From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: Minchan Kim <minchan.kim@gmail.com>
Cc: Mel Gorman <mel@csn.ul.ie>,
Christoph Lameter <cl@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
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: Thu, 22 Apr 2010 19:31:06 +0900 [thread overview]
Message-ID: <20100422193106.9ffad4ec.kamezawa.hiroyu@jp.fujitsu.com> (raw)
In-Reply-To: <x2l28c262361004220313q76752366l929a8959cd6d6862@mail.gmail.com>
On Thu, 22 Apr 2010 19:13:12 +0900
Minchan Kim <minchan.kim@gmail.com> wrote:
> On Thu, Apr 22, 2010 at 6:46 PM, KAMEZAWA Hiroyuki
> <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> > Hmm..in my test, the case was.
> >
> > Before try_to_unmap:
> > A A A A mapcount=1, SwapCache, remap_swapcache=1
> > After remap
> > A A A A mapcount=0, SwapCache, rc=0.
> >
> > So, I think there may be some race in rmap_walk() and vma handling or
> > anon_vma handling. migration_entry isn't found by rmap_walk.
> >
> > Hmm..it seems this kind patch will be required for debug.
>
> I looked do_swap_page, again.
> lock_page is called long after migration_entry_wait.
> It means lock_page can't close the race.
>
> So I think this BUG is possible.
> What do you think?
>
I think it's not a problem.
When migration-entry-wait is called, enry_wait() does
pte_lock();
check migration_pte
check it's locked.
And after wait_on_page_locked(), it just returns to user and cause
page fault again.
Thanks,
-Kame
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next prev parent reply other threads:[~2010-04-22 10:35 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 [this message]
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
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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