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Date:   Thu, 25 Jan 2018 16:00:16 -0800
From:   Andrew Morton <akpm@linux-foundation.org>
To:     David Rientjes <rientjes@google.com>
Cc:     Roman Gushchin <guro@fb.com>, Michal Hocko <mhocko@kernel.org>,
        Vladimir Davydov <vdavydov.dev@gmail.com>,
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        Tejun Heo <tj@kernel.org>, kernel-team@fb.com,
        cgroups@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [patch -mm v2 2/3] mm, memcg: replace cgroup aware oom killer
 mount option with tunable
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On Thu, 25 Jan 2018 15:53:48 -0800 (PST) David Rientjes <rientjes@google.com> wrote:

> Now that each mem cgroup on the system has a memory.oom_policy tunable to
> specify oom kill selection behavior, remove the needless "groupoom" mount
> option that requires (1) the entire system to be forced, perhaps
> unnecessarily, perhaps unexpectedly, into a single oom policy that
> differs from the traditional per process selection, and (2) a remount to
> change.
> 
> Instead of enabling the cgroup aware oom killer with the "groupoom" mount
> option, set the mem cgroup subtree's memory.oom_policy to "cgroup".

Can we retain the groupoom mount option and use its setting to set the
initial value of every memory.oom_policy?  That way the mount option
remains somewhat useful and we're back-compatible?