From: Michal Hocko <mhocko@kernel.org>
To: linux-mm@kvack.org
Cc: Mikulas Patocka <mpatocka@redhat.com>,
Ondrej Kozina <okozina@redhat.com>,
David Rientjes <rientjes@google.com>,
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
Mel Gorman <mgorman@suse.de>, Neil Brown <neilb@suse.de>,
Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
dm-devel@redhat.com
Subject: [RFC PATCH 0/2] mempool vs. page allocator interaction
Date: Mon, 18 Jul 2016 10:39:22 +0200 [thread overview]
Message-ID: <1468831164-26621-1-git-send-email-mhocko@kernel.org> (raw)
Hi,
there have been two issues identified when investigating dm-crypt
backed swap recently [1]. The first one looks like a regression from
f9054c70d28b ("mm, mempool: only set __GFP_NOMEMALLOC if there are free
elements") because swapout path can now deplete all the available memory
reserves. The first patch tries to address that issue by dropping
__GFP_NOMEMALLOC only to TIF_MEMDIE tasks.
The second issue is that dm writeout path which relies on mempool
allocator gets throttled by the direct reclaim in throttle_vm_writeout
which just makes the whole memory pressure problem even worse. The
patch2 just makes sure that we annotate mempool users to be throttled
less by PF_LESS_THROTTLE flag and prevent from throttle_vm_writeout for
that path. mempool users are usually the IO path and throttle them less
sounds like a reasonable way to go.
I do not have any more complicated dm setup available so I would
appreciate if dm people (CCed) could give these two a try.
Also it would be great to iron out concerns from David. He has posted a
deadlock stack trace [2] which has led to f9054c70d28b which is bio
allocation lockup because the TIF_MEMDIE process cannot make a forward
progress without access to memory reserve. This case should be fixed by
patch 1 AFAICS. There are other potential cases when the stuck mempool
is called from PF_MEMALLOC context and blocks the oom victim indirectly
(over a lock) but I believe those are much less likely and we have the
oom reaper to make a forward progress.
Sorry of pulling the discussion outside of the original email thread
but there were more lines of dicussion there and I felt discussing
particualr solution with its justification has a greater chance of
moving towards a solution. I am sending this as an RFC because this
needs a deep review as there might be other side effects I do not see
(especially about patch 2).
Any comments, suggestions are welcome.
---
[1] http://lkml.kernel.org/r/alpine.LRH.2.02.1607111027080.14327@file01.intranet.prod.int.rdu2.redhat.com
[2] http://lkml.kernel.org/r/alpine.DEB.2.10.1607131644590.92037@chino.kir.corp.google.com
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next reply other threads:[~2016-07-18 8:39 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-18 8:39 Michal Hocko [this message]
2016-07-18 8:41 ` [RFC PATCH 1/2] mempool: do not consume memory reserves from the reclaim path Michal Hocko
2016-07-18 8:41 ` [RFC PATCH 2/2] mm, mempool: do not throttle PF_LESS_THROTTLE tasks Michal Hocko
2016-07-19 21:50 ` Mikulas Patocka
2016-07-22 8:46 ` NeilBrown
2016-07-22 9:04 ` NeilBrown
2016-07-22 9:15 ` Michal Hocko
2016-07-23 0:12 ` NeilBrown
2016-07-25 8:32 ` Michal Hocko
2016-07-25 19:23 ` Michal Hocko
2016-07-26 7:07 ` Michal Hocko
2016-07-27 3:43 ` [dm-devel] " NeilBrown
2016-07-27 18:24 ` Michal Hocko
2016-07-27 21:33 ` NeilBrown
2016-07-28 7:17 ` Michal Hocko
2016-08-03 12:53 ` Mikulas Patocka
2016-08-03 14:34 ` Michal Hocko
2016-08-04 18:49 ` Mikulas Patocka
2016-08-12 12:32 ` Michal Hocko
2016-08-13 17:34 ` Mikulas Patocka
2016-08-14 10:34 ` Michal Hocko
2016-08-15 16:15 ` Mikulas Patocka
2016-11-23 21:11 ` Mikulas Patocka
2016-11-24 13:29 ` Michal Hocko
2016-11-24 17:10 ` Mikulas Patocka
2016-11-28 14:06 ` Michal Hocko
2016-07-25 21:52 ` Mikulas Patocka
2016-07-26 7:25 ` Michal Hocko
2016-07-27 4:02 ` [dm-devel] " NeilBrown
2016-07-27 14:28 ` Mikulas Patocka
2016-07-27 18:40 ` Michal Hocko
2016-08-03 13:59 ` Mikulas Patocka
2016-08-03 14:42 ` Michal Hocko
2016-08-04 18:46 ` Mikulas Patocka
2016-07-27 21:36 ` NeilBrown
2016-07-19 2:00 ` [RFC PATCH 1/2] mempool: do not consume memory reserves from the reclaim path David Rientjes
2016-07-19 7:49 ` Michal Hocko
2016-07-19 13:54 ` Johannes Weiner
2016-07-19 14:19 ` Michal Hocko
2016-07-19 22:01 ` Mikulas Patocka
2016-07-19 20:45 ` David Rientjes
2016-07-20 8:15 ` Michal Hocko
2016-07-20 21:06 ` David Rientjes
2016-07-21 8:52 ` Michal Hocko
2016-07-21 12:13 ` Johannes Weiner
2016-07-21 14:53 ` Michal Hocko
2016-07-21 15:26 ` Johannes Weiner
2016-07-22 1:41 ` NeilBrown
2016-07-22 6:37 ` Michal Hocko
2016-07-22 12:26 ` Vlastimil Babka
2016-07-22 19:44 ` Andrew Morton
2016-07-23 18:52 ` Vlastimil Babka
2016-07-19 21:50 ` Mikulas Patocka
2016-07-20 6:44 ` Michal Hocko
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