[patch 01/17] 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: 898 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 as we continue the shares update traversal from this 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 |    3 +++
 1 file changed, 3 insertions(+)

Index: tip/kernel/sched_fair.c
===================================================================
--- tip.orig/kernel/sched_fair.c
+++ tip/kernel/sched_fair.c
@@ -1370,6 +1370,9 @@ static void dequeue_task_fair(struct rq 
 			 */
 			if (task_sleep && parent_entity(se))
 				set_next_buddy(parent_entity(se));
+
+			/* avoid re-evaluating load for this entity */
+			se = parent_entity(se);
 			break;
 		}
 		flags |= DEQUEUE_SLEEP;