linux-kernel - Re: [PATCH 1/3] cgroup/cpuset: Make cpuset_fork() handle CLONE_INTO

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Message-ID: <a115f40d-057e-a4a9-474f-fb3dcf04edee@redhat.com>
Date:   Thu, 6 Apr 2023 10:08:31 -0400
From:   Waiman Long <longman@...hat.com>
To:     Christian Brauner <brauner@...nel.org>
Cc:     Tejun Heo <tj@...nel.org>, Zefan Li <lizefan.x@...edance.com>,
        Johannes Weiner <hannes@...xchg.org>, cgroups@...r.kernel.org,
        linux-kernel@...r.kernel.org, Juri Lelli <juri.lelli@...hat.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        gscrivan@...hat.com
Subject: Re: [PATCH 1/3] cgroup/cpuset: Make cpuset_fork() handle
 CLONE_INTO_CGROUP properly

On 4/6/23 05:45, Christian Brauner wrote:
> On Fri, Mar 31, 2023 at 10:50:43AM -0400, Waiman Long wrote:
>> By default, the clone(2) syscall spawn a child process into the same
>> cgroup as its parent. With the use of the CLONE_INTO_CGROUP flag
>> introduced by commit ef2c41cf38a7 ("clone3: allow spawning processes
>> into cgroups"), the child will be spawned into a different cgroup which
>> is somewhat similar to writing the child's tid into "cgroup.threads".
>>
>> The current cpuset_fork() method does not properly handle the
>> CLONE_INTO_CGROUP case where the cpuset of the child may be different
>> from that of its parent.  Update the cpuset_fork() method to treat the
>> CLONE_INTO_CGROUP case similar to cpuset_attach().
>>
>> Since the newly cloned task has not been running yet, its actual
>> memory usage isn't known. So it is not necessary to make change to mm
>> in cpuset_fork().
>>
>> Fixes: ef2c41cf38a7 ("clone3: allow spawning processes into cgroups")
>> Signed-off-by: Waiman Long <longman@...hat.com>
>> ---
> Just two nits. I think this needs a Cc stable and it would be nice if
> you could give Giuseppe a "Reported-by".

The presence of a fixes tag should make this patch picked up by stable. 
Yes, I will cc stable when I need to update the patch next time.

Right, I should have added

Reported-by: Giuseppe Scrivano <gscrivan@...hat.com>

Cheers,
Longman