Commit-ID: 754bd598be9bbc953bc709a9e8ed7f3188bfb9d7
Gitweb: http://git.kernel.org/tip/754bd598be9bbc953bc709a9e8ed7f3188bfb9d7
Author: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
AuthorDate: Thu, 16 Jun 2016 15:57:15 +0300
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
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 <khlebnikov@xxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Ben Segall <bsegall@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/146608183552.21905.15924473394414832071.stgit@buzz
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
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;
--
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