John reported a DEBUG_PREEMPT warning caused by commit:
aacedf26fb76 ("sched/core: Optimize try_to_wake_up() for local wakeups")
I overlooked that ttwu_stat() requires preemption disabled.
Reported-by: John Stultz <john.stultz@linaro.org>
Tested-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes:
aacedf26fb76 ("sched/core: Optimize try_to_wake_up() for local wakeups")
Link: https://lkml.kernel.org/r/20190710105736.GK3402@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
unsigned long flags;
int cpu, success = 0;
+ preempt_disable();
if (p == current) {
/*
* We're waking current, this means 'p->on_rq' and 'task_cpu(p)
* it disabling IRQs (this allows not taking ->pi_lock).
*/
if (!(p->state & state))
- return false;
+ goto out;
success = 1;
cpu = task_cpu(p);
out:
if (success)
ttwu_stat(p, cpu, wake_flags);
+ preempt_enable();
return success;
}