						MEM_CGROUP_TARGET_THRESH))) {
+		bool do_softlimit;
+
+		do_softlimit = mem_cgroup_event_ratelimit(memcg,
+						MEM_CGROUP_TARGET_SOFTLIMIT);
+		mem_cgroup_threshold(memcg);
+		if (unlikely(do_softlimit))
+			mem_cgroup_update_tree(memcg, nid);
+	}
+}
+
+static int compare_thresholds(const void *a, const void *b)
+{
+	const struct mem_cgroup_threshold *_a = a;
+	const struct mem_cgroup_threshold *_b = b;
+
+	if (_a->threshold > _b->threshold)
+		return 1;
+
+	if (_a->threshold < _b->threshold)
+		return -1;
+
+	return 0;
+}
+
+static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
+	struct eventfd_ctx *eventfd, const char *args, enum res_type type)
+{
+	struct mem_cgroup_thresholds *thresholds;
+	struct mem_cgroup_threshold_ary *new;
+	unsigned long threshold;
+	unsigned long usage;
+	int i, size, ret;
+
+	ret = page_counter_memparse(args, "-1", &threshold);
+	if (ret)
+		return ret;
+
+	mutex_lock(&memcg->thresholds_lock);
+
+	if (type == _MEM) {
+		thresholds = &memcg->thresholds;
+		usage = mem_cgroup_usage(memcg, false);
+	} else if (type == _MEMSWAP) {
+		thresholds = &memcg->memsw_thresholds;
+		usage = mem_cgroup_usage(memcg, true);
+	} else
+		BUG();
+
+	/* Check if a threshold crossed before adding a new one */
+	if (thresholds->primary)
+		__mem_cgroup_threshold(memcg, type == _MEMSWAP);
+
+	size = thresholds->primary ? thresholds->primary->size + 1 : 1;
+
+	/* Allocate memory for new array of thresholds */
+	new = kmalloc(struct_size(new, entries, size), GFP_KERNEL);
+	if (!new) {
+		ret = -ENOMEM;
+		goto unlock;
+	}
+	new->size = size;
+
+	/* Copy thresholds (if any) to new array */
+	if (thresholds->primary)
+		memcpy(new->entries, thresholds->primary->entries,
+		       flex_array_size(new, entries, size - 1));
+
+	/* Add new threshold */
+	new->entries[size - 1].eventfd = eventfd;
+	new->entries[size - 1].threshold = threshold;
+
+	/* Sort thresholds. Registering of new threshold isn't time-critical */
+	sort(new->entries, size, sizeof(*new->entries),
+			compare_thresholds, NULL);
+
+	/* Find current threshold */
+	new->current_threshold = -1;
+	for (i = 0; i < size; i++) {
+		if (new->entries[i].threshold <= usage) {
+			/*
+			 * new->current_threshold will not be used until
+			 * rcu_assign_pointer(), so it's safe to increment
+			 * it here.
+			 */
+			++new->current_threshold;
+		} else
+			break;
+	}
+
+	/* Free old spare buffer and save old primary buffer as spare */
+	kfree(thresholds->spare);
+	thresholds->spare = thresholds->primary;
+
+	rcu_assign_pointer(thresholds->primary, new);
+
+	/* To be sure that nobody uses thresholds */
+	synchronize_rcu();
+
+unlock:
+	mutex_unlock(&memcg->thresholds_lock);
+
+	return ret;
+}
+
+static int mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
+	struct eventfd_ctx *eventfd, const char *args)
+{
+	return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEM);
+}
+
+static int memsw_cgroup_usage_register_event(struct mem_cgroup *memcg,
+	struct eventfd_ctx *eventfd, const char *args)
+{
+	return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEMSWAP);
+}
+
+static void __mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
+	struct eventfd_ctx *eventfd, enum res_type type)
+{
+	struct mem_cgroup_thresholds *thresholds;
