linux-kernel - Re: [v6 3/4] mm, oom: introduce oom

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Date:   Mon, 28 Aug 2017 13:54:20 -0700 (PDT)
From:   David Rientjes <rientjes@...gle.com>
To:     Roman Gushchin <guro@...com>
cc:     Michal Hocko <mhocko@...nel.org>, linux-mm@...ck.org,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Tejun Heo <tj@...nel.org>, kernel-team@...com,
        cgroups@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [v6 3/4] mm, oom: introduce oom_priority for memory cgroups

On Thu, 24 Aug 2017, Roman Gushchin wrote:

> > > Do you have an example, which can't be effectively handled by an approach
> > > I'm suggesting?
> > 
> > No, I do not have any which would be _explicitly_ requested but I do
> > envision new requirements will emerge. The most probable one would be
> > kill the youngest container because that would imply the least amount of
> > work wasted.
> 
> I agree, this a nice feature. It can be implemented in userspace
> by setting oom_priority.
> 

Yes, the "kill the newest memory cgroup as a tiebreak" is not strictly 
required in the kernel and no cgroup should depend on this implementation 
detail to avoid being killed if it shares the same memory.oom_priority as 
another cgroup.  As you mention, it can be effectively implemented by 
userspace itself.