From: Konstantin Khlebnikov <khlebni...@yandex-team.ru> ms commit: 754bd598be9bbc953bc709a9e8ed7f3188bfb9d7.
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: Konstantin Khlebnikov <khlebni...@yandex-team.ru> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Reviewed-by: Ben Segall <bseg...@google.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Link: http://lkml.kernel.org/r/146608183552.21905.15924473394414832071.stgit@buzz Signed-off-by: Ingo Molnar <mi...@kernel.org> https://jira.sw.ru/browse/PSBM-50099 Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.com> --- kernel/sched/fair.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index b6f70a3..a87bacf 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4215,15 +4215,14 @@ 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; -- 2.7.3 _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel
