Commit-ID: 754bd598be9bbc953bc709a9e8ed7f3188bfb9d7 Gitweb: http://git.kernel.org/tip/754bd598be9bbc953bc709a9e8ed7f3188bfb9d7 Author: Konstantin Khlebnikov <[email protected]> AuthorDate: Thu, 16 Jun 2016 15:57:15 +0300 Committer: Ingo Molnar <[email protected]> CommitDate: Fri, 24 Jun 2016 08:26:45 +0200
sched/fair: Do not announce throttled next buddy in dequeue_task_fair() 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 <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Ben Segall <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: http://lkml.kernel.org/r/146608183552.21905.15924473394414832071.stgit@buzz Signed-off-by: Ingo Molnar <[email protected]> --- 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 8c5d8c0..bdcbeea 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4537,15 +4537,14 @@ 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;
