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Date:   Mon, 13 Jun 2022 12:47:37 -0400
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Subject: Re: [PATCH v11 3/8] cgroup/cpuset: Allow no-task partition to have
 empty cpuset.cpus.effective
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To:     =?UTF-8?Q?Michal_Koutn=c3=bd?= <mkoutny@suse.com>,
        Tejun Heo <tj@kernel.org>
Cc:     Zefan Li <lizefan.x@bytedance.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Shuah Khan <shuah@kernel.org>, cgroups@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-kselftest@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Roman Gushchin <guro@fb.com>, Phil Auld <pauld@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Juri Lelli <juri.lelli@redhat.com>,
        Frederic Weisbecker <frederic@kernel.org>,
        Marcelo Tosatti <mtosatti@redhat.com>
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From:   Waiman Long <longman@redhat.com>
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On 6/13/22 10:02, Michal Koutný wrote:
> On Sun, Jun 12, 2022 at 04:55:13PM -1000, Tejun Heo <tj@kernel.org> wrote:
>> But how would that happen? A lot of other things would break too if that
>> were to happen.
> cpuset is a threaded controller where the internal-node-constraint does
> not hold. So the additional condition for cpuset migrations is IMO
> warranted (and needed if there's no "fall up").

Yes, you are right. cpuset is threaded and so it may have tasks even if 
it is not the leaf node.

Thanks,
Longman