Re: [PATCH v2] mm,oom: exclude oom_task_origin processes if they are OOM-unkillable.

From	Michal Hocko <mhocko@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2] mm,oom: exclude oom_task_origin processes if they are OOM-unkillable.
Date	2016-02-18 13:10 +0100
Message-ID	<r3vzd-5gf-47@gated-at.bofh.it> (permalink)
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On Thu 18-02-16 19:30:12, Tetsuo Handa wrote:
[...]
> Commit 9cbb78bb314360a8 changed oom_scan_process_thread() to
> always pass memcg == NULL by removing memcg argument from
> oom_scan_process_thread(). As a result, after that commit,
> we are doing test_tsk_thread_flag(p, TIF_MEMDIE) check and
> oom_task_origin(p) check between two oom_unkillable_task()
> calls of memcg OOM case. Why don't we skip these checks by
> passing memcg != NULL to first oom_unkillable_task() call?
> Was this change by error?

I am not really sure I understand your question.  The point is
that mem_cgroup_out_of_memory does for_each_mem_cgroup_tree which
means that only tasks from the given memcg hierarchy is checked and
oom_unkillable_task cares about memcg only for

        /* When mem_cgroup_out_of_memory() and p is not member of the group */
        if (memcg && !task_in_mem_cgroup(p, memcg))
                return true;

which is never true by definition. I guess we can safely remove the memcg
argument from oom_badness and oom_unkillable_task. At least from a quick
glance...
-- 
Michal Hocko
SUSE Labs

Thread

[PATCH v2] mm,oom: exclude oom_task_origin processes if they are OOM-unkillable. Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2016-02-17 15:40 +0100
  Re: [PATCH v2] mm,oom: exclude oom_task_origin processes if they are  OOM-unkillable. Michal Hocko <mhocko@kernel.org> - 2016-02-17 15:50 +0100
  Re: [PATCH v2] mm,oom: exclude oom_task_origin processes if they  are OOM-unkillable. David Rientjes <rientjes@google.com> - 2016-02-17 23:40 +0100
    Re: [PATCH v2] mm,oom: exclude oom_task_origin processes if they are  OOM-unkillable. Michal Hocko <mhocko@kernel.org> - 2016-02-18 09:10 +0100
      Re: [PATCH v2] mm,oom: exclude oom_task_origin processes if they are OOM-unkillable. Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2016-02-18 11:40 +0100
        Re: [PATCH v2] mm,oom: exclude oom_task_origin processes if they are  OOM-unkillable. Michal Hocko <mhocko@kernel.org> - 2016-02-18 13:10 +0100
          Re: [PATCH v2] mm,oom: exclude oom_task_origin processes if they are  OOM-unkillable. Michal Hocko <mhocko@kernel.org> - 2016-02-18 13:20 +0100
            Re: [PATCH v2] mm,oom: exclude oom_task_origin processes if they are OOM-unkillable. Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2016-02-19 16:10 +0100
              Re: [PATCH v2] mm,oom: exclude oom_task_origin processes if they are  OOM-unkillable. Michal Hocko <mhocko@kernel.org> - 2016-02-19 16:20 +0100

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