From: Christoph Lameter <cl@linux-foundation.org>
To: Mel Gorman <mel@csn.ul.ie>
Cc: 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>,
Minchan Kim <minchan.kim@gmail.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.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: Wed, 21 Apr 2010 10:31:29 -0500 (CDT) [thread overview]
Message-ID: <alpine.DEB.2.00.1004211027120.4959@router.home> (raw)
In-Reply-To: <20100421151417.GK30306@csn.ul.ie>
On Wed, 21 Apr 2010, Mel Gorman wrote:
> On Wed, Apr 21, 2010 at 10:05:21AM -0500, Christoph Lameter wrote:
> > On Wed, 21 Apr 2010, Mel Gorman wrote:
> >
> > > No, remap_swapcache could just be called "remap". If it's 0, it's
> > > considered unsafe to remap the page.
> >
> > Call this "can_remap"?
> >
>
> can_do - ba dum tisch.
>
> While you are looking though, maybe you can confirm something for me.
>
> 1. Is leaving a migration PTE like this behind reasonable? (I think yes
> particularly as the page was already unmapped so it's not a new fault
> incurred)
The design of page migration only allows for the existence of these as
long as the page is locked. Not sure what would happen if you leave this
hanging around. Paths that are not prepared for a migration_pte may
encounter one.
> 2. Is the BUG_ON check in
> include/linux/swapops.h#migration_entry_to_page() now wrong? (I
> think yes, but I'm not sure and I'm having trouble verifying it)
The bug check ensures that migration entries only occur when the page
is locked. This patch changes that behavior. This is going too oops
therefore in unmap_and_move() when you try to remove the migration_ptes
from an unlocked page.
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next prev parent reply other threads:[~2010-04-21 16:21 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 [this message]
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
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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