+	struct mem_cgroup_threshold_ary *new;
+	unsigned long usage;
+	int i, j, size, entries;
+
+	mutex_lock(&memcg->thresholds_lock);
+
+	if (type == _MEM) {
+		thresholds = &memcg->thresholds;
+		usage = mem_cgroup_usage(memcg, false);
+	} else if (type == _MEMSWAP) {
+		thresholds = &memcg->memsw_thresholds;
+		usage = mem_cgroup_usage(memcg, true);
+	} else
+		BUG();
+
+	if (!thresholds->primary)
+		goto unlock;
+
+	/* Check if a threshold crossed before removing */
+	__mem_cgroup_threshold(memcg, type == _MEMSWAP);
+
+	/* Calculate new number of threshold */
+	size = entries = 0;
+	for (i = 0; i < thresholds->primary->size; i++) {
+		if (thresholds->primary->entries[i].eventfd != eventfd)
+			size++;
+		else
+			entries++;
+	}
+
+	new = thresholds->spare;
+
+	/* If no items related to eventfd have been cleared, nothing to do */
+	if (!entries)
+		goto unlock;
+
+	/* Set thresholds array to NULL if we don't have thresholds */
+	if (!size) {
+		kfree(new);
+		new = NULL;
+		goto swap_buffers;
+	}
+
+	new->size = size;
+
+	/* Copy thresholds and find current threshold */
+	new->current_threshold = -1;
+	for (i = 0, j = 0; i < thresholds->primary->size; i++) {
+		if (thresholds->primary->entries[i].eventfd == eventfd)
+			continue;
+
+		new->entries[j] = thresholds->primary->entries[i];
+		if (new->entries[j].threshold <= usage) {
+			/*
+			 * new->current_threshold will not be used
+			 * until rcu_assign_pointer(), so it's safe to increment
+			 * it here.
+			 */
+			++new->current_threshold;
+		}
+		j++;
+	}
+
+swap_buffers:
+	/* Swap primary and spare array */
+	thresholds->spare = thresholds->primary;
+
+	rcu_assign_pointer(thresholds->primary, new);
+
+	/* To be sure that nobody uses thresholds */
+	synchronize_rcu();
+
+	/* If all events are unregistered, free the spare array */
+	if (!new) {
+		kfree(thresholds->spare);
+		thresholds->spare = NULL;
+	}
+unlock:
+	mutex_unlock(&memcg->thresholds_lock);
+}
+
+static void mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
+	struct eventfd_ctx *eventfd)
+{
+	return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEM);
+}
+
+static void memsw_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
+	struct eventfd_ctx *eventfd)
+{
+	return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEMSWAP);
+}
+
+static int mem_cgroup_oom_register_event(struct mem_cgroup *memcg,
+	struct eventfd_ctx *eventfd, const char *args)
+{
+	struct mem_cgroup_eventfd_list *event;
+
+	event = kmalloc(sizeof(*event),	GFP_KERNEL);
+	if (!event)
+		return -ENOMEM;
+
+	spin_lock(&memcg_oom_lock);
+
+	event->eventfd = eventfd;
+	list_add(&event->list, &memcg->oom_notify);
+
+	/* already in OOM ? */
+	if (memcg->under_oom)
+		eventfd_signal(eventfd, 1);
+	spin_unlock(&memcg_oom_lock);
+
+	return 0;
+}
+
+static void mem_cgroup_oom_unregister_event(struct mem_cgroup *memcg,
+	struct eventfd_ctx *eventfd)
+{
+	struct mem_cgroup_eventfd_list *ev, *tmp;
+
+	spin_lock(&memcg_oom_lock);
+
+	list_for_each_entry_safe(ev, tmp, &memcg->oom_notify, list) {
+		if (ev->eventfd == eventfd) {
+			list_del(&ev->list);
+			kfree(ev);
+		}
+	}
+
+	spin_unlock(&memcg_oom_lock);
+}
+
 /*
  * Unregister event and free resources.
  *
@@ -4857,6 +4923,18 @@ static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
 	return ret;
 }
 
