From: Michal Hocko <mhocko@kernel.org>
To: Mel Gorman <mgorman@suse.de>
Cc: Nils Holland <nholland@tisys.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Chris Mason <clm@fb.com>, David Sterba <dsterba@suse.cz>,
linux-btrfs@vger.kernel.org
Subject: Re: [RFC PATCH] mm, memcg: fix (Re: OOM: Better, but still there on)
Date: Fri, 30 Dec 2016 12:05:45 +0100 [thread overview]
Message-ID: <20161230110545.GF13301@dhcp22.suse.cz> (raw)
In-Reply-To: <20161230101926.jjjw76negqcvyaim@suse.de>
On Fri 30-12-16 10:19:26, Mel Gorman wrote:
> On Mon, Dec 26, 2016 at 01:48:40PM +0100, Michal Hocko wrote:
> > On Fri 23-12-16 23:26:00, Nils Holland wrote:
> > > On Fri, Dec 23, 2016 at 03:47:39PM +0100, Michal Hocko wrote:
> > > >
> > > > Nils, even though this is still highly experimental, could you give it a
> > > > try please?
> > >
> > > Yes, no problem! So I kept the very first patch you sent but had to
> > > revert the latest version of the debugging patch (the one in
> > > which you added the "mm_vmscan_inactive_list_is_low" event) because
> > > otherwise the patch you just sent wouldn't apply. Then I rebooted with
> > > memory cgroups enabled again, and the first thing that strikes the eye
> > > is that I get this during boot:
> > >
> > > [ 1.568174] ------------[ cut here ]------------
> > > [ 1.568327] WARNING: CPU: 0 PID: 1 at mm/memcontrol.c:1032 mem_cgroup_update_lru_size+0x118/0x130
> > > [ 1.568543] mem_cgroup_update_lru_size(f4406400, 2, 1): lru_size 0 but not empty
> >
> > Ohh, I can see what is wrong! a) there is a bug in the accounting in
> > my patch (I double account) and b) the detection for the empty list
> > cannot work after my change because per node zone will not match per
> > zone statistics. The updated patch is below. So I hope my brain already
> > works after it's been mostly off last few days...
> > ---
> > From 397adf46917b2d9493180354a7b0182aee280a8b Mon Sep 17 00:00:00 2001
> > From: Michal Hocko <mhocko@suse.com>
> > Date: Fri, 23 Dec 2016 15:11:54 +0100
> > Subject: [PATCH] mm, memcg: fix the active list aging for lowmem requests when
> > memcg is enabled
> >
> > Nils Holland has reported unexpected OOM killer invocations with 32b
> > kernel starting with 4.8 kernels
> >
>
> I think it's unfortunate that per-zone stats are reintroduced to the
> memcg structure.
the original patch I had didn't add per zone stats but rather did a
nr_highmem counter to mem_cgroup_per_node (inside ifdeff CONFIG_HIGMEM).
This would help for this particular case but it wouldn't work for other
lowmem requests (e.g. GFP_DMA32) and with the kmem accounting this might
be a problem in future. So I've decided to go with a more generic
approach which requires per-zone tracking. I cannot say I would be
overly happy about this at all.
> I can't help but think that it would have also worked
> to always rotate a small number of pages if !inactive_list_is_low and
> reclaiming for memcg even if it distorted page aging.
I am not really sure how that would work. Do you mean something like the
following?
diff --git a/mm/vmscan.c b/mm/vmscan.c
index fa30010a5277..563ada3c02ac 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2044,6 +2044,9 @@ static bool inactive_list_is_low(struct lruvec *lruvec, bool file,
inactive = lruvec_lru_size(lruvec, file * LRU_FILE);
active = lruvec_lru_size(lruvec, file * LRU_FILE + LRU_ACTIVE);
+ if (!mem_cgroup_disabled())
+ goto out;
+
/*
* For zone-constrained allocations, it is necessary to check if
* deactivations are required for lowmem to be reclaimed. This
@@ -2063,6 +2066,7 @@ static bool inactive_list_is_low(struct lruvec *lruvec, bool file,
active -= min(active, active_zone);
}
+out:
gb = (inactive + active) >> (30 - PAGE_SHIFT);
if (gb)
inactive_ratio = int_sqrt(10 * gb);
The problem I see with such an approach is that chances are that this
would reintroduce what f8d1a31163fc ("mm: consider whether to decivate
based on eligible zones inactive ratio") tried to fix. But maybe I have
missed your point.
