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From: peter enderborg <peter.enderborg@sony.com>
To: Michal Hocko <mhocko@kernel.org>,
	Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: linux-mm@kvack.org, rientjes@google.com,
	akpm@linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm,oom: Bring OOM notifier callbacks to outside of OOM killer.
Date: Mon, 25 Jun 2018 15:03:40 +0200	[thread overview]
Message-ID: <3d27f26e-68ba-d3c0-9518-cebeb2689aec@sony.com> (raw)
In-Reply-To: <20180620115531.GL13685@dhcp22.suse.cz>

On 06/20/2018 01:55 PM, Michal Hocko wrote:
> On Wed 20-06-18 20:20:38, Tetsuo Handa wrote:
>> Sleeping with oom_lock held can cause AB-BA lockup bug because
>> __alloc_pages_may_oom() does not wait for oom_lock. Since
>> blocking_notifier_call_chain() in out_of_memory() might sleep, sleeping
>> with oom_lock held is currently an unavoidable problem.
> Could you be more specific about the potential deadlock? Sleeping while
> holding oom lock is certainly not nice but I do not see how that would
> result in a deadlock assuming that the sleeping context doesn't sleep on
> the memory allocation obviously.

It is a mutex you are supposed to be able to sleep.  It's even exported.

>> As a preparation for not to sleep with oom_lock held, this patch brings
>> OOM notifier callbacks to outside of OOM killer, with two small behavior
>> changes explained below.
> Can we just eliminate this ugliness and remove it altogether? We do not
> have that many notifiers. Is there anything fundamental that would
> prevent us from moving them to shrinkers instead?


@Hocko Do you remember the lowmemorykiller from android? Some things might not be the right thing for shrinkers.

  parent reply	other threads:[~2018-06-25 13:03 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-20 11:20 [PATCH] mm,oom: Bring OOM notifier callbacks to outside of OOM killer Tetsuo Handa
2018-06-20 11:55 ` Michal Hocko
2018-06-20 12:21   ` Tetsuo Handa
2018-06-20 13:07     ` Michal Hocko
2018-06-25 13:03   ` peter enderborg [this message]
2018-06-25 13:07     ` Michal Hocko
2018-06-25 14:02       ` peter enderborg
2018-06-25 14:04       ` peter enderborg
2018-06-25 14:12         ` Michal Hocko
2018-06-20 22:36 ` David Rientjes
2018-06-21  7:31   ` Michal Hocko
2018-06-21 11:27     ` Tetsuo Handa
2018-06-21 12:05       ` Michal Hocko
2018-06-26 17:03       ` Paul E. McKenney
2018-06-26 20:10         ` Tetsuo Handa
2018-06-26 23:50           ` Paul E. McKenney
2018-06-27 10:52             ` Tetsuo Handa
2018-06-27 14:28               ` Paul E. McKenney
2018-06-27  7:22         ` Michal Hocko
2018-06-27 14:31           ` Paul E. McKenney
2018-06-28 11:39             ` Michal Hocko
2018-06-28 21:31               ` Paul E. McKenney
2018-06-29  9:04                 ` Michal Hocko
2018-06-29 12:52                   ` Paul E. McKenney
2018-06-29 13:26                     ` Michal Hocko
2018-06-30 17:05                       ` Paul E. McKenney
2018-07-02 12:00                         ` Michal Hocko
2018-07-02 21:37                         ` Paul E. McKenney
2018-07-03  7:24                           ` Michal Hocko
2018-07-03 16:01                             ` Paul E. McKenney
2018-07-06  5:39                               ` Michal Hocko
2018-07-06 12:22                                 ` Paul E. McKenney
2018-06-29 14:35                     ` Tetsuo Handa
2018-06-30 17:19                       ` Paul E. McKenney

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