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From:   Josh Don <joshdon@google.com>
Date:   Wed, 8 Sep 2021 13:56:01 -0700
Message-ID: <CABk29Nv3_nu_5QqHriTw1PXVywSvwF1Ds0+JWos3avLbn+OVQA@mail.gmail.com>
Subject: Re: [PATCH] sched/fair: Fix se_is_idle() for !FAIR_GROUP_SCHED
To:     Daniel Jordan <daniel.m.jordan@oracle.com>
Cc:     Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
        Daniel Bristot de Oliveira <bristot@redhat.com>,
        linux-kernel <linux-kernel@vger.kernel.org>
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On Wed, Sep 8, 2021 at 1:40 PM Daniel Jordan <daniel.m.jordan@oracle.com> wrote:
>
> 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@oracle.com>

Thanks!

Reviewed-by: Josh Don <joshdon@google.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
>