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From: Michal Hocko <mhocko@suse.cz>
To: Hugh Dickins <hughd@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	Mel Gorman <mgorman@suse.de>, Minchan Kim <minchan@kernel.org>,
	Rik van Riel <riel@redhat.com>, Ying Han <yinghan@google.com>,
	Greg Thelen <gthelen@google.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Fengguang Wu <fengguang.wu@intel.com>
Subject: Re: [PATCH mmotm] memcg: further prevent OOM with too many dirty pages
Date: Tue, 17 Jul 2012 08:33:01 +0200	[thread overview]
Message-ID: <20120717063301.GA25435@tiehlicka.suse.cz> (raw)
In-Reply-To: <alpine.LSU.2.00.1207162135590.19938@eggly.anvils>

On Mon 16-07-12 21:52:51, Hugh Dickins wrote:
> On Mon, 16 Jul 2012, Michal Hocko wrote:
> > On Mon 16-07-12 01:35:34, Hugh Dickins wrote:
> > > But even so, the test still OOMs sometimes: when originally testing
> > > on 3.5-rc6, it OOMed about one time in five or ten; when testing
> > > just now on 3.5-rc6-mm1, it OOMed on the first iteration.
> > > 
> > > This residual problem comes from an accumulation of pages under
> > > ordinary writeback, not marked PageReclaim, so rightly not causing
> > > the memcg check to wait on their writeback: these too can prevent
> > > shrink_page_list() from freeing any pages, so many times that memcg
> > > reclaim fails and OOMs.
> > 
> > I guess you managed to trigger this with 20M limit, right?
> 
> That's right.
> 
> > I have tested
> > with different group sizes but the writeback didn't trigger for most of
> > them and all the dirty data were flushed from the reclaim.
> 
> I didn't examine writeback stats to confirm, but I guess that just
> occasionally it managed to come in and do enough work to confound us.
> 
> > Have you used any special setting the dirty ratio?
> 
> No, I wasn't imaginative enough to try that.
> 
> > Or was it with xfs (IIUC that one
> > does ignore writeback from the direct reclaim completely).
> 
> No, just ext4 at that point.
> 
> I have since tested the final patch with ext4, ext3 (by ext3 driver
> and by ext4 driver), ext2 (by ext2 driver and by ext4 driver), xfs,
> btrfs, vfat, tmpfs (with swap on the USB stick) and block device:
> about an hour on each, no surprises, all okay.
> 
> But I didn't experiment beyond the 20M memcg.

Great coverage anyway. Thanks a lot Hugh!

> 
> Hugh

-- 
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9    
Czech Republic

WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@suse.cz>
To: Hugh Dickins <hughd@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	Mel Gorman <mgorman@suse.de>, Minchan Kim <minchan@kernel.org>,
	Rik van Riel <riel@redhat.com>, Ying Han <yinghan@google.com>,
	Greg Thelen <gthelen@google.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Fengguang Wu <fengguang.wu@intel.com>
Subject: Re: [PATCH mmotm] memcg: further prevent OOM with too many dirty pages
Date: Tue, 17 Jul 2012 08:33:01 +0200	[thread overview]
Message-ID: <20120717063301.GA25435@tiehlicka.suse.cz> (raw)
In-Reply-To: <alpine.LSU.2.00.1207162135590.19938@eggly.anvils>

