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,
vdavydov@parallels.com, akpm@linux-foundation.org
Subject: Re: [PATCH 4/6] mm, oom: skip vforked tasks from being selected
Date: Thu, 2 Jun 2016 14:55:57 +0200 [thread overview]
Message-ID: <20160602125556.GO1995@dhcp22.suse.cz> (raw)
In-Reply-To: <201606022031.BIB56744.OFSFQOOtLJMFVH@I-love.SAKURA.ne.jp>
On Thu 02-06-16 20:31:57, Tetsuo Handa wrote:
> Michal Hocko wrote:
> > OK, but the memory is allocated on behalf of the parent already, right?
>
> What does "the memory is allocated on behalf of the parent already" mean?
It means that vforked task cannot allocate a new memory directly. Sure
it can get a copy of what parent already has allocated during execve but
that is under control of the parent. If the parent is OOM_SCORE_ADJ_MIN
then it should better be careful how it spawns new tasks.
> The memory used for argv[]/envp[] may not yet be visible from mm_struct when
> the OOM killer is invoked.
>
> > And the patch doesn't prevent parent from being selected and the vfroked
> > child being killed along the way as sharing the mm with it. So what
> > exactly this patch changes for this test case? What am I missing?
>
> If the parent is OOM_SCORE_ADJ_MIN and vfork()ed child doing execve()
> with large argv[]/envp[] is not OOM_SCORE_ADJ_MIN, we should not hesitate
> to OOM-kill vfork()ed child even if the parent is not OOM-killable.
>
> vfork()
> set_oom_adj()
> exec()
Well the whole point of this patch is to not select such a task because
it makes only very limitted sense. It cannot really free much memory -
well except when parent is doing something realy stupid which I am not
really sure we should care about.
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2016-06-02 12:56 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-30 13:05 [PATCH 0/6 -v2] Handle oom bypass more gracefully Michal Hocko
2016-05-30 13:05 ` [PATCH 1/6] proc, oom: drop bogus task_lock and mm check Michal Hocko
2016-05-30 13:49 ` Vladimir Davydov
2016-05-30 17:43 ` Oleg Nesterov
2016-05-31 7:32 ` Michal Hocko
2016-05-31 22:53 ` Oleg Nesterov
2016-06-01 6:53 ` Michal Hocko
2016-06-01 10:41 ` Tetsuo Handa
2016-06-01 10:48 ` Michal Hocko
2016-05-30 13:05 ` [PATCH 2/6] proc, oom_adj: extract oom_score_adj setting into a helper Michal Hocko
2016-05-30 13:05 ` [PATCH 3/6] mm, oom_adj: make sure processes sharing mm have same view of oom_score_adj Michal Hocko
2016-05-31 7:41 ` Michal Hocko
2016-05-30 13:05 ` [PATCH 4/6] mm, oom: skip vforked tasks from being selected Michal Hocko
2016-05-30 19:28 ` Oleg Nesterov
2016-05-31 7:42 ` Michal Hocko
2016-05-31 21:43 ` Oleg Nesterov
2016-06-01 7:09 ` Michal Hocko
2016-06-01 14:12 ` Tetsuo Handa
2016-06-01 14:25 ` Michal Hocko
2016-06-02 10:45 ` Tetsuo Handa
2016-06-02 11:20 ` Michal Hocko
2016-06-02 11:31 ` Tetsuo Handa
2016-06-02 12:55 ` Michal Hocko [this message]
2016-05-30 13:05 ` [PATCH 5/6] mm, oom: kill all tasks sharing the mm Michal Hocko
2016-05-30 18:18 ` Oleg Nesterov
2016-05-31 7:43 ` Michal Hocko
2016-05-31 21:48 ` Oleg Nesterov
2016-05-30 13:05 ` [PATCH 6/6] mm, oom: fortify task_will_free_mem Michal Hocko
2016-05-30 17:35 ` Oleg Nesterov
2016-05-31 7:46 ` Michal Hocko
2016-05-31 22:29 ` Oleg Nesterov
2016-06-01 7:03 ` Michal Hocko
2016-05-31 15:03 ` Tetsuo Handa
2016-05-31 15:10 ` Michal Hocko
2016-05-31 15:29 ` Tetsuo Handa
2016-06-01 7:25 ` Michal Hocko
2016-06-01 12:04 ` Tetsuo Handa
2016-06-01 12:43 ` Michal Hocko
2016-06-02 14:03 ` [PATCH 7/6] mm, oom: task_will_free_mem should skip oom_reaped tasks Michal Hocko
2016-06-02 15:24 ` Tetsuo Handa
2016-06-02 15:50 ` Michal Hocko
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