linux-kernel - Re: [PATCH v11 7/8] cgroup/cpuset: Update description of cpuset.cpus.partition in cgroup-v2.rst

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Date:   Tue, 14 Jun 2022 13:53:45 +0200
From:   Michal Koutný <mkoutny@...e.com>
To:     Tejun Heo <tj@...nel.org>
Cc:     Waiman Long <longman@...hat.com>,
        Zefan Li <lizefan.x@...edance.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Jonathan Corbet <corbet@....net>,
        Shuah Khan <shuah@...nel.org>, cgroups@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-kselftest@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Roman Gushchin <guro@...com>, Phil Auld <pauld@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Frederic Weisbecker <frederic@...nel.org>,
        Marcelo Tosatti <mtosatti@...hat.com>
Subject: Re: [PATCH v11 7/8] cgroup/cpuset: Update description of
 cpuset.cpus.partition in cgroup-v2.rst

On Mon, Jun 13, 2022 at 08:00:56AM -1000, Tejun Heo <tj@...nel.org> wrote:
> Yeah, I don't know why this part is different from any other errors that the
> parent can make.

It's different because a write to parent's cpuset.cpus is independent of
whether cpuset.cpus of its children are exclusive or not.
In an extreme case the children may be non-exclusive

    parent	cpuset.cpus=0-3 //   valid partition
    `- child_1	cpuset.cpus=0-1	// invalid partition
    `- child_2	cpuset.cpus=1-2 // invalid partition

but the parent can still be a valid partition (thanks to cpu no. 3 in
the example above).

Do I miss anything?

Thanks,
Michal

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