sched/core: Idle_task_exit() shouldn't use switch_mm_irqs_off()

[karo-tx-linux.git] / kernel / sched / core.c

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 759f4bd52cd6b3724b858d41f57ff305a3747c8b..326d4f88e2b1dbda470c7730c6ae1a67cc095f99 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3502,6 +3502,31 @@ asmlinkage __visible void __sched schedule(void)
 }
 EXPORT_SYMBOL(schedule);
 
+/*
+ * synchronize_rcu_tasks() makes sure that no task is stuck in preempted
+ * state (have scheduled out non-voluntarily) by making sure that all
+ * tasks have either left the run queue or have gone into user space.
+ * As idle tasks do not do either, they must not ever be preempted
+ * (schedule out non-voluntarily).
+ *
+ * schedule_idle() is similar to schedule_preempt_disable() except that it
+ * never enables preemption because it does not call sched_submit_work().
+ */
+void __sched schedule_idle(void)
+{
+       /*
+        * As this skips calling sched_submit_work(), which the idle task does
+        * regardless because that function is a nop when the task is in a
+        * TASK_RUNNING state, make sure this isn't used someplace that the
+        * current task can be in any other state. Note, idle is always in the
+        * TASK_RUNNING state.
+        */
+       WARN_ON_ONCE(current->state);
+       do {
+               __schedule(false);
+       } while (need_resched());
+}
+
 #ifdef CONFIG_CONTEXT_TRACKING
 asmlinkage __visible void __sched schedule_user(void)
 {
@@ -5580,7 +5605,7 @@ void idle_task_exit(void)
        BUG_ON(cpu_online(smp_processor_id()));
 
        if (mm != &init_mm) {
-               switch_mm_irqs_off(mm, &init_mm, current);
+               switch_mm(mm, &init_mm, current);
                finish_arch_post_lock_switch();
        }
        mmdrop(mm);