[tip:sched/urgent] sched/fair: Fix the min_vruntime update logic in dequeue_entity()

From: tip-bot for Song Muchun
Date: Tue Oct 16 2018 - 05:16:20 EST


Commit-ID: 9845c49cc9bbb317a0bc9e9cf78d8e09d54c9af0
Gitweb: https://git.kernel.org/tip/9845c49cc9bbb317a0bc9e9cf78d8e09d54c9af0
Author: Song Muchun <smuchun@xxxxxxxxx>
AuthorDate: Sun, 14 Oct 2018 19:26:12 +0800
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 16 Oct 2018 09:36:01 +0200

sched/fair: Fix the min_vruntime update logic in dequeue_entity()

The comment and the code around the update_min_vruntime() call in
dequeue_entity() are not in agreement.

>From commit:

b60205c7c558 ("sched/fair: Fix min_vruntime tracking")

I think that we want to update min_vruntime when a task is sleeping/migrating.
So, the check is inverted there - fix it.

Signed-off-by: Song Muchun <smuchun@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Fixes: b60205c7c558 ("sched/fair: Fix min_vruntime tracking")
Link: http://lkml.kernel.org/r/20181014112612.2614-1-smuchun@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/sched/fair.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index f88e00705b55..908c9cdae2f0 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4001,7 +4001,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
* put back on, and if we advance min_vruntime, we'll be placed back
* further than we started -- ie. we'll be penalized.
*/
- if ((flags & (DEQUEUE_SAVE | DEQUEUE_MOVE)) == DEQUEUE_SAVE)
+ if ((flags & (DEQUEUE_SAVE | DEQUEUE_MOVE)) != DEQUEUE_SAVE)
update_min_vruntime(cfs_rq);
}