Patch "sched/fair: Do not announce throttled next buddy in dequeue_task_fair()" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

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

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
sched-fair-do-not-announce-throttled-next-buddy-in-dequeue_task_fair.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Konstantin Khlebnikov <[email protected]>
Date: Thu, 16 Jun 2016 15:57:15 +0300
Subject: sched/fair: Do not announce throttled next buddy in dequeue_task_fair()

From: Konstantin Khlebnikov <[email protected]>

commit 754bd598be9bbc953bc709a9e8ed7f3188bfb9d7 upstream.

Hierarchy could be already throttled at this point. Throttled next buddy could trigger a NULL pointer dereference in pick_next_task_fair().

---
 kernel/sched/fair.c |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

@@ -4233,15 +4233,14 @@ static void dequeue_task_fair(struct rq
 
 		/* 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;

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/sched-fair-do-not-announce-throttled-next-buddy-in-dequeue_task_fair.patch queue-4.4/sched-fair-initialize-throttle_count-for-new-task-groups-lazily.patch