Re: mm, oom_reaper: How to handle race with oom_killer_disable() ?

From	Michal Hocko <mhocko@kernel.org>
Newsgroups	linux.kernel
Subject	Re: mm, oom_reaper: How to handle race with oom_killer_disable() ?
Date	2016-06-21 20:00 +0200
Message-ID	<rMy7T-xD-3@gated-at.bofh.it> (permalink)
References	(1 earlier) <rMpnY-3mT-43@gated-at.bofh.it> <rMslR-5hj-55@gated-at.bofh.it> <rMslR-5hj-53@gated-at.bofh.it> <rMtUC-6nL-7@gated-at.bofh.it> <rMvWq-7DO-23@gated-at.bofh.it>
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On Wed 22-06-16 00:32:29, Tetsuo Handa wrote:
> Michal Hocko wrote:
[...]
> > Hmm, what about the following instead. It is rather a workaround than a
> > full flaged fix but it seems much more easier and shouldn't introduce
> > new issues.
> 
> Yes, I think that will work. But I think below patch (marking signal_struct
> to ignore TIF_MEMDIE instead of clearing TIF_MEMDIE from task_struct) on top of
> current linux.git will implement no-lockup requirement. No race is possible unlike
> "[PATCH 10/10] mm, oom: hide mm which is shared with kthread or global init".

Not really. Because without the exit_oom_victim from oom_reaper you have
no guarantee that the oom_killer_disable will ever return. I have
mentioned that in the changelog. There is simply no guarantee the oom
victim will ever reach exit_mm->exit_oom_victim.
-- 
Michal Hocko
SUSE Labs

Thread

Re: mm, oom_reaper: How to handle race with oom_killer_disable() ? Michal Hocko <mhocko@kernel.org> - 2016-06-13 13:20 +0200
  Re: mm, oom_reaper: How to handle race with oom_killer_disable() ? Michal Hocko <mhocko@kernel.org> - 2016-06-21 10:40 +0200
    Re: mm, oom_reaper: How to handle race with oom_killer_disable() ? Michal Hocko <mhocko@kernel.org> - 2016-06-21 13:50 +0200
      Re: mm, oom_reaper: How to handle race with oom_killer_disable() ? Michal Hocko <mhocko@kernel.org> - 2016-06-21 15:30 +0200
        Re: mm, oom_reaper: How to handle race with oom_killer_disable() ? Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2016-06-21 17:40 +0200
          Re: mm, oom_reaper: How to handle race with oom_killer_disable() ? Michal Hocko <mhocko@kernel.org> - 2016-06-21 20:00 +0200
            Re: mm, oom_reaper: How to handle race with oom_killer_disable() ? Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2016-06-21 23:50 +0200
              Re: mm, oom_reaper: How to handle race with oom_killer_disable() ? Michal Hocko <mhocko@kernel.org> - 2016-06-22 08:50 +0200
                Re: mm, oom_reaper: How to handle race with oom_killer_disable() ? Michal Hocko <mhocko@kernel.org> - 2016-06-22 09:00 +0200
                Re: mm, oom_reaper: How to handle race with oom_killer_disable() ? Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2016-06-22 13:00 +0200
                Re: mm, oom_reaper: How to handle race with oom_killer_disable() ? Michal Hocko <mhocko@kernel.org> - 2016-06-22 14:10 +0200
                Re: mm, oom_reaper: How to handle race with oom_killer_disable() ? Michal Hocko <mhocko@kernel.org> - 2016-06-22 14:20 +0200
    Re: mm, oom_reaper: How to handle race with oom_killer_disable() ? Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2016-06-21 14:00 +0200

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