3 files changed, 41 insertions, 17 deletions

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index df00cb09263e..5255c9d2e053 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -74,6 +74,7 @@
 
 #include <asm/tlb.h>
 #include <asm/irq_regs.h>
+#include <asm/mutex.h>
 #ifdef CONFIG_PARAVIRT
 #include <asm/paravirt.h>
 #endif
@@ -723,9 +724,6 @@ static void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
         p->sched_class->dequeue_task(rq, p, flags);
 }
 
-/*
- * activate_task - move a task to the runqueue.
- */
 void activate_task(struct rq *rq, struct task_struct *p, int flags)
 {
         if (task_contributes_to_load(p))
@@ -734,9 +732,6 @@ void activate_task(struct rq *rq, struct task_struct *p, int flags)
         enqueue_task(rq, p, flags);
 }
 
-/*
- * deactivate_task - remove a task from the runqueue.
- */
 void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
 {
         if (task_contributes_to_load(p))
@@ -4134,7 +4129,7 @@ recheck:
         on_rq = p->on_rq;
         running = task_current(rq, p);
         if (on_rq)
-                deactivate_task(rq, p, 0);
+                dequeue_task(rq, p, 0);
         if (running)
                 p->sched_class->put_prev_task(rq, p);
 
@@ -4147,7 +4142,7 @@ recheck:
         if (running)
                 p->sched_class->set_curr_task(rq);
         if (on_rq)
-                activate_task(rq, p, 0);
+                enqueue_task(rq, p, 0);
 
         check_class_changed(rq, p, prev_class, oldprio);
         task_rq_unlock(rq, p, &flags);
@@ -4998,9 +4993,9 @@ static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
          * placed properly.
          */
         if (p->on_rq) {
-                deactivate_task(rq_src, p, 0);
+                dequeue_task(rq_src, p, 0);
                 set_task_cpu(p, dest_cpu);
-                activate_task(rq_dest, p, 0);
+                enqueue_task(rq_dest, p, 0);
                 check_preempt_curr(rq_dest, p, 0);
         }
 done:
@@ -7032,10 +7027,10 @@ static void normalize_task(struct rq *rq, struct task_struct *p)
 
         on_rq = p->on_rq;
         if (on_rq)
-                deactivate_task(rq, p, 0);
+                dequeue_task(rq, p, 0);
         __setscheduler(rq, p, SCHED_NORMAL, 0);
         if (on_rq) {
-                activate_task(rq, p, 0);
+                enqueue_task(rq, p, 0);
                 resched_task(rq->curr);
         }
 
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 84adb2d66cbd..7c6414fc669d 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4866,6 +4866,15 @@ static void nohz_balancer_kick(int cpu)
         return;
 }
 
+static inline void clear_nohz_tick_stopped(int cpu)
+{
+        if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) {
+                cpumask_clear_cpu(cpu, nohz.idle_cpus_mask);
+                atomic_dec(&nohz.nr_cpus);
+                clear_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
+        }
+}
+
 static inline void set_cpu_sd_state_busy(void)
 {
         struct sched_domain *sd;
@@ -4904,6 +4913,12 @@ void select_nohz_load_balancer(int stop_tick)
 {
         int cpu = smp_processor_id();
 
+        /*
+         * If this cpu is going down, then nothing needs to be done.
+         */
+        if (!cpu_active(cpu))
+                return;
+
         if (stop_tick) {
                 if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))
                         return;
@@ -4914,6 +4929,18 @@ void select_nohz_load_balancer(int stop_tick)
         }
         return;
 }
+
+static int __cpuinit sched_ilb_notifier(struct notifier_block *nfb,
+                                        unsigned long action, void *hcpu)
+{
+        switch (action & ~CPU_TASKS_FROZEN) {
+        case CPU_DYING:
+                clear_nohz_tick_stopped(smp_processor_id());
+                return NOTIFY_OK;
+        default:
+                return NOTIFY_DONE;
+        }
+}
 #endif
 
 static DEFINE_SPINLOCK(balancing);
@@ -5070,11 +5097,7 @@ static inline int nohz_kick_needed(struct rq *rq, int cpu)
         * busy tick after returning from idle, we will update the busy stats.
         */
         set_cpu_sd_state_busy();
-        if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) {
-                clear_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
-                cpumask_clear_cpu(cpu, nohz.idle_cpus_mask);
-                atomic_dec(&nohz.nr_cpus);
-        }
+        clear_nohz_tick_stopped(cpu);
 
         /*
          * None are in tickless mode and hence no need for NOHZ idle load
@@ -5590,6 +5613,7 @@ __init void init_sched_fair_class(void)
 
 #ifdef CONFIG_NO_HZ
         zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT);
+        cpu_notifier(sched_ilb_notifier, 0);
 #endif
 #endif /* SMP */
 
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 3640ebbb466b..f42ae7fb5ec5 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1587,6 +1587,11 @@ static int push_rt_task(struct rq *rq)
         if (!next_task)
                 return 0;
 
+#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
+       if (unlikely(task_running(rq, next_task)))
+               return 0;
+#endif
+
 retry:
         if (unlikely(next_task == rq->curr)) {
                 WARN_ON(1);