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Date: Tue, 27 Jun 2017 14:03:17 +0200
From: Michal Hocko <mhocko@kernel.org>
Subject: Re: [RFC PATCH] mm, oom: allow oom reaper to race with exit_mmap
Message-ID: <20170627120317.GL28072@dhcp22.suse.cz>
References: <20170626130346.26314-1-mhocko@kernel.org>
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To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: linux-mm@kvack.org, rientjes@google.com, oleg@redhat.com, andrea@kernel.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org

On Tue 27-06-17 20:39:28, Tetsuo Handa wrote:
> 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?

In most cases yes. To be put it in other words. By the time exit_mmap
takes down_write there is nothing more oom reaper could reclaim.

-- 
Michal Hocko
SUSE Labs

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