From: Andrea Arcangeli <aarcange@redhat.com>
To: Mel Gorman <mel@csn.ul.ie>
Cc: Minchan Kim <minchan.kim@gmail.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Christoph Lameter <cl@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Adam Litke <agl@us.ibm.com>, Avi Kivity <avi@redhat.com>,
David Rientjes <rientjes@google.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Rik van Riel <riel@redhat.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 04/14] mm,migration: Allow the migration of PageSwapCache pages
Date: Fri, 23 Apr 2010 23:35:49 +0200 [thread overview]
Message-ID: <20100423213549.GV32034@random.random> (raw)
In-Reply-To: <20100423193948.GU32034@random.random>
On Fri, Apr 23, 2010 at 09:39:48PM +0200, Andrea Arcangeli wrote:
> On Fri, Apr 23, 2010 at 08:23:12PM +0100, Mel Gorman wrote:
> > On Fri, Apr 23, 2010 at 08:31:35PM +0200, Andrea Arcangeli wrote:
> > > Hi Mel,
> > >
> > > On Thu, Apr 22, 2010 at 04:44:43PM +0100, Mel Gorman wrote:
> > > > heh, I thought of a similar approach at the same time as you but missed
> > > > this mail until later. However, with this approach I suspect there is a
> > > > possibility that two walkers of the same anon_vma list could livelock if
> > > > two locks on the list are held at the same time. Am still thinking of
> > > > how it could be resolved without introducing new locking.
> > >
> > > Trying to understand this issue and I've some questions. This
> > > vma_adjust and lock inversion troubles with the anon-vma lock in
> > > rmap_walk are a new issue introduced by the recent anon-vma changes,
> > > right?
> > >
> >
> > In a manner of speaking. There was no locking going on but prior to the
> > anon_vma changes, there would have been only one anon_vma lock and the
> > fix would be easier - just take the lock on anon_vma->lock while the
> > VMAs are being updated.
>
> So it was very much a bug before too and we could miss to find some
> pte mapping the page if vm_start was adjusted?
Well I looked deeper into it myself as I wanted to have this bit (and
other bits) sorted out in aa.git, and definitely this is a bug
introduced by the newest anon-vma changes in 2.6.34-rc so aa.git
cannot be affected as it's using the 2.6.33 anon-vma (and prev) code.
vma_adjust already takes the anon_vma->lock and of course I also
further verified that trying to apply your snippet to vma_adjust
results in immediately deadlock as the very same lock is already taken
in my tree as it's the same anon-vma (simpler). So aa.git will be
immune from these bugs for now.
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next prev parent reply other threads:[~2010-04-23 21:36 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-20 21:01 [PATCH 0/14] Memory Compaction v8 Mel Gorman
2010-04-20 21:01 ` [PATCH 01/14] mm,migration: Take a reference to the anon_vma before migrating Mel Gorman
2010-04-21 2:49 ` KAMEZAWA Hiroyuki
2010-04-20 21:01 ` [PATCH 02/14] mm,migration: Share the anon_vma ref counts between KSM and page migration Mel Gorman
2010-04-20 21:01 ` [PATCH 03/14] mm,migration: Do not try to migrate unmapped anonymous pages Mel Gorman
