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From: Andrew Morton <akpm@linux-foundation.org>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: "Michal Hocko" <mhocko@kernel.org>,
	"Arkadiusz Miśkiewicz" <a.miskiewicz@gmail.com>,
	"Tejun Heo" <tj@kernel.org>,
	cgroups@vger.kernel.org, "Aleksa Sarai" <asarai@suse.de>,
	"Jay Kamat" <jgkamat@fb.com>, "Roman Gushchin" <guro@fb.com>,
	"Johannes Weiner" <hannes@cmpxchg.org>,
	linux-kernel@vger.kernel.org,
	"Linus Torvalds" <torvalds@linux-foundation.org>,
	linux-mm <linux-mm@kvack.org>
Subject: Re: [PATCH v3] oom, oom_reaper: do not enqueue same task twice
Date: Mon, 28 Jan 2019 10:15:13 -0800
Message-ID: <20190128101513.f35752d6210f0781d0de8d17@linux-foundation.org> (raw)
In-Reply-To: <e865a044-2c10-9858-f4ef-254bc71d6cc2@i-love.sakura.ne.jp>

On Sun, 27 Jan 2019 23:57:38 +0900 Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> wrote:

> Arkadiusz reported that enabling memcg's group oom killing causes
> strange memcg statistics where there is no task in a memcg despite
> the number of tasks in that memcg is not 0. It turned out that there
> is a bug in wake_oom_reaper() which allows enqueuing same task twice
> which makes impossible to decrease the number of tasks in that memcg
> due to a refcount leak.
> 
> This bug existed since the OOM reaper became invokable from
> task_will_free_mem(current) path in out_of_memory() in Linux 4.7,
> but memcg's group oom killing made it easier to trigger this bug by
> calling wake_oom_reaper() on the same task from one out_of_memory()
> request.
> 
> Fix this bug using an approach used by commit 855b018325737f76
> ("oom, oom_reaper: disable oom_reaper for oom_kill_allocating_task").
> As a side effect of this patch, this patch also avoids enqueuing
> multiple threads sharing memory via task_will_free_mem(current) path.
> 

Do we think this is serious enough to warrant a -stable backport?


  parent reply index

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <df806a77-3327-9db5-8be2-976fde1c84e5@gmail.com>
     [not found] ` <20190117122535.njcbqhlmzozdkncw@mikami>
     [not found]   ` <1d36b181-cbaf-6694-1a31-2f7f55d15675@gmail.com>
     [not found]     ` <96ef6615-a5df-30af-b4dc-417a18ca63f1@gmail.com>
     [not found]       ` <1cdbef13-564d-61a6-95f4-579d2cad243d@gmail.com>
     [not found]         ` <20190125163731.GJ50184@devbig004.ftw2.facebook.com>
     [not found]           ` <a95d004a-4358-7efc-6d21-12aac4411b32@gmail.com>
     [not found]             ` <480296c4-ed7a-3265-e84a-298e42a0f1d5@I-love.SAKURA.ne.jp>
     [not found]               ` <6da6ca69-5a6e-a9f6-d091-f89a8488982a@gmail.com>
     [not found]                 ` <72aa8863-a534-b8df-6b9e-f69cf4dd5c4d@i-love.sakura.ne.jp>
     [not found]                   ` <33a07810-6dbc-36be-5bb6-a279773ccf69@i-love.sakura.ne.jp>
     [not found]                     ` <34e97b46-0792-cc66-e0f2-d72576cdec59@i-love.sakura.ne.jp>
     [not found]                       ` <2b0c7d6c-c58a-da7d-6f0a-4900694ec2d3@gmail.com>
2019-01-26 13:10                         ` [PATCH v2] " Tetsuo Handa
2019-01-26 13:10                           ` Tetsuo Handa
2019-01-27  8:37                           ` Michal Hocko
2019-01-27 10:56                             ` Tetsuo Handa
2019-01-27 11:40                               ` Michal Hocko
2019-01-27 14:57                                 ` [PATCH v3] " Tetsuo Handa
2019-01-27 14:57                                   ` Tetsuo Handa
2019-01-27 16:58                                   ` Michal Hocko
2019-01-27 23:00                                   ` Roman Gushchin
2019-01-28 18:15                                   ` Andrew Morton [this message]
2019-01-28 18:42                                     ` Michal Hocko
2019-01-28 21:53                                   ` Johannes Weiner
2019-01-29 10:34                                     ` Tetsuo Handa

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