From mboxrd@z Thu Jan  1 00:00:00 1970
From: Roman Gushchin <guro@fb.com>
Subject: Re: [v9 3/5] mm, oom: cgroup-aware OOM killer
Date: Wed, 4 Oct 2017 16:04:52 +0100
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To: Michal Hocko <mhocko@kernel.org>
Cc: linux-mm@kvack.org, Vladimir Davydov <vdavydov.dev@gmail.com>, Johannes Weiner <hannes@cmpxchg.org>, Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>, David Rientjes <rientjes@google.com>, Andrew Morton <akpm@linux-foundation.org>, Tejun Heo <tj@kernel.org>, kernel-team@fb.com, cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org

On Tue, Oct 03, 2017 at 04:22:46PM +0200, Michal Hocko wrote:
> On Tue 03-10-17 15:08:41, Roman Gushchin wrote:
> > On Tue, Oct 03, 2017 at 03:36:23PM +0200, Michal Hocko wrote:
> [...]
> > > I guess we want to inherit the value on the memcg creation but I agree
> > > that enforcing parent setting is weird. I will think about it some more
> > > but I agree that it is saner to only enforce per memcg value.
> > 
> > I'm not against, but we should come up with a good explanation, why we're
> > inheriting it; or not inherit.
> 
> Inheriting sounds like a less surprising behavior. Once you opt in for
> oom_group you can expect that descendants are going to assume the same
> unless they explicitly state otherwise.

Not sure I understand why. Setting memory.oom_group on a child memcg
has absolutely no meaning until memory.max is also set. In case of OOM
scoped to the parent memcg or above, parent's value defines the behavior.

If a user decides to create a separate OOM domain (be setting the hard
memory limit), he/she can also make a decision on how OOM event should
be handled.

Thanks!