From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: Michal Hocko <mhocko@kernel.org>
Cc: "Arkadiusz Miśkiewicz" <a.miskiewicz@gmail.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"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 v2] oom, oom_reaper: do not enqueue same task twice
Date: Sun, 27 Jan 2019 19:56:06 +0900 [thread overview]
Message-ID: <ec0d0580-a2dd-f329-9707-0cb91205a216@i-love.sakura.ne.jp> (raw)
In-Reply-To: <20190127083724.GA18811@dhcp22.suse.cz>
On 2019/01/27 17:37, Michal Hocko wrote:
> Thanks for the analysis and the patch. This should work, I believe but
> I am not really thrilled to overload the meaning of the MMF_UNSTABLE.
> The flag is meant to signal accessing address space is not stable and it
> is not aimed to synchronize oom reaper with the oom path.
>
> Can we make use mark_oom_victim directly? I didn't get to think that
> through right now so I might be missing something but this should
> prevent repeating queueing as well.
Yes, TIF_MEMDIE would work. But you are planning to remove TIF_MEMDIE. Also,
TIF_MEMDIE can't avoid enqueuing many threads sharing mm_struct to the OOM
reaper. There is no need to enqueue many threads sharing mm_struct because
the OOM reaper acts on mm_struct rather than task_struct. Thus, enqueuing
based on per mm_struct flag sounds better, but MMF_OOM_VICTIM cannot be
set from wake_oom_reaper(victim) because victim's mm might be already inside
exit_mmap() when wake_oom_reaper(victim) is called after task_unlock(victim).
We could reintroduce MMF_OOM_KILLED in commit 855b018325737f76
("oom, oom_reaper: disable oom_reaper for oom_kill_allocating_task")
if you don't like overloading the meaning of the MMF_UNSTABLE. But since
MMF_UNSTABLE is available in Linux 4.9+ kernels (which covers all LTS stable
versions with the OOM reaper support), we can temporarily use MMF_UNSTABLE
for ease of backporting.
next prev parent reply other threads:[~2019-01-27 10:56 UTC|newest]
Thread overview: 22+ 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>
2019-01-25 7:52 ` pids.current with invalid value for hours [5.0.0 rc3 git] Arkadiusz Miśkiewicz
2019-01-25 16:37 ` Tejun Heo
2019-01-25 19:47 ` Arkadiusz Miśkiewicz
2019-01-26 1:27 ` Tetsuo Handa
2019-01-26 2:41 ` Arkadiusz Miśkiewicz
2019-01-26 6:10 ` Tetsuo Handa
2019-01-26 7:55 ` Tetsuo Handa
2019-01-26 11:09 ` Tetsuo Handa
2019-01-26 11:29 ` Arkadiusz Miśkiewicz
2019-01-26 13:10 ` [PATCH v2] oom, oom_reaper: do not enqueue same task twice Tetsuo Handa
2019-01-27 8:37 ` Michal Hocko
2019-01-27 10:56 ` Tetsuo Handa [this message]
2019-01-27 11:40 ` Michal Hocko
2019-01-27 14:57 ` [PATCH v3] " Tetsuo Handa
2019-01-27 16:58 ` Michal Hocko
2019-01-27 23:00 ` Roman Gushchin
2019-01-28 18:15 ` Andrew Morton
2019-01-28 18:42 ` Michal Hocko
2019-01-28 21:53 ` Johannes Weiner
2019-01-29 10:34 ` Tetsuo Handa
2019-01-26 1:41 ` pids.current with invalid value for hours [5.0.0 rc3 git] Roman Gushchin
2019-01-26 2:28 ` Arkadiusz Miśkiewicz
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