From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: tj@kernel.org
Cc: jiangshanlai@gmail.com, jstancek@redhat.com, linux-mm@kvack.org,
ltp@lists.linux.it
Subject: Re: [BUG] oom hangs the system, NMI backtrace shows most CPUs in shrink_slab
Date: Thu, 21 Jan 2016 00:54:56 +0900 [thread overview]
Message-ID: <201601210054.CEG04187.VFMQOFHOOLJFtS@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <20160120151044.GA5157@mtj.duckdns.org>
Tejun Heo wrote:
> On Wed, Jan 20, 2016 at 10:17:23PM +0900, Tetsuo Handa wrote:
> > What happens if memory allocation requests from items using this workqueue
> > got stuck due to OOM livelock? Are pending items in this workqueue cannot
> > be processed because this workqueue was created without WQ_MEM_RECLAIM?
>
> If something gets stuck due to OOM livelock, anything which tries to
> allocate memory can hang. That's why it's called a livelock.
> WQ_MEM_RECLAIM or not wouldn't make any difference.
>
> > I don't know whether accessing swap memory depends on this workqueue.
> > But if disk driver depends on this workqueue for accessing swap partition
> > on the disk, some event is looping inside memory allocator will result in
> > unable to process disk I/O request for accessing swap partition on the disk?
>
> What you're saying is too vauge for me to decipher exactly what you
> have on mind. Can you please elaborate?
>
In this thread ( http://lkml.kernel.org/r/569D06F8.4040209@redhat.com )
Jan hit an OOM stall where free memory does not increase even after OOM
victim and dying tasks terminated. I'm wondering why such thing can happen.
Since "Swap cache stats:" stopped increasing immediately after the OOM
stall began, I'm suspecting possibility that disk I/O event which is
needed for accessing swap memory is deferred due to cdrom I/O event
stalling at memory allocation when that disk I/O event is needed for
increasing free memory.
[ 6915.253288] MemAlloc: kworker/1:1(20708) seq=48 gfp=0x2400000 order=0 delay=20248
[ 6915.301353] MemAlloc: oom01(22011) seq=5135 gfp=0x24280ca order=0 delay=20641
[ 6915.317280] MemAlloc: oom01(22013) seq=5101 gfp=0x24280ca order=0 delay=20641
Maybe retesting with show_workqueue_state() added answers my question.
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next prev parent reply other threads:[~2016-01-20 15:55 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-18 15:38 Jan Stancek
2016-01-19 10:29 ` Tetsuo Handa
2016-01-19 15:13 ` Jan Stancek
2016-01-20 10:23 ` [BUG] oom hangs the system, NMI backtrace shows most CPUs inshrink_slab Tetsuo Handa
2016-01-20 13:17 ` [BUG] oom hangs the system, NMI backtrace shows most CPUs in shrink_slab Tetsuo Handa
2016-01-20 15:10 ` Tejun Heo
2016-01-20 15:54 ` Tetsuo Handa [this message]
2016-01-22 15:14 ` Jan Stancek
2016-01-23 6:30 ` Tetsuo Handa
2016-01-26 7:48 ` [LTP] " Jan Stancek
2016-01-26 14:46 ` Tetsuo Handa
2016-01-27 11:02 ` Tetsuo Handa
2016-01-28 15:48 ` Tetsuo Handa
2016-01-29 7:32 ` Jan Stancek
2016-01-29 12:35 ` Tetsuo Handa
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