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From: Michal Hocko <mhocko@suse.cz>
To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: linux-mm@kvack.org, akpm@linux-foundation.org, oleg@redhat.com,
	rientjes@google.com, vdavydov@parallels.com, mst@redhat.com
Subject: Re: [PATCH 6/8] mm,oom_reaper: Stop clearing TIF_MEMDIE on remote thread.
Date: Thu, 7 Jul 2016 18:54:21 +0200	[thread overview]
Message-ID: <20160707165421.GP5379@dhcp22.suse.cz> (raw)
In-Reply-To: <201607080110.FHF78128.VOOLFOQFJFSHtM@I-love.SAKURA.ne.jp>

On Fri 08-07-16 01:10:02, Tetsuo Handa wrote:
> Michal Hocko wrote:
> > On Sun 03-07-16 11:40:41, Tetsuo Handa wrote:
> > > >From 00b7a14653c9700429f89e4512f6000a39cce59d Mon Sep 17 00:00:00 2001
> > > From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> > > Date: Sat, 2 Jul 2016 23:03:03 +0900
> > > Subject: [PATCH 6/8] mm,oom_reaper: Stop clearing TIF_MEMDIE on remote thread.
> > > 
> > > Since oom_has_pending_mm() controls whether to select next OOM victim,
> > > we no longer need to clear TIF_MEMDIE on remote thread. Therefore,
> > > revert related changes in commit 36324a990cf578b5 ("oom: clear TIF_MEMDIE
> > > after oom_reaper managed to unmap the address space") and
> > > commit e26796066fdf929c ("oom: make oom_reaper freezable") and
> > > commit 74070542099c66d8 ("oom, suspend: fix oom_reaper vs.
> > > oom_killer_disable race").
> > 
> > The last revert is not safe. See
> > http://lkml.kernel.org/r/1467365190-24640-3-git-send-email-mhocko@kernel.org
> 
> Why?

Because there is no guarantee of calling exit_oom_victim and thus
oom_disable making a forward progress. The changelog referenced above
tries to explain that.

-- 
Michal Hocko
SUSE Labs

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  reply	other threads:[~2016-07-07 16:54 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-03  2:35 [PATCH 0/8] Change OOM killer to use list of mm_struct Tetsuo Handa
2016-07-03  2:36 ` [PATCH 1/8] mm,oom_reaper: Remove pointless kthread_run() failure check Tetsuo Handa
2016-07-03 12:42   ` Oleg Nesterov
2016-07-03 16:03     ` Tetsuo Handa
2016-07-03 17:10       ` Oleg Nesterov
2016-07-03 21:53         ` Tetsuo Handa
2016-07-04 11:13           ` Oleg Nesterov
2016-07-07 11:14           ` Michal Hocko
2016-07-03  2:37 ` [PATCH 2/8] mm,oom_reaper: Reduce find_lock_task_mm() usage Tetsuo Handa
2016-07-07 11:19   ` Michal Hocko
2016-07-03  2:38 ` [PATCH 3/8] mm,oom: Use list of mm_struct used by OOM victims Tetsuo Handa
2016-07-04 10:39   ` Oleg Nesterov
2016-07-04 12:50     ` Tetsuo Handa
2016-07-04 18:25       ` Oleg Nesterov
2016-07-05 10:43         ` Tetsuo Handa
2016-07-05 20:52           ` Oleg Nesterov
2016-07-06  8:53             ` Oleg Nesterov
2016-07-06 11:43               ` Tetsuo Handa
2016-07-07 11:31   ` Michal Hocko
2016-07-03  2:39 ` [PATCH 4/8] mm,oom: Remove OOM_SCAN_ABORT case Tetsuo Handa
2016-07-03  2:40 ` [PATCH 5/8] mm,oom: Remove unused signal_struct->oom_victims Tetsuo Handa
2016-07-07 14:03   ` Michal Hocko
2016-07-03  2:40 ` [PATCH 6/8] mm,oom_reaper: Stop clearing TIF_MEMDIE on remote thread Tetsuo Handa
2016-07-07 14:06   ` Michal Hocko
2016-07-07 16:10     ` Tetsuo Handa
2016-07-07 16:54       ` Michal Hocko [this message]
2016-07-03  2:41 ` [PATCH 7/8] mm,oom_reaper: Pass OOM victim's comm and pid values via mm_struct Tetsuo Handa
2016-07-03  2:41 ` [PATCH 8/8] mm,oom_reaper: Make OOM reaper use list of mm_struct Tetsuo Handa
2016-07-04 10:40   ` Oleg Nesterov
2016-07-07 14:15   ` Michal Hocko
2016-07-07 11:04 ` [PATCH 0/8] Change OOM killer to " Michal Hocko

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