[GIT PULL] scheduler fix

From: Ingo Molnar
Date: Sun Jul 14 2019 - 06:19:19 EST


Linus,

Please pull the latest sched-urgent-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched-urgent-for-linus

# HEAD: e3d85487fba42206024bc3ed32e4b581c7cb46db sched/core: Fix preempt warning in ttwu

Fix a sched statistics related bug that would trigger a kernel warning on
certain configs.

Thanks,

Ingo

------------------>
Peter Zijlstra (1):
sched/core: Fix preempt warning in ttwu


kernel/sched/core.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index fa43ce3962e7..2b037f195473 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2399,6 +2399,7 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
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)
@@ -2412,7 +2413,7 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
* it disabling IRQs (this allows not taking ->pi_lock).
*/
if (!(p->state & state))
- return false;
+ goto out;

success = 1;
cpu = task_cpu(p);
@@ -2526,6 +2527,7 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
out:
if (success)
ttwu_stat(p, cpu, wake_flags);
+ preempt_enable();

return success;
}