Commit 0f665ed5 authored by Konstantin Khlebnikov's avatar Konstantin Khlebnikov Committed by Sasha Levin

sched/fair: Do not announce throttled next buddy in dequeue_task_fair()

[ Upstream commit 754bd598 ]

Hierarchy could be already throttled at this point. Throttled next
buddy could trigger a NULL pointer dereference in pick_next_task_fair().
Signed-off-by: default avatarKonstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarBen Segall <bsegall@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/146608183552.21905.15924473394414832071.stgit@buzzSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default avatarSasha Levin <alexander.levin@verizon.com>
parent 953334de
...@@ -4290,15 +4290,14 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) ...@@ -4290,15 +4290,14 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
/* Don't dequeue parent if it has other entities besides us */ /* Don't dequeue parent if it has other entities besides us */
if (cfs_rq->load.weight) { if (cfs_rq->load.weight) {
/* Avoid re-evaluating load for this entity: */
se = parent_entity(se);
/* /*
* Bias pick_next to pick a task from this cfs_rq, as * Bias pick_next to pick a task from this cfs_rq, as
* p is sleeping when it is within its sched_slice. * p is sleeping when it is within its sched_slice.
*/ */
if (task_sleep && parent_entity(se)) if (task_sleep && se && !throttled_hierarchy(cfs_rq))
set_next_buddy(parent_entity(se)); set_next_buddy(se);
/* avoid re-evaluating load for this entity */
se = parent_entity(se);
break; break;
} }
flags |= DEQUEUE_SLEEP; flags |= DEQUEUE_SLEEP;
......
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