Index: linux-stable/include/linux/sched.h
===================================================================
--- linux-stable.orig/include/linux/sched.h
+++ linux-stable/include/linux/sched.h
@@ -2144,6 +2144,7 @@ extern unsigned int sysctl_sched_cfs_ban
 #ifdef CONFIG_RT_MUTEXES
 extern int rt_mutex_getprio(struct task_struct *p);
 extern void rt_mutex_setprio(struct task_struct *p, int prio);
+extern int rt_mutex_check_prio(struct task_struct *task, int newprio);
 extern void rt_mutex_adjust_pi(struct task_struct *p);
 static inline bool tsk_is_pi_blocked(struct task_struct *tsk)
 {
@@ -2154,6 +2155,10 @@ static inline int rt_mutex_getprio(struc
 {
 	return p->normal_prio;
 }
+static inline int rt_mutex_check_prio(struct task_struct *task, int newprio)
+{
+	return 0;
+}
 # define rt_mutex_adjust_pi(p)		do { } while (0)
 static inline bool tsk_is_pi_blocked(struct task_struct *tsk)
 {
Index: linux-stable/kernel/rtmutex.c
===================================================================
--- linux-stable.orig/kernel/rtmutex.c
+++ linux-stable/kernel/rtmutex.c
@@ -124,6 +124,18 @@ int rt_mutex_getprio(struct task_struct 
 }
 
 /*
+ * Called by sched_setscheduler() to check whether the priority change
+ * is overruled by a possible priority boosting.
+ */
+int rt_mutex_check_prio(struct task_struct *task, int newprio)
+{
+	if (!task_has_pi_waiters(task))
+		return 0;
+
+	return task_top_pi_waiter(task)->pi_list_entry.prio <= newprio;
+}
+
+/*
  * Adjust the priority of a task, after its pi_waiters got modified.
  *
  * This can be both boosting and unboosting. task->pi_lock must be held.
Index: linux-stable/kernel/sched/core.c
===================================================================
--- linux-stable.orig/kernel/sched/core.c
+++ linux-stable/kernel/sched/core.c
@@ -4236,7 +4236,8 @@ EXPORT_SYMBOL(sleep_on_timeout);
  * This function changes the 'effective' priority of a task. It does
  * not touch ->normal_prio like __setscheduler().
  *
- * Used by the rt_mutex code to implement priority inheritance logic.
+ * Used by the rt_mutex code to implement priority inheritance
+ * logic. Call site only calls if the priority of the task changed.
  */
 void rt_mutex_setprio(struct task_struct *p, int prio)
 {
@@ -4268,8 +4269,6 @@ void rt_mutex_setprio(struct task_struct
 
 	trace_sched_pi_setprio(p, prio);
 	oldprio = p->prio;
-	if (oldprio == prio)
-		goto out_unlock;
 	prev_class = p->sched_class;
 	on_rq = p->on_rq;
 	running = task_current(rq, p);
@@ -4461,20 +4460,25 @@ static struct task_struct *find_process_
 	return pid ? find_task_by_vpid(pid) : current;
 }
 
-/* Actually do priority change: must hold rq lock. */
-static void
-__setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio)
+static void __setscheduler_params(struct task_struct *p, int policy, int prio)
 {
 	p->policy = policy;
 	p->rt_priority = prio;
 	p->normal_prio = normal_prio(p);
+	set_load_weight(p);
+}
+
+/* Actually do priority change: must hold rq lock. */
+static void
+__setscheduler(struct rq *rq, struct task_struct *p, int policy, int prio)
+{
+	__setscheduler_params(p, policy, prio);
 	/* we are holding p->pi_lock already */
 	p->prio = rt_mutex_getprio(p);
 	if (rt_prio(p->prio))
 		p->sched_class = &rt_sched_class;
 	else
 		p->sched_class = &fair_sched_class;
-	set_load_weight(p);
 }
 
 /*
@@ -4496,6 +4500,7 @@ static bool check_same_owner(struct task
 static int __sched_setscheduler(struct task_struct *p, int policy,
 				const struct sched_param *param, bool user)
 {
+	int newprio = MAX_RT_PRIO - 1 - param->sched_priority;
 	int retval, oldprio, oldpolicy = -1, on_rq, running;
 	unsigned long flags;
 	const struct sched_class *prev_class;
@@ -4591,10 +4596,13 @@ recheck:
 	}
 
 	/*
-	 * If not changing anything there's no need to proceed further:
+	 * If not changing anything there's no need to proceed
+	 * further, but store a possible modification of
+	 * reset_on_fork.
 	 */
 	if (unlikely(policy == p->policy && (!rt_policy(policy) ||
 			param->sched_priority == p->rt_priority))) {
+		p->sched_reset_on_fork = reset_on_fork;
 		task_rq_unlock(rq, p, &flags);
 		return 0;
 	}
@@ -4622,10 +4630,22 @@ recheck:
 	}
 
 	p->sched_reset_on_fork = reset_on_fork;
-
 	oldprio = p->prio;
-	if (oldprio == param->sched_priority)
-		goto out;
+
+	/*
+	 * Special case for priority boosted tasks.
+	 *
+	 * If the new priority is lower or equal (user space view)
+	 * than the current (boosted) priority, we just store the new
+	 * normal parameters and do not touch the scheduler class and
+	 * the runqueue. This will be done when the task deboost
+	 * itself.
+	 */
+	if (rt_mutex_check_prio(p, newprio)) {
+		__setscheduler_params(p, policy, param->sched_priority);
+		task_rq_unlock(rq, p, &flags);
+		return 0;
+	}
 
 	on_rq = p->on_rq;
 	running = task_current(rq, p);
@@ -4639,12 +4659,14 @@ recheck:
 
 	if (running)
 		p->sched_class->set_curr_task(rq);
-	if (on_rq)
-		enqueue_task(rq, p, oldprio < param->sched_priority ?
-			     ENQUEUE_HEAD : 0);
-
+	if (on_rq) {
+		/*
+		 * We enqueue to tail when the priority of a task is
+		 * increased (user space view).
+		 */
+		enqueue_task(rq, p, oldprio <= p->prio ? ENQUEUE_HEAD : 0);
+	}
 	check_class_changed(rq, p, prev_class, oldprio);
-out:
 	task_rq_unlock(rq, p, &flags);
 
 	rt_mutex_adjust_pi(p);
Index: linux-stable/localversion-rt
===================================================================
--- linux-stable.orig/localversion-rt
+++ linux-stable/localversion-rt
@@ -1 +1 @@
--rt23
+-rt24
Index: linux-stable/block/blk-ioc.c
===================================================================
--- linux-stable.orig/block/blk-ioc.c
+++ linux-stable/block/blk-ioc.c
@@ -110,7 +110,7 @@ static void ioc_release_fn(struct work_s
 			spin_unlock(q->queue_lock);
 		} else {
 			spin_unlock_irqrestore(&ioc->lock, flags);
-			cpu_relax();
+			cpu_chill();
 			spin_lock_irqsave_nested(&ioc->lock, flags, 1);
 		}
 	}
@@ -188,7 +188,7 @@ retry:
 			spin_unlock(icq->q->queue_lock);
 		} else {
 			spin_unlock_irqrestore(&ioc->lock, flags);
-			cpu_relax();
+			cpu_chill();
 			goto retry;
 		}
 	}
