From: Linus Torvalds <torvalds@linux-foundation.org>
To: Mel Gorman <mel@csn.ul.ie>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Minchan Kim <minchan.kim@gmail.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Christoph Lameter <cl@linux.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Rik van Riel <riel@redhat.com>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 2/2] mm,migration: Fix race between shift_arg_pages and rmap_walk by guaranteeing rmap_walk finds PTEs created within the temporary stack
Date: Thu, 6 May 2010 18:40:39 -0700 (PDT) [thread overview]
Message-ID: <alpine.LFD.2.00.1005061836110.901@i5.linux-foundation.org> (raw)
In-Reply-To: <1273188053-26029-3-git-send-email-mel@csn.ul.ie>
On Fri, 7 May 2010, Mel Gorman wrote:
>
> Page migration requires rmap to be able to find all migration ptes
> created by migration. If the second rmap_walk clearing migration PTEs
> misses an entry, it is left dangling causing a BUG_ON to trigger during
> fault. For example;
So I still absolutely detest this patch.
Why didn't the other - much simpler - patch work? The one Rik pointed to:
http://lkml.org/lkml/2010/4/30/198
and didn't do that _disgusting_ temporary anon_vma?
Alternatively, why don't we just take the anon_vma lock over this region,
so that rmap can't _walk_ the damn thing?
Linus
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next prev parent reply other threads:[~2010-05-07 1:43 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-06 23:20 [PATCH 0/2] Fix migration races in rmap_walk() V7 Mel Gorman
2010-05-06 23:20 ` [PATCH 1/2] mm,migration: Prevent rmap_walk_[anon|ksm] seeing the wrong VMA information Mel Gorman
2010-05-07 0:56 ` KAMEZAWA Hiroyuki
2010-05-07 16:26 ` Mel Gorman
2010-05-08 15:39 ` Andrea Arcangeli
2010-05-08 17:02 ` Linus Torvalds
2010-05-08 18:04 ` Andrea Arcangeli
2010-05-08 19:51 ` Linus Torvalds
2010-05-09 19:23 ` Mel Gorman
2010-05-06 23:20 ` [PATCH 2/2] mm,migration: Fix race between shift_arg_pages and rmap_walk by guaranteeing rmap_walk finds PTEs created within the temporary stack Mel Gorman
2010-05-07 1:40 ` Linus Torvalds [this message]
2010-05-07 1:57 ` KAMEZAWA Hiroyuki
2010-05-07 2:12 ` Linus Torvalds
2010-05-07 4:19 ` KAMEZAWA Hiroyuki
2010-05-07 14:18 ` Linus Torvalds
2010-05-09 19:21 ` Mel Gorman
2010-05-09 19:56 ` Linus Torvalds
2010-05-09 20:06 ` Linus Torvalds
2010-05-09 20:20 ` Linus Torvalds
2010-05-10 0:40 ` KAMEZAWA Hiroyuki
2010-05-10 1:30 ` Linus Torvalds
2010-05-10 1:32 ` Linus Torvalds
2010-05-10 1:40 ` KAMEZAWA Hiroyuki
2010-05-10 1:49 ` Linus Torvalds
2010-05-10 13:24 ` Mel Gorman
2010-05-10 23:55 ` KAMEZAWA Hiroyuki
2010-05-10 0:42 ` KAMEZAWA Hiroyuki
2010-05-10 14:02 ` Mel Gorman
2010-05-10 13:49 ` Mel Gorman
2010-05-10 0:32 ` KAMEZAWA Hiroyuki
2010-05-07 9:16 ` Mel Gorman
2010-05-07 8:13 ` [PATCH 0/2] Fix migration races in rmap_walk() V7 KAMEZAWA Hiroyuki
-- strict thread matches above, loose matches on Subject: below --
2010-05-06 15:33 [PATCH 0/2] Fix migration races in rmap_walk() V6 Mel Gorman
2010-05-06 15:33 ` [PATCH 2/2] mm,migration: Fix race between shift_arg_pages and rmap_walk by guaranteeing rmap_walk finds PTEs created within the temporary stack Mel Gorman
2010-05-05 13:14 [PATCH 0/2] Fix migration races in rmap_walk() V5 Mel Gorman
2010-05-05 13:14 ` [PATCH 2/2] mm,migration: Fix race between shift_arg_pages and rmap_walk by guaranteeing rmap_walk finds PTEs created within the temporary stack Mel Gorman
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