linux-kernel - Re: [PATCH] memcg: oom: ignore oom warnings from memory.max

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Message-ID: <20200430192907.GA2436@cmpxchg.org>
Date:   Thu, 30 Apr 2020 15:29:07 -0400
From:   Johannes Weiner <hannes@...xchg.org>
To:     Shakeel Butt <shakeelb@...gle.com>
Cc:     Roman Gushchin <guro@...com>, Michal Hocko <mhocko@...nel.org>,
        Greg Thelen <gthelen@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        cgroups@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] memcg: oom: ignore oom warnings from memory.max

On Thu, Apr 30, 2020 at 11:27:12AM -0700, Shakeel Butt wrote:
> Lowering memory.max can trigger an oom-kill if the reclaim does not
> succeed. However if oom-killer does not find a process for killing, it
> dumps a lot of warnings.
> 
> Deleting a memcg does not reclaim memory from it and the memory can
> linger till there is a memory pressure. One normal way to proactively
> reclaim such memory is to set memory.max to 0 just before deleting the
> memcg. However if some of the memcg's memory is pinned by others, this
> operation can trigger an oom-kill without any process and thus can log a
> lot un-needed warnings. So, ignore all such warnings from memory.max.

Can't you set memory.high=0 instead? It does the reclaim portion of
memory.max, without the actual OOM killing that causes you problems.