+#else
+
+static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
+					 char *buf, size_t nbytes, loff_t off)
+{
+	return -EOPNOTSUPP;
+}
+
+static void memcg_check_events(struct mem_cgroup *memcg, int nid) { }
+
+#endif
+
 #if defined(CONFIG_MEMCG_KMEM) && (defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG))
 static int mem_cgroup_slab_show(struct seq_file *m, void *p)
 {
@@ -7038,7 +7116,7 @@ void mem_cgroup_uncharge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages)
 
 	mod_memcg_state(memcg, MEMCG_SOCK, -nr_pages);
 
-	refill_stock(memcg, nr_pages);
+	refill_stock(memcg, nr_pages, false);
 }
 
 static int __init cgroup_memory(char *s)
@@ -7178,9 +7256,18 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
 	 * i_pages lock which is taken with interrupts-off. It is
 	 * important here to have the interrupts disabled because it is the
 	 * only synchronisation we have for updating the per-CPU variables.
+	 * On PREEMPT_RT interrupts are never disabled and the updates to per-CPU
+	 * variables are synchronised by keeping preemption disabled.
 	 */
-	VM_BUG_ON(!irqs_disabled());
-	mem_cgroup_charge_statistics(memcg, -nr_entries);
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT)) {
+		VM_BUG_ON(!irqs_disabled());
+		mem_cgroup_charge_statistics(memcg, -nr_entries);
+	} else {
+		preempt_disable();
+		mem_cgroup_charge_statistics(memcg, -nr_entries);
+		preempt_enable();
+	}
+
 	memcg_check_events(memcg, page_to_nid(page));
 
 	css_put(&memcg->css);
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 4165304d35471..0aeae4a15fdab 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1924,11 +1924,12 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask)
 		return ERR_PTR(err);
 	}
 
-	vbq = &get_cpu_var(vmap_block_queue);
+	get_cpu_light();
+	vbq = this_cpu_ptr(&vmap_block_queue);
 	spin_lock(&vbq->lock);
 	list_add_tail_rcu(&vb->free_list, &vbq->free);
 	spin_unlock(&vbq->lock);
-	put_cpu_var(vmap_block_queue);
+	put_cpu_light();
 
 	return vaddr;
 }
@@ -2007,7 +2008,8 @@ static void *vb_alloc(unsigned long size, gfp_t gfp_mask)
 	order = get_order(size);
 
 	rcu_read_lock();
-	vbq = &get_cpu_var(vmap_block_queue);
+	get_cpu_light();
+	vbq = this_cpu_ptr(&vmap_block_queue);
 	list_for_each_entry_rcu(vb, &vbq->free, free_list) {
 		unsigned long pages_off;
 
@@ -2030,7 +2032,7 @@ static void *vb_alloc(unsigned long size, gfp_t gfp_mask)
 		break;
 	}
 
-	put_cpu_var(vmap_block_queue);
+	put_cpu_light();
 	rcu_read_unlock();
 
 	/* Allocate new block if nothing was found */
diff --git a/mm/workingset.c b/mm/workingset.c
index 8c03afe1d67cb..4579883eb1091 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -433,6 +433,8 @@ static struct list_lru shadow_nodes;
 
 void workingset_update_node(struct xa_node *node)
 {
+	struct address_space *mapping;
+
 	/*
 	 * Track non-empty nodes that contain only shadow entries;
 	 * unlink those that contain pages or are being freed.
@@ -441,7 +443,8 @@ void workingset_update_node(struct xa_node *node)
 	 * already where they should be. The list_empty() test is safe
 	 * as node->private_list is protected by the i_pages lock.
 	 */
-	VM_WARN_ON_ONCE(!irqs_disabled());  /* For __inc_lruvec_page_state */
+	mapping = container_of(node->array, struct address_space, i_pages);
+	lockdep_assert_held(&mapping->i_pages.xa_lock);
 
 	if (node->count && node->count == node->nr_values) {
 		if (list_empty(&node->private_list)) {
diff --git a/net/core/dev.c b/net/core/dev.c
index 1baab07820f65..7ac37cbc42df4 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -216,18 +216,38 @@ static inline struct hlist_head *dev_index_hash(struct net *net, int ifindex)
 	return &net->dev_index_head[ifindex & (NETDEV_HASHENTRIES - 1)];
 }
 
