From: Michal Hocko <mhocko@kernel.org>
To: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
David Rientjes <rientjes@google.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] exit: clear TIF_MEMDIE after exit_task_work
Date: Mon, 29 Feb 2016 19:44:44 +0100 [thread overview]
Message-ID: <20160229184444.GT16930@dhcp22.suse.cz> (raw)
In-Reply-To: <20160229182131.GP16930@dhcp22.suse.cz>
On Mon 29-02-16 19:21:31, Michal Hocko wrote:
> On Mon 29-02-16 20:02:09, Vladimir Davydov wrote:
> > An mm_struct may be pinned by a file. An example is vhost-net device
> > created by a qemu/kvm (see vhost_net_ioctl -> vhost_net_set_owner ->
> > vhost_dev_set_owner). If such process gets OOM-killed, the reference to
> > its mm_struct will only be released from exit_task_work -> ____fput ->
> > __fput -> vhost_net_release -> vhost_dev_cleanup, which is called after
> > exit_mmap, where TIF_MEMDIE is cleared. As a result, we can start
> > selecting the next victim before giving the last one a chance to free
> > its memory. In practice, this leads to killing several VMs along with
> > the fattest one.
>
> I am wondering why our PF_EXITING protection hasn't fired up.
OK, I guess I can see it. exit_mm has done tsk->mm = NULL and so we are
skipping over that task because oom_scan_process_thread hasn't checked
PF_EXITING. I will try to think about this some more tomorrow with a
fresh brain.
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2016-02-29 18:44 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-29 17:02 [PATCH] exit: clear TIF_MEMDIE after exit_task_work Vladimir Davydov
2016-02-29 18:21 ` Michal Hocko
2016-02-29 18:44 ` Michal Hocko [this message]
2016-03-01 15:52 ` Michal Hocko
2016-03-01 15:57 ` Michael S. Tsirkin
2016-03-01 16:08 ` Michal Hocko
2016-03-01 16:14 ` Michael S. Tsirkin
2016-03-01 16:22 ` Michael S. Tsirkin
2016-03-01 16:35 ` Michal Hocko
2016-03-01 16:46 ` Michael S. Tsirkin
2016-03-01 17:17 ` Michal Hocko
2016-03-01 17:20 ` Michael S. Tsirkin
2016-03-14 16:39 ` Michal Hocko
2016-06-07 12:50 ` Michal Hocko
2016-06-13 11:50 ` Michal Hocko
2016-06-13 13:52 ` Tetsuo Handa
2016-06-13 14:00 ` Michal Hocko
2016-06-13 18:11 ` Michael S. Tsirkin
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