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authorLinus Torvalds <torvalds@linux-foundation.org>2015-09-27 12:50:27 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2015-09-27 12:50:27 -0400
commit73f479b243fe71a0fa82d21a21ac25d8932b88d5 (patch)
tree939b9dfb73bf2efbd36bc4fb621603c822096fe2 /kernel
parentfc11a9c5dad78d2c9e8a4b7d4b386bff724d9ec3 (diff)
parentde9b8f5dcbd94bfb1d249907a635f1fb1968e19c (diff)
downloadlinux-73f479b243fe71a0fa82d21a21ac25d8932b88d5.tar.gz
Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fix from Thomas Gleixner:
 "A single bug fix for the scheduler to prevent dequeueing of the idle
  task when setting the cpus allowed mask"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched: Fix crash trying to dequeue/enqueue the idle thread
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/core.c14
1 files changed, 11 insertions, 3 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 2f9c92884817..615953141951 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4934,7 +4934,15 @@ void init_idle(struct task_struct *idle, int cpu)
 	idle->state = TASK_RUNNING;
 	idle->se.exec_start = sched_clock();
 
-	do_set_cpus_allowed(idle, cpumask_of(cpu));
+#ifdef CONFIG_SMP
+	/*
+	 * Its possible that init_idle() gets called multiple times on a task,
+	 * in that case do_set_cpus_allowed() will not do the right thing.
+	 *
+	 * And since this is boot we can forgo the serialization.
+	 */
+	set_cpus_allowed_common(idle, cpumask_of(cpu));
+#endif
 	/*
 	 * We're having a chicken and egg problem, even though we are
 	 * holding rq->lock, the cpu isn't yet set to this cpu so the
@@ -4951,7 +4959,7 @@ void init_idle(struct task_struct *idle, int cpu)
 
 	rq->curr = rq->idle = idle;
 	idle->on_rq = TASK_ON_RQ_QUEUED;
-#if defined(CONFIG_SMP)
+#ifdef CONFIG_SMP
 	idle->on_cpu = 1;
 #endif
 	raw_spin_unlock(&rq->lock);
@@ -4966,7 +4974,7 @@ void init_idle(struct task_struct *idle, int cpu)
 	idle->sched_class = &idle_sched_class;
 	ftrace_graph_init_idle_task(idle, cpu);
 	vtime_init_idle(idle, cpu);
-#if defined(CONFIG_SMP)
+#ifdef CONFIG_SMP
 	sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
 #endif
 }