-static inline void rps_lock(struct softnet_data *sd)
+static inline void rps_lock_irqsave(struct softnet_data *sd,
+				    unsigned long *flags)
 {
-#ifdef CONFIG_RPS
-	spin_lock(&sd->input_pkt_queue.lock);
-#endif
+	if (IS_ENABLED(CONFIG_RPS))
+		spin_lock_irqsave(&sd->input_pkt_queue.lock, *flags);
+	else if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_save(*flags);
 }
 
-static inline void rps_unlock(struct softnet_data *sd)
+static inline void rps_lock_irq_disable(struct softnet_data *sd)
 {
-#ifdef CONFIG_RPS
-	spin_unlock(&sd->input_pkt_queue.lock);
-#endif
+	if (IS_ENABLED(CONFIG_RPS))
+		spin_lock_irq(&sd->input_pkt_queue.lock);
+	else if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_disable();
+}
+
+static inline void rps_unlock_irq_restore(struct softnet_data *sd,
+					  unsigned long *flags)
+{
+	if (IS_ENABLED(CONFIG_RPS))
+		spin_unlock_irqrestore(&sd->input_pkt_queue.lock, *flags);
+	else if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_restore(*flags);
+}
+
+static inline void rps_unlock_irq_enable(struct softnet_data *sd)
+{
+	if (IS_ENABLED(CONFIG_RPS))
+		spin_unlock_irq(&sd->input_pkt_queue.lock);
+	else if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_enable();
 }
 
 static struct netdev_name_node *netdev_name_node_alloc(struct net_device *dev,
@@ -2965,6 +2985,7 @@ static void __netif_reschedule(struct Qdisc *q)
 	sd->output_queue_tailp = &q->next_sched;
 	raise_softirq_irqoff(NET_TX_SOFTIRQ);
 	local_irq_restore(flags);
+	preempt_check_resched_rt();
 }
 
 void __netif_schedule(struct Qdisc *q)
@@ -3027,6 +3048,7 @@ void __dev_kfree_skb_irq(struct sk_buff *skb, enum skb_free_reason reason)
 	__this_cpu_write(softnet_data.completion_queue, skb);
 	raise_softirq_irqoff(NET_TX_SOFTIRQ);
 	local_irq_restore(flags);
+	preempt_check_resched_rt();
 }
 EXPORT_SYMBOL(__dev_kfree_skb_irq);
 
@@ -4456,11 +4478,11 @@ static void rps_trigger_softirq(void *data)
  * If yes, queue it to our IPI list and return 1
  * If no, return 0
  */
-static int rps_ipi_queued(struct softnet_data *sd)
+static int napi_schedule_rps(struct softnet_data *sd)
 {
-#ifdef CONFIG_RPS
 	struct softnet_data *mysd = this_cpu_ptr(&softnet_data);
 
+#ifdef CONFIG_RPS
 	if (sd != mysd) {
 		sd->rps_ipi_next = mysd->rps_ipi_list;
 		mysd->rps_ipi_list = sd;
@@ -4469,6 +4491,7 @@ static int rps_ipi_queued(struct softnet_data *sd)
 		return 1;
 	}
 #endif /* CONFIG_RPS */
+	__napi_schedule_irqoff(&mysd->backlog);
 	return 0;
 }
 
@@ -4525,9 +4548,7 @@ static int enqueue_to_backlog(struct sk_buff *skb, int cpu,
 
 	sd = &per_cpu(softnet_data, cpu);
 
-	local_irq_save(flags);
-
-	rps_lock(sd);
+	rps_lock_irqsave(sd, &flags);
 	if (!netif_running(skb->dev))
 		goto drop;
 	qlen = skb_queue_len(&sd->input_pkt_queue);
@@ -4536,26 +4557,21 @@ static int enqueue_to_backlog(struct sk_buff *skb, int cpu,
 enqueue:
 			__skb_queue_tail(&sd->input_pkt_queue, skb);
 			input_queue_tail_incr_save(sd, qtail);
-			rps_unlock(sd);
-			local_irq_restore(flags);
+			rps_unlock_irq_restore(sd, &flags);
 			return NET_RX_SUCCESS;
 		}
 
