Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20210908203946.1261798-1-daniel.m.jordan@oracle.com>
In-Reply-To: <20210908203946.1261798-1-daniel.m.jordan@oracle.com>
From:   Vincent Guittot <vincent.guittot@linaro.org>
Date:   Thu, 9 Sep 2021 08:48:53 +0200
Message-ID: <CAKfTPtArYGHgEaa3GEMeJWzk_n4BDk1SanjrDU_-3fn=okrDEg@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>,
        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>,
        Josh Don <joshdon@google.com>,
        linux-kernel <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Wed, 8 Sept 2021 at 22:40, 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>

Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>

> ---
>  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
>