2010-04-20 21:01 ` [PATCH 04/14] mm,migration: Allow the migration of PageSwapCache pages Mel Gorman
2010-04-21 14:30 ` Christoph Lameter
2010-04-21 15:00 ` Mel Gorman
2010-04-21 15:05 ` Christoph Lameter
2010-04-21 15:14 ` Mel Gorman
2010-04-21 15:31 ` Christoph Lameter
2010-04-21 15:34 ` Mel Gorman
2010-04-21 15:46 ` Christoph Lameter
2010-04-22 9:28 ` Mel Gorman
2010-04-22 9:46 ` KAMEZAWA Hiroyuki
2010-04-22 10:13 ` Minchan Kim
2010-04-22 10:31 ` KAMEZAWA Hiroyuki
2010-04-22 10:51 ` KAMEZAWA Hiroyuki
2010-04-22 14:14 ` Mel Gorman
2010-04-22 14:18 ` Minchan Kim
2010-04-22 15:40 ` Mel Gorman
2010-04-22 16:13 ` Mel Gorman
2010-04-22 19:29 ` Mel Gorman
2010-04-22 19:40 ` Christoph Lameter
2010-04-22 23:52 ` KAMEZAWA Hiroyuki
2010-04-23 9:03 ` Mel Gorman
2010-04-22 14:23 ` Minchan Kim
2010-04-22 14:40 ` Minchan Kim
2010-04-22 15:44 ` Mel Gorman
2010-04-23 18:31 ` Andrea Arcangeli
2010-04-23 19:23 ` Mel Gorman
2010-04-23 19:39 ` Andrea Arcangeli
2010-04-23 21:35 ` Andrea Arcangeli [this message]
2010-04-24 10:52 ` Mel Gorman
2010-04-24 11:13 ` Andrea Arcangeli
2010-04-24 11:59 ` Mel Gorman
2010-04-24 14:30 ` Andrea Arcangeli
2010-04-26 21:54 ` Rik van Riel
2010-04-26 22:11 ` Mel Gorman
2010-04-26 22:26 ` Andrea Arcangeli
2010-04-25 14:41 ` Andrea Arcangeli
2010-04-27 9:40 ` Mel Gorman
2010-04-27 10:41 ` KAMEZAWA Hiroyuki
2010-04-27 11:12 ` Mel Gorman
2010-04-27 15:42 ` Andrea Arcangeli
2010-04-24 10:50 ` Mel Gorman
2010-04-22 15:14 ` Christoph Lameter
2010-04-23 3:39 ` Paul E. McKenney
2010-04-23 4:55 ` Minchan Kim
2010-04-21 23:59 ` KAMEZAWA Hiroyuki
2010-04-22 0:11 ` Minchan Kim
2010-04-20 21:01 ` [PATCH 05/14] mm: Allow CONFIG_MIGRATION to be set without CONFIG_NUMA or memory hot-remove Mel Gorman
2010-04-20 21:01 ` [PATCH 06/14] mm: Export unusable free space index via debugfs Mel Gorman
2010-04-20 21:01 ` [PATCH 07/14] mm: Export fragmentation " Mel Gorman
2010-04-20 21:01 ` [PATCH 08/14] mm: Move definition for LRU isolation modes to a header Mel Gorman
2010-04-20 21:01 ` [PATCH 09/14] mm,compaction: Memory compaction core Mel Gorman
2010-04-20 21:01 ` [PATCH 10/14] mm,compaction: Add /proc trigger for memory compaction Mel Gorman
2010-04-20 21:01 ` [PATCH 11/14] mm,compaction: Add /sys trigger for per-node " Mel Gorman
2010-04-20 21:01 ` [PATCH 12/14] mm,compaction: Direct compact when a high-order allocation fails Mel Gorman
2010-05-05 12:19 ` [PATCH] fix count_vm_event preempt in memory compaction direct reclaim Andrea Arcangeli
2010-05-05 12:51 ` Mel Gorman
2010-05-05 13:11 ` Andrea Arcangeli
2010-05-05 13:55 ` Mel Gorman
2010-05-05 14:48 ` Andrea Arcangeli
2010-05-05 15:14 ` Mel Gorman
2010-05-05 15:25 ` Andrea Arcangeli
2010-05-05 15:32 ` Mel Gorman
2010-04-20 21:01 ` [PATCH 13/14] mm,compaction: Add a tunable that decides when memory should be compacted and when it should be reclaimed Mel Gorman
2010-04-20 21:01 ` [PATCH 14/14] mm,compaction: Defer compaction using an exponential backoff when compaction fails Mel Gorman
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