 		/* Schedule NAPI for backlog device
 		 * We can use non atomic operation since we own the queue lock
 		 */
-		if (!__test_and_set_bit(NAPI_STATE_SCHED, &sd->backlog.state)) {
-			if (!rps_ipi_queued(sd))
-				____napi_schedule(sd, &sd->backlog);
-		}
+		if (!__test_and_set_bit(NAPI_STATE_SCHED, &sd->backlog.state))
+			napi_schedule_rps(sd);
 		goto enqueue;
 	}
 
 drop:
 	sd->dropped++;
-	rps_unlock(sd);
-
-	local_irq_restore(flags);
+	rps_unlock_irq_restore(sd, &flags);
 
 	atomic_long_inc(&skb->dev->rx_dropped);
 	kfree_skb(skb);
@@ -4796,7 +4812,6 @@ static int netif_rx_internal(struct sk_buff *skb)
 		struct rps_dev_flow voidflow, *rflow = &voidflow;
 		int cpu;
 
-		preempt_disable();
 		rcu_read_lock();
 
 		cpu = get_rps_cpu(skb->dev, skb, &rflow);
@@ -4806,18 +4821,26 @@ static int netif_rx_internal(struct sk_buff *skb)
 		ret = enqueue_to_backlog(skb, cpu, &rflow->last_qtail);
 
 		rcu_read_unlock();
-		preempt_enable();
 	} else
 #endif
 	{
 		unsigned int qtail;
 
-		ret = enqueue_to_backlog(skb, get_cpu(), &qtail);
-		put_cpu();
+		ret = enqueue_to_backlog(skb, smp_processor_id(), &qtail);
 	}
 	return ret;
 }
 
+int __netif_rx(struct sk_buff *skb)
+{
+	int ret;
+
+	trace_netif_rx_entry(skb);
+	ret = netif_rx_internal(skb);
+	trace_netif_rx_exit(ret);
+	return ret;
+}
+
 /**
  *	netif_rx	-	post buffer to the network code
  *	@skb: buffer to post
@@ -4826,58 +4849,25 @@ static int netif_rx_internal(struct sk_buff *skb)
  *	the upper (protocol) levels to process.  It always succeeds. The buffer
  *	may be dropped during processing for congestion control or by the
  *	protocol layers.
+ *	This interface is considered legacy. Modern NIC driver should use NAPI
+ *	and GRO.
  *
  *	return values:
  *	NET_RX_SUCCESS	(no congestion)
  *	NET_RX_DROP     (packet was dropped)
  *
  */
-
 int netif_rx(struct sk_buff *skb)
 {
 	int ret;
 
-	trace_netif_rx_entry(skb);
-
-	ret = netif_rx_internal(skb);
-	trace_netif_rx_exit(ret);
-
+	local_bh_disable();
+	ret = __netif_rx(skb);
+	local_bh_enable();
 	return ret;
 }
 EXPORT_SYMBOL(netif_rx);
 
-int netif_rx_ni(struct sk_buff *skb)
-{
-	int err;
-
-	trace_netif_rx_ni_entry(skb);
-
-	preempt_disable();
-	err = netif_rx_internal(skb);
-	if (local_softirq_pending())
-		do_softirq();
-	preempt_enable();
-	trace_netif_rx_ni_exit(err);
-
-	return err;
-}
-EXPORT_SYMBOL(netif_rx_ni);
-
-int netif_rx_any_context(struct sk_buff *skb)
-{
-	/*
-	 * If invoked from contexts which do not invoke bottom half
-	 * processing either at return from interrupt or when softrqs are
-	 * reenabled, use netif_rx_ni() which invokes bottomhalf processing
-	 * directly.
-	 */
-	if (in_interrupt())
-		return netif_rx(skb);
-	else
-		return netif_rx_ni(skb);
-}
-EXPORT_SYMBOL(netif_rx_any_context);
-
 static __latent_entropy void net_tx_action(struct softirq_action *h)
 {
 	struct softnet_data *sd = this_cpu_ptr(&softnet_data);
@@ -5650,8 +5640,7 @@ static void flush_backlog(struct work_struct *work)
 	local_bh_disable();
 	sd = this_cpu_ptr(&softnet_data);
 
