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

Song Muchun · Ingo Molnar · commit 9845c49cc9bb · 2018-10-16T09:36:01.000+02:00
The comment and the code around the update_min_vruntime() call in dequeue_entity() are not in agreement. From commit: b60205c ("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@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: b60205c ("sched/fair: Fix min_vruntime tracking") Link: http://lkml.kernel.org/r/20181014112612.2614-1-smuchun@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git 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);
 }
 

Original file line number	Diff line number	Diff line change
`@@ -4001,7 +4001,7 @@ dequeue_entity(struct cfs_rq cfs_rq, struct sched_entity se, int flags)`
`4001`	`4001`	`* put back on, and if we advance min_vruntime, we'll be placed back`
`4002`	`4002`	`* further than we started -- ie. we'll be penalized.`
`4003`	`4003`	`*/`
`4004`		`- if ((flags & (DEQUEUE_SAVE \| DEQUEUE_MOVE)) == DEQUEUE_SAVE)`
	`4004`	`+ if ((flags & (DEQUEUE_SAVE \| DEQUEUE_MOVE)) != DEQUEUE_SAVE)`
`4005`	`4005`	`update_min_vruntime(cfs_rq);`
`4006`	`4006`	`}`
`4007`	`4007`