linux-kernel - Re: [PATCH v9 06/20] cpuset: Don't use the cpu_possible

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Message-ID: <878s3hdgea.mognet@arm.com>
Date:   Thu, 10 Jun 2021 13:59:41 +0100
From:   Valentin Schneider <valentin.schneider@....com>
To:     Will Deacon <will@...nel.org>, linux-arm-kernel@...ts.infradead.org
Cc:     linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
        Will Deacon <will@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Marc Zyngier <maz@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Qais Yousef <qais.yousef@....com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Quentin Perret <qperret@...gle.com>, Tejun Heo <tj@...nel.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Ingo Molnar <mingo@...hat.com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Mark Rutland <mark.rutland@....com>, kernel-team@...roid.com
Subject: Re: [PATCH v9 06/20] cpuset: Don't use the cpu_possible_mask as a last resort for cgroup v1

On 08/06/21 19:02, Will Deacon wrote:
> If the scheduler cannot find an allowed CPU for a task,
> cpuset_cpus_allowed_fallback() will widen the affinity to cpu_possible_mask
> if cgroup v1 is in use.
>
> In preparation for allowing architectures to provide their own fallback
> mask, just return early if we're either using cgroup v1 or we're using
> cgroup v2 with a mask that contains invalid CPUs. This will allow
> select_fallback_rq() to figure out the mask by itself.
>
> Cc: Tejun Heo <tj@...nel.org>
> Cc: Johannes Weiner <hannes@...xchg.org>
> Reviewed-by: Quentin Perret <qperret@...gle.com>
> Signed-off-by: Will Deacon <will@...nel.org>

Reviewed-by: Valentin Schneider <valentin.schneider@....com>