linux-kernel - Re: [patch] mm, oom: prevent soft lockup on memcg oom for UP systems

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Message-ID: <8395df04-9b7a-0084-4bb5-e430efe18b97@i-love.sakura.ne.jp>
Date:   Sat, 14 Mar 2020 08:32:54 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
To:     David Rientjes <rientjes@...gle.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Michal Hocko <mhocko@...nel.org>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [patch] mm, oom: prevent soft lockup on memcg oom for UP systems

On 2020/03/14 8:15, Tetsuo Handa wrote:
> If current thread is
> an OOM victim, schedule_timeout_killable(1) will give other threads (including
> the OOM reaper kernel thread) CPU time to run.

If current thread is an OOM victim, schedule_timeout_killable(1) will give other
threads (including the OOM reaper kernel thread) CPU time to run, by leaving
try_charge() path due to should_force_charge() == true and reaching do_exit() path
instead of returning to userspace code doing "for (;;);".

Unless the problem is that current thread cannot reach should_force_charge() check,
schedule_timeout_killable(1) should work.