linux-kernel - Re: [RFC PATCH] mm, oom: allow oom reaper to race with exit

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Message-Id: <201706272039.HGG51520.QOMHFVOFtOSJFL@I-love.SAKURA.ne.jp>
Date:   Tue, 27 Jun 2017 20:39:28 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:     mhocko@...nel.org
Cc:     linux-mm@...ck.org, rientjes@...gle.com, oleg@...hat.com,
        andrea@...nel.org, akpm@...ux-foundation.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] mm, oom: allow oom reaper to race with exit_mmap

Michal Hocko wrote:
> > I wonder why you prefer timeout based approach. Your patch will after all
> > set MMF_OOM_SKIP if operations between down_write() and up_write() took
> > more than one second.
> 
> if we reach down_write then we have unmapped the address space in
> exit_mmap and oom reaper cannot do much more.

So, by the time down_write() is called, majority of memory is already released, isn't it?