-	local_irq_disable();
-	rps_lock(sd);
+	rps_lock_irq_disable(sd);
 	skb_queue_walk_safe(&sd->input_pkt_queue, skb, tmp) {
 		if (skb->dev->reg_state == NETREG_UNREGISTERING) {
 			__skb_unlink(skb, &sd->input_pkt_queue);
@@ -5659,8 +5648,7 @@ static void flush_backlog(struct work_struct *work)
 			input_queue_head_incr(sd);
 		}
 	}
-	rps_unlock(sd);
-	local_irq_enable();
+	rps_unlock_irq_enable(sd);
 
 	skb_queue_walk_safe(&sd->process_queue, skb, tmp) {
 		if (skb->dev->reg_state == NETREG_UNREGISTERING) {
@@ -5678,16 +5666,14 @@ static bool flush_required(int cpu)
 	struct softnet_data *sd = &per_cpu(softnet_data, cpu);
 	bool do_flush;
 
-	local_irq_disable();
-	rps_lock(sd);
+	rps_lock_irq_disable(sd);
 
 	/* as insertion into process_queue happens with the rps lock held,
 	 * process_queue access may race only with dequeue
 	 */
 	do_flush = !skb_queue_empty(&sd->input_pkt_queue) ||
 		   !skb_queue_empty_lockless(&sd->process_queue);
-	rps_unlock(sd);
-	local_irq_enable();
+	rps_unlock_irq_enable(sd);
 
 	return do_flush;
 #endif
@@ -5757,12 +5743,14 @@ static void net_rps_action_and_irq_enable(struct softnet_data *sd)
 		sd->rps_ipi_list = NULL;
 
 		local_irq_enable();
+		preempt_check_resched_rt();
 
 		/* Send pending IPI's to kick RPS processing on remote cpus. */
 		net_rps_send_ipi(remsd);
 	} else
 #endif
 		local_irq_enable();
+	preempt_check_resched_rt();
 }
 
 static bool sd_has_rps_ipi_waiting(struct softnet_data *sd)
@@ -5802,8 +5790,7 @@ static int process_backlog(struct napi_struct *napi, int quota)
 
 		}
 
-		local_irq_disable();
-		rps_lock(sd);
+		rps_lock_irq_disable(sd);
 		if (skb_queue_empty(&sd->input_pkt_queue)) {
 			/*
 			 * Inline a custom version of __napi_complete().
@@ -5819,8 +5806,7 @@ static int process_backlog(struct napi_struct *napi, int quota)
 			skb_queue_splice_tail_init(&sd->input_pkt_queue,
 						   &sd->process_queue);
 		}
-		rps_unlock(sd);
-		local_irq_enable();
+		rps_unlock_irq_enable(sd);
 	}
 
 	return work;
@@ -5840,6 +5826,7 @@ void __napi_schedule(struct napi_struct *n)
 	local_irq_save(flags);
 	____napi_schedule(this_cpu_ptr(&softnet_data), n);
 	local_irq_restore(flags);
+	preempt_check_resched_rt();
 }
 EXPORT_SYMBOL(__napi_schedule);
 
@@ -10664,6 +10651,7 @@ static int dev_cpu_dead(unsigned int oldcpu)
 
 	raise_softirq_irqoff(NET_TX_SOFTIRQ);
 	local_irq_enable();
+	preempt_check_resched_rt();
 
