[patch 01/15] sched: (fixlet) dont update shares twice on on_rq parent

[Paul Turner <pjt@google.com>]

[-- Attachment #1: sched-bwc-fix_dequeue_task_buglet.patch --]
[-- Type: text/plain, Size: 947 bytes --]

In dequeue_task_fair() we bail on dequeue when we encounter a parenting entity
with additional weight.  However, we perform a double shares update on this
entity since we continue the shares update traversal from that point, despite
dequeue_entity() having already updated its queuing cfs_rq.

Avoid this by starting from the parent when we resume.

Signed-off-by: Paul Turner <pjt@google.com>
---
 kernel/sched_fair.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Index: tip/kernel/sched_fair.c
===================================================================
--- tip.orig/kernel/sched_fair.c
+++ tip/kernel/sched_fair.c
@@ -1355,8 +1355,10 @@ static void dequeue_task_fair(struct rq 
 		dequeue_entity(cfs_rq, se, flags);
 
 		/* Don't dequeue parent if it has other entities besides us */
-		if (cfs_rq->load.weight)
+		if (cfs_rq->load.weight) {
+			se = parent_entity(se);
 			break;
+		}
 		flags |= DEQUEUE_SLEEP;
 	}