> However, given that such an approach would be less robust and this has
> been heavily tested;
>
> Acked-by: Mel Gorman <mgorman@suse.de>
Thanks!
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2016-12-30 11:05 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20161215225702.GA27944@boerne.fritz.box>
2016-12-16 7:39 ` OOM: Better, but still there on 4.9 Michal Hocko
2016-12-16 15:58 ` OOM: Better, but still there on Michal Hocko
2016-12-16 15:58 ` [PATCH 1/2] mm: consolidate GFP_NOFAIL checks in the allocator slowpath Michal Hocko
2016-12-16 15:58 ` [PATCH 2/2] mm, oom: do not enfore OOM killer for __GFP_NOFAIL automatically Michal Hocko
2016-12-16 17:31 ` Johannes Weiner
2016-12-16 22:12 ` Michal Hocko
2016-12-17 11:17 ` Tetsuo Handa
2016-12-18 16:37 ` Michal Hocko
2016-12-16 18:47 ` OOM: Better, but still there on Nils Holland
2016-12-17 0:02 ` Michal Hocko
2016-12-17 12:59 ` Nils Holland
2016-12-17 14:44 ` Tetsuo Handa
2016-12-17 17:11 ` Nils Holland
2016-12-17 21:06 ` Nils Holland
2016-12-18 5:14 ` Tetsuo Handa
2016-12-19 13:45 ` Michal Hocko
2016-12-20 2:08 ` Nils Holland
2016-12-21 7:36 ` Michal Hocko
2016-12-21 11:00 ` Tetsuo Handa
2016-12-21 11:16 ` Michal Hocko
2016-12-21 14:04 ` Chris Mason
2016-12-22 10:10 ` Nils Holland
2016-12-22 10:27 ` Michal Hocko
2016-12-22 10:35 ` Nils Holland
2016-12-22 10:46 ` Tetsuo Handa
2016-12-22 19:17 ` Michal Hocko
2016-12-22 21:46 ` Nils Holland
2016-12-23 10:51 ` Michal Hocko
2016-12-23 12:18 ` Nils Holland
2016-12-23 12:57 ` Michal Hocko
2016-12-23 14:47 ` [RFC PATCH] mm, memcg: fix (Re: OOM: Better, but still there on) Michal Hocko
2016-12-23 22:26 ` Nils Holland
2016-12-26 12:48 ` Michal Hocko
2016-12-26 18:57 ` Nils Holland
2016-12-27 8:08 ` Michal Hocko
2016-12-27 11:23 ` Nils Holland
2016-12-27 11:27 ` Michal Hocko
2016-12-27 15:55 ` Michal Hocko
2016-12-27 16:28 ` [PATCH] mm, vmscan: consider eligible zones in get_scan_count kbuild test robot
2016-12-28 8:51 ` Michal Hocko
2016-12-27 19:33 ` [RFC PATCH] mm, memcg: fix (Re: OOM: Better, but still there on) Nils Holland
2016-12-28 8:57 ` Michal Hocko
2016-12-29 1:20 ` Minchan Kim
2016-12-29 9:04 ` Michal Hocko
2016-12-30 2:05 ` Minchan Kim
2016-12-30 10:40 ` Michal Hocko
2016-12-29 0:31 ` Minchan Kim
2016-12-29 0:48 ` Minchan Kim
2016-12-29 8:52 ` Michal Hocko
2016-12-30 10:19 ` Mel Gorman
2016-12-30 11:05 ` Michal Hocko [this message]
2016-12-30 12:43 ` Mel Gorman
2016-12-25 22:25 ` [lkp-developer] [mm, memcg] d18e2b2aca: WARNING:at_mm/memcontrol.c:#mem_cgroup_update_lru_size kernel test robot
2016-12-26 12:26 ` Michal Hocko
2016-12-26 12:50 ` Michal Hocko
2016-12-16 18:15 ` OOM: Better, but still there on 4.9 Chris Mason
2016-12-16 22:14 ` Michal Hocko
2016-12-16 22:47 ` Chris Mason
2016-12-16 23:31 ` Michal Hocko
2016-12-16 19:50 ` Chris Mason
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