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From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: mst@redhat.com
Cc: mhocko@kernel.org, linux-mm@kvack.org
Subject: Re: [RFC] [PATCH] mm,oom: Offload OOM notify callback to a kernel thread.
Date: Mon, 2 Oct 2017 23:44:45 +0900	[thread overview]
Message-ID: <201710022344.JII17368.HQtLOMJOOSFFVF@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <20171002171641-mutt-send-email-mst@kernel.org>

Michael S. Tsirkin wrote:
> > Yes, conditional GFP_KERNEL allocation attempt from virtqueue_add() might
> > still cause this deadlock. But that depends on whether you can trigger this
> > deadlock. As far as I know, there is no report. Thus, I think that avoiding
> > theoretical deadlock using timeout will be sufficient.
> 
> 
> So first of all IMHO GFP_KERNEL allocations do not happen in
> virtqueue_add_outbuf at all. They only trigger through add_sgs.

I did not notice that total_sg == 1 is true for virtqueue_add_outbuf().

> 
> IMHO this is an API bug, we should just drop the gfp parameter
> from this API.

OK.

> 
> 
> so the issue is balloon_page_enqueue only.
> 

Since you explained that there is "the deflate on OOM flag", we don't
want to skip deflating upon lock contention.

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  reply	other threads:[~2017-10-02 14:44 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-11 10:27 mm, virtio: possible OOM lockup at virtballoon_oom_notify() Tetsuo Handa
2017-09-29  4:00 ` Michael S. Tsirkin
2017-09-29  4:44   ` Tetsuo Handa
2017-10-01  5:44     ` [RFC] [PATCH] mm, oom: Offload OOM notify callback to a kernel thread Tetsuo Handa
2017-10-02  3:59       ` [RFC] [PATCH] mm,oom: " Michael S. Tsirkin
2017-10-02  9:06         ` Michal Hocko
2017-10-02 11:33           ` [RFC] [PATCH] mm, oom: " Tetsuo Handa
2017-10-02 11:50             ` Michal Hocko
2017-10-02 13:05               ` [RFC] [PATCH] mm,oom: " Tetsuo Handa
2017-10-02 13:13                 ` Michal Hocko
2017-10-02 13:52                   ` Tetsuo Handa
2017-10-02 14:23                     ` Michael S. Tsirkin
2017-10-02 14:44                       ` Tetsuo Handa [this message]
2017-10-07 11:30                         ` Tetsuo Handa
2017-10-09  7:46                           ` Michal Hocko
2017-10-09  8:06                             ` Tetsuo Handa
2017-10-09 12:28                               ` Michal Hocko
2017-10-09 13:31                                 ` Tetsuo Handa
2017-10-09 13:37                                   ` Michal Hocko
2017-10-09 14:24                                     ` Michael S. Tsirkin
2017-10-02 14:15                   ` Michael S. Tsirkin
2017-10-02 14:11               ` Michael S. Tsirkin
2017-10-02 14:19                 ` Michal Hocko
2017-10-02 14:29                   ` Michael S. Tsirkin
2017-10-02 14:31                     ` Michal Hocko

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