On Mon 16-07-12 21:52:51, Hugh Dickins wrote:
> On Mon, 16 Jul 2012, Michal Hocko wrote:
> > On Mon 16-07-12 01:35:34, Hugh Dickins wrote:
> > > But even so, the test still OOMs sometimes: when originally testing
> > > on 3.5-rc6, it OOMed about one time in five or ten; when testing
> > > just now on 3.5-rc6-mm1, it OOMed on the first iteration.
> > > 
> > > This residual problem comes from an accumulation of pages under
> > > ordinary writeback, not marked PageReclaim, so rightly not causing
> > > the memcg check to wait on their writeback: these too can prevent
> > > shrink_page_list() from freeing any pages, so many times that memcg
> > > reclaim fails and OOMs.
> > 
> > I guess you managed to trigger this with 20M limit, right?
> 
> That's right.
> 
> > I have tested
> > with different group sizes but the writeback didn't trigger for most of
> > them and all the dirty data were flushed from the reclaim.
> 
> I didn't examine writeback stats to confirm, but I guess that just
> occasionally it managed to come in and do enough work to confound us.
> 
> > Have you used any special setting the dirty ratio?
> 
> No, I wasn't imaginative enough to try that.
> 
> > Or was it with xfs (IIUC that one
> > does ignore writeback from the direct reclaim completely).
> 
> No, just ext4 at that point.
> 
> I have since tested the final patch with ext4, ext3 (by ext3 driver
> and by ext4 driver), ext2 (by ext2 driver and by ext4 driver), xfs,
> btrfs, vfat, tmpfs (with swap on the USB stick) and block device:
> about an hour on each, no surprises, all okay.
> 
> But I didn't experiment beyond the 20M memcg.

Great coverage anyway. Thanks a lot Hugh!

> 
> Hugh

-- 
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9    
Czech Republic

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  reply	other threads:[~2012-07-17  6:33 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-06-19 14:50 [PATCH -mm] memcg: prevent from OOM with too many dirty pages Michal Hocko
2012-06-19 14:50 ` Michal Hocko
2012-06-19 22:00 ` Andrew Morton
2012-06-19 22:00   ` Andrew Morton
2012-06-20  8:27   ` Michal Hocko
2012-06-20  8:27     ` Michal Hocko
2012-06-20  9:20   ` Mel Gorman
2012-06-20  9:20     ` Mel Gorman
2012-06-20  9:55     ` Fengguang Wu
2012-06-20  9:55       ` Fengguang Wu
2012-06-20  9:59     ` Michal Hocko
2012-06-20  9:59       ` Michal Hocko
2012-06-20 10:11   ` [PATCH v2 " Michal Hocko
2012-06-20 10:11     ` Michal Hocko
2012-07-12  1:57     ` Hugh Dickins
2012-07-12  1:57       ` Hugh Dickins
2012-07-12  2:21       ` Andrew Morton
2012-07-12  2:21         ` Andrew Morton
2012-07-12  3:13         ` Hugh Dickins
2012-07-12  3:13           ` Hugh Dickins
2012-07-12  7:05       ` Michal Hocko
2012-07-12  7:05         ` Michal Hocko
2012-07-12 21:13         ` Andrew Morton
2012-07-12 21:13           ` Andrew Morton
2012-07-12 22:42           ` Hugh Dickins
2012-07-12 22:42             ` Hugh Dickins
2012-07-13  8:21             ` Michal Hocko
2012-07-13  8:21               ` Michal Hocko
2012-07-16  8:30               ` Hugh Dickins
2012-07-16  8:30                 ` Hugh Dickins
2012-07-16  8:35                 ` [PATCH mmotm] memcg: further prevent " Hugh Dickins
2012-07-16  8:35                   ` Hugh Dickins
2012-07-16  9:26                   ` Michal Hocko
2012-07-16  9:26                     ` Michal Hocko
2012-07-17  4:52                     ` Hugh Dickins
2012-07-17  4:52                       ` Hugh Dickins
2012-07-17  6:33                       ` Michal Hocko [this message]
2012-07-17  6:33                         ` Michal Hocko
2012-07-16 21:08                   ` Andrew Morton
2012-07-16 21:08                     ` Andrew Morton
2012-07-16  8:10         ` [PATCH v2 -mm] memcg: prevent from " Hugh Dickins
2012-07-16  8:10           ` Hugh Dickins
2012-07-16  8:48           ` Michal Hocko
2012-07-16  8:48             ` Michal Hocko

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