linux-kernel - Re: [PATCH v3 2/3] mm, oom: remove redundant task_in_mem

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Date:   Thu, 27 Jun 2019 19:12:48 -0700
From:   Shakeel Butt <shakeelb@...gle.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Johannes Weiner <hannes@...xchg.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Roman Gushchin <guro@...com>,
        David Rientjes <rientjes@...gle.com>,
        KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Paul Jackson <pj@....com>, Linux MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 2/3] mm, oom: remove redundant task_in_mem_cgroup() check

On Tue, Jun 25, 2019 at 11:38 PM Michal Hocko <mhocko@...nel.org> wrote:
>
> On Mon 24-06-19 14:26:30, Shakeel Butt wrote:
> > oom_unkillable_task() can be called from three different contexts i.e.
> > global OOM, memcg OOM and oom_score procfs interface. At the moment
> > oom_unkillable_task() does a task_in_mem_cgroup() check on the given
> > process. Since there is no reason to perform task_in_mem_cgroup()
> > check for global OOM and oom_score procfs interface, those contexts
> > provide NULL memcg and skips the task_in_mem_cgroup() check. However for
> > memcg OOM context, the oom_unkillable_task() is always called from
> > mem_cgroup_scan_tasks() and thus task_in_mem_cgroup() check becomes
> > redundant. So, just remove the task_in_mem_cgroup() check altogether.
>
> Just a nit. Not only it is redundant but it is effectively a dead code
> after your previous patch.
>

I will update the commit message.

> > Signed-off-by: Shakeel Butt <shakeelb@...gle.com>
> > Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
>
> Acked-by: Michal Hocko <mhocko@...e.com>

Thanks