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From: Matthias Dahl <ml_linux-kernel@binary-island.eu>
To: Michal Hocko <mhocko@kernel.org>
Cc: linux-raid@vger.kernel.org, linux-mm@kvack.org,
	dm-devel@redhat.com, linux-kernel@vger.kernel.org
Subject: Re: Page Allocation Failures/OOM with dm-crypt on software RAID10 (Intel Rapid Storage)
Date: Tue, 12 Jul 2016 14:42:12 +0200	[thread overview]
Message-ID: <e6c2087730e530e77c2b12d50495bdc9@mail.ud19.udmedia.de> (raw)
In-Reply-To: <20160712114920.GF14586@dhcp22.suse.cz>

Hello Michal...

On 2016-07-12 13:49, Michal Hocko wrote:

> I am not a storage expert (not even mention dm-crypt). But what those
> counters say is that the IO completion doesn't trigger so the
> PageWriteback flag is still set. Such a page is not reclaimable
> obviously. So I would check the IO delivery path and focus on the
> potential dm-crypt involvement if you suspect this is a contributing
> factor.

Sounds reasonable... except that I have no clue how to trace that with
the limited means I have at my disposal right now and with the limited
knowledge I have of the kernel internals. ;-)

> Who is consuming those objects? Where is the rest 70% of memory hiding?

Is there any way to get a more detailed listing of where the memory is
spent while dd is running? Something I could pipe every 500ms or so for
later analysis or so?

> Writer will get throttled but the concurrent memory consumer will not
> normally. So you can end up in this situation.

Hm, okay. I am still confused though: If I, for example, let dd do the
exact same thing on a raw partition on the RAID10, nothing like that
happens. Wouldn't we have the same race and problem then too...? It is
only with dm-crypt in-between that all of this shows itself. But I do
somehow suspect the RAID10 Intel Rapid Storage to be the cause or at
least partially.

Like I said, if you have any pointers how I could further trace this
or figure out who is exactly consuming what memory, that would be very
helpful... Thanks.

So long,
Matthias

-- 
Dipl.-Inf. (FH) Matthias Dahl | Software Engineer | binary-island.eu
  services: custom software [desktop, mobile, web], server administration

  parent reply	other threads:[~2016-07-12 12:42 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-12  8:27 Page Allocation Failures/OOM with dm-crypt on software RAID10 (Intel Rapid Storage) Matthias Dahl
2016-07-12  9:50 ` Michal Hocko
2016-07-12 11:28   ` Matthias Dahl
2016-07-12 11:49     ` Michal Hocko
2016-07-12 11:59       ` Michal Hocko
2016-07-12 12:42       ` Matthias Dahl [this message]
2016-07-12 14:07         ` Michal Hocko
2016-07-12 14:56           ` Matthias Dahl
2016-07-13 11:21             ` Michal Hocko
2016-07-13 12:18               ` Michal Hocko
2016-07-13 13:18                 ` Matthias Dahl
2016-07-13 13:47                   ` Michal Hocko
2016-07-13 15:32                     ` Matthias Dahl
2016-07-13 16:24                       ` [dm-devel] " Ondrej Kozina
2016-07-13 18:24                         ` Matthias Dahl
2016-07-14 11:18                     ` Tetsuo Handa
2016-07-15  7:11                       ` Page Allocation Failures/OOM with dm-crypt on software RAID10 (Intel Rapid Storage) with check/repair/sync Matthias Dahl
2016-07-18  7:24                         ` Matthias Dahl

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