linux-kernel - [PATCH] sched/fair: Fix se_is_idle() for !FAIR_GROUP

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Date:   Wed,  8 Sep 2021 16:39:46 -0400
From:   Daniel Jordan <daniel.m.jordan@...cle.com>
To:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        Daniel Bristot de Oliveira <bristot@...hat.com>
Cc:     Josh Don <joshdon@...gle.com>, linux-kernel@...r.kernel.org,
        Daniel Jordan <daniel.m.jordan@...cle.com>
Subject: [PATCH] sched/fair: Fix se_is_idle() for !FAIR_GROUP_SCHED

se_is_idle() unconditionally returns 0 for !FAIR_GROUP_SCHED.

Check whether the task is SCHED_IDLE instead so buddies aren't set for
such tasks, as was the behavior before 304000390f88.

Fixes: 304000390f88 ("sched: Cgroup SCHED_IDLE support")
Signed-off-by: Daniel Jordan <daniel.m.jordan@...cle.com>
---
 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 ff69f245b939..8b22665bc18e 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -497,7 +497,7 @@ static int cfs_rq_is_idle(struct cfs_rq *cfs_rq)
 
 static int se_is_idle(struct sched_entity *se)
 {
-	return 0;
+	return task_has_idle_policy(task_of(se));
 }
 
 #endif	/* CONFIG_FAIR_GROUP_SCHED */

base-commit: ac08b1c68d1b1ed3cebb218fc3ea2c07484eb07d
-- 
2.32.0