Commit f01ae9cb authored by Konstantin Khlebnikov's avatar Konstantin Khlebnikov Committed by Greg Kroah-Hartman

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

commit 754bd598 upstream.

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>
Cc: Ben Pineau <benjamin.pineau@mirakl.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ae3d7b89
......@@ -4233,15 +4233,14 @@ 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 */
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
* p is sleeping when it is within its sched_slice.
*/
if (task_sleep && parent_entity(se))
set_next_buddy(parent_entity(se));
/* avoid re-evaluating load for this entity */
se = parent_entity(se);
if (task_sleep && se && !throttled_hierarchy(cfs_rq))
set_next_buddy(se);
break;
}
flags |= DEQUEUE_SLEEP;
......
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