linux-kernel - Re: [RFC PATCH] mm/oom_kill: allow oom kill allocating task for non-global case

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Message-ID: <20210609143534.v65qknfihqimiivd@ava.usersys.com>
Date:   Wed, 9 Jun 2021 15:35:34 +0100
From:   Aaron Tomlin <atomlin@...hat.com>
To:     Michal Hocko <mhocko@...e.com>
Cc:     Waiman Long <llong@...hat.com>, Shakeel Butt <shakeelb@...gle.com>,
        Linux MM <linux-mm@...ck.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] mm/oom_kill: allow oom kill allocating task for
 non-global case

On Tue 2021-06-08 08:22 +0200, Michal Hocko wrote:
> Is it possible the only eligible task has been killed and oom reaped
> already?

Yes, I suspect so; and I had a look at the vmcore, the task in the OOM
report is no longer present. Therefore, I suspect the task namely "node"
(i.e. PID 1703345) was OOM killed i.e. a SIGKILL was sent and was granted
access to memory reserves and selected/or choosen by the OOM reaper for
termination; the victim then raised a page fault that triggered yet
another "charge" in the memcg that exceeded the memory limit set on the
container; and since no other task in the memcg had a suitable OOM score
and the allocating task/or victim was "unkillable" i.e. already selected
for termination by the OOM reaper, we got the message: "Out of memory and
no killable processes...".

-- 
Aaron Tomlin