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From: Michal Hocko <mhocko@kernel.org>
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
Subject: Re: [RFC PATCH] mm, oom: allow oom reaper to race with exit_mmap
Date: Tue, 27 Jun 2017 14:03:17 +0200	[thread overview]
Message-ID: <20170627120317.GL28072@dhcp22.suse.cz> (raw)
In-Reply-To: <201706272039.HGG51520.QOMHFVOFtOSJFL@I-love.SAKURA.ne.jp>

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

WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org>
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
Subject: Re: [RFC PATCH] mm, oom: allow oom reaper to race with exit_mmap
Date: Tue, 27 Jun 2017 14:03:17 +0200	[thread overview]
Message-ID: <20170627120317.GL28072@dhcp22.suse.cz> (raw)
In-Reply-To: <201706272039.HGG51520.QOMHFVOFtOSJFL@I-love.SAKURA.ne.jp>

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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  reply	other threads:[~2017-06-27 12:03 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-26 13:03 [RFC PATCH] mm, oom: allow oom reaper to race with exit_mmap Michal Hocko
2017-06-26 13:03 ` Michal Hocko
2017-06-27 10:52 ` Tetsuo Handa
2017-06-27 10:52   ` Tetsuo Handa
2017-06-27 11:26   ` Michal Hocko
2017-06-27 11:26     ` Michal Hocko
2017-06-27 11:39     ` Tetsuo Handa
2017-06-27 11:39       ` Tetsuo Handa
2017-06-27 12:03       ` Michal Hocko [this message]
2017-06-27 12:03         ` Michal Hocko
2017-06-27 13:31         ` Tetsuo Handa
2017-06-27 13:31           ` Tetsuo Handa
2017-06-27 13:55           ` Michal Hocko
2017-06-27 13:55             ` Michal Hocko
2017-06-27 14:26             ` Tetsuo Handa
2017-06-27 14:26               ` Tetsuo Handa
2017-06-27 14:41               ` Michal Hocko
2017-06-27 14:41                 ` Michal Hocko
2017-07-11  0:01   ` David Rientjes
2017-07-11  0:01     ` David Rientjes
2017-06-29  8:46 ` Michal Hocko
2017-06-29  8:46   ` Michal Hocko
2017-07-19  5:55   ` Michal Hocko
2017-07-19  5:55     ` Michal Hocko
2017-07-20  1:18     ` Hugh Dickins
2017-07-20  1:18       ` Hugh Dickins
2017-07-20 13:05       ` Michal Hocko
2017-07-20 13:05         ` Michal Hocko
2017-07-24  6:39         ` Hugh Dickins
2017-07-24  6:39           ` Hugh Dickins
2017-07-10 23:55 ` David Rientjes
2017-07-10 23:55   ` David Rientjes
2017-07-11  6:58   ` Michal Hocko
2017-07-11  6:58     ` Michal Hocko
2017-07-11 20:40     ` David Rientjes
2017-07-11 20:40       ` David Rientjes
2017-07-12  7:12       ` Michal Hocko
2017-07-12  7:12         ` Michal Hocko

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