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[patch 17/18] sched: Enable might_sleep() checks early

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might_sleep() checks are enabled after the boot process is done. That hides
bugs in the smp bringup and driver initialization code.

Enable it right when the scheduler starts working, i.e. when init task and
kthreadd have been created and right before the idle task enables
preemption.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 init/main.c         |    2 ++
 kernel/sched/core.c |    4 +++-
 2 files changed, 5 insertions(+), 1 deletion(-)

--- a/init/main.c
+++ b/init/main.c
@@ -410,6 +410,8 @@ static noinline void __ref rest_init(voi
 	 * at least once to get things moving:
 	 */
 	init_idle_bootup_task(current);
+	/* Enable might_sleep() checks */
+	system_state = SYSTEM_BOOTING_UP;
 	schedule_preempt_disabled();
 	/* Call into cpu_idle with preempt disabled */
 	cpu_startup_entry(CPUHP_ONLINE);
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6226,8 +6226,10 @@ void ___might_sleep(const char *file, in
 
 	if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
 	     !is_idle_task(current)) ||
-	    system_state != SYSTEM_RUNNING || oops_in_progress)
+	    system_state == SYSTEM_BOOTING || system_state > SYSTEM_RUNNING ||
+	    oops_in_progress)
 		return;
+
 	if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
 		return;
 	prev_jiffy = jiffies;

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[patch 17/18] sched: Enable might_sleep() checks early Thomas Gleixner <tglx@linutronix.de> - 2017-05-14 20:40 +0200
  Re: [patch 17/18] sched: Enable might_sleep() checks early Steven Rostedt <rostedt@goodmis.org> - 2017-05-15 17:20 +0200
    Re: [patch 17/18] sched: Enable might_sleep() checks early Thomas Gleixner <tglx@linutronix.de> - 2017-05-15 21:20 +0200
      Re: [patch 17/18] sched: Enable might_sleep() checks early Peter Zijlstra <peterz@infradead.org> - 2017-05-16 09:20 +0200
        Re: [patch 17/18] sched: Enable might_sleep() checks early Thomas Gleixner <tglx@linutronix.de> - 2017-05-16 09:40 +0200
          Re: [patch 17/18] sched: Enable might_sleep() checks early Steven Rostedt <rostedt@goodmis.org> - 2017-05-16 15:20 +0200

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