 #ifdef CONFIG_RPS
 	remsd = oldsd->rps_ipi_list;
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index 30ab717ff1b81..17440840a7914 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -637,7 +637,9 @@ int __inet_hash(struct sock *sk, struct sock *osk)
 	int err = 0;
 
 	if (sk->sk_state != TCP_LISTEN) {
+		local_bh_disable();
 		inet_ehash_nolisten(sk, osk, NULL);
+		local_bh_enable();
 		return 0;
 	}
 	WARN_ON(!sk_unhashed(sk));
@@ -669,45 +671,54 @@ int inet_hash(struct sock *sk)
 {
 	int err = 0;
 
-	if (sk->sk_state != TCP_CLOSE) {
-		local_bh_disable();
+	if (sk->sk_state != TCP_CLOSE)
 		err = __inet_hash(sk, NULL);
-		local_bh_enable();
-	}
 
 	return err;
 }
 EXPORT_SYMBOL_GPL(inet_hash);
 
-void inet_unhash(struct sock *sk)
+static void __inet_unhash(struct sock *sk, struct inet_listen_hashbucket *ilb)
 {
-	struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
-	struct inet_listen_hashbucket *ilb = NULL;
-	spinlock_t *lock;
-
 	if (sk_unhashed(sk))
 		return;
 
-	if (sk->sk_state == TCP_LISTEN) {
-		ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
-		lock = &ilb->lock;
-	} else {
-		lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
-	}
-	spin_lock_bh(lock);
-	if (sk_unhashed(sk))
-		goto unlock;
-
 	if (rcu_access_pointer(sk->sk_reuseport_cb))
 		reuseport_stop_listen_sock(sk);
 	if (ilb) {
+		struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
+
 		inet_unhash2(hashinfo, sk);
 		ilb->count--;
 	}
 	__sk_nulls_del_node_init_rcu(sk);
 	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
-unlock:
-	spin_unlock_bh(lock);
+}
+
+void inet_unhash(struct sock *sk)
+{
+	struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
+
+	if (sk_unhashed(sk))
+		return;
+
+	if (sk->sk_state == TCP_LISTEN) {
+		struct inet_listen_hashbucket *ilb;
+
+		ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
+		/* Don't disable bottom halves while acquiring the lock to
+		 * avoid circular locking dependency on PREEMPT_RT.
+		 */
+		spin_lock(&ilb->lock);
+		__inet_unhash(sk, ilb);
+		spin_unlock(&ilb->lock);
+	} else {
+		spinlock_t *lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
+
+		spin_lock_bh(lock);
+		__inet_unhash(sk, NULL);
+		spin_unlock_bh(lock);
+	}
 }
 EXPORT_SYMBOL_GPL(inet_unhash);
 
diff --git a/net/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c
index 4514444e96c8d..4740afecf7c62 100644
--- a/net/ipv6/inet6_hashtables.c
+++ b/net/ipv6/inet6_hashtables.c
@@ -333,11 +333,8 @@ int inet6_hash(struct sock *sk)
 {
 	int err = 0;
 
-	if (sk->sk_state != TCP_CLOSE) {
-		local_bh_disable();
+	if (sk->sk_state != TCP_CLOSE)
 		err = __inet_hash(sk, NULL);
-		local_bh_enable();
-	}
 
 	return err;
 }
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index b21ad79941474..c2d04e9745dfe 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -440,7 +440,7 @@ void svc_xprt_do_enqueue(struct svc_xprt *xprt)
 	if (test_and_set_bit(XPT_BUSY, &xprt->xpt_flags))
 		return;
 
-	cpu = get_cpu();
+	cpu = get_cpu_light();
 	pool = svc_pool_for_cpu(xprt->xpt_server, cpu);
 
 	atomic_long_inc(&pool->sp_stats.packets);
@@ -464,7 +464,7 @@ void svc_xprt_do_enqueue(struct svc_xprt *xprt)
 	rqstp = NULL;
 out_unlock:
 	rcu_read_unlock();
-	put_cpu();
+	put_cpu_light();
 	trace_svc_xprt_enqueue(xprt, rqstp);
 }
 EXPORT_SYMBOL_GPL(svc_xprt_do_enqueue);
