From: Linus Torvalds <torvalds@linux-foundation.org>
To: Minchan Kim <minchan.kim@gmail.com>
Cc: Mel Gorman <mel@csn.ul.ie>,
Andrew Morton <akpm@linux-foundation.org>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Christoph Lameter <cl@linux.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Rik van Riel <riel@redhat.com>
Subject: Re: [PATCH 1/2] mm,migration: Prevent rmap_walk_[anon|ksm] seeing the wrong VMA information
Date: Thu, 6 May 2010 07:06:08 -0700 (PDT) [thread overview]
Message-ID: <alpine.LFD.2.00.1005060703540.901@i5.linux-foundation.org> (raw)
In-Reply-To: <p2s28c262361005060247m2983625clff01aeaa1668402f@mail.gmail.com>
On Thu, 6 May 2010, Minchan Kim wrote:
> > + A A A A */
> > + A A A avc = list_first_entry(&anon_vma->head, struct anon_vma_chain, same_anon_vma);
>
> Dumb question.
>
> I can't understand why we should use list_first_entry.
It's not that we "should" use list_entry_first. It's that we want to find
_any_ entry on the list, and the most natural one is the first one.
So we could take absolutely any 'avc' entry that is reachable from the
anon_vma, and use that to look up _any_ 'vma' that is associated with that
anon_vma. And then, from _any_ of those vma's, we know how to get to the
"root anon_vma" - the one that they are all associated with.
So no, there's absolutely nothing special about the first entry. It's
just a random easily found one.
Linus
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next prev parent reply other threads:[~2010-05-06 14:08 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-05 13:14 [PATCH 0/2] Fix migration races in rmap_walk() V5 Mel Gorman
2010-05-05 13:14 ` [PATCH 1/2] mm,migration: Prevent rmap_walk_[anon|ksm] seeing the wrong VMA information Mel Gorman
2010-05-05 14:34 ` Linus Torvalds
2010-05-05 14:56 ` Mel Gorman
2010-05-05 15:31 ` Linus Torvalds
2010-05-05 15:54 ` Mel Gorman
2010-05-05 16:13 ` Andrea Arcangeli
2010-05-05 19:11 ` Peter Zijlstra
2010-05-05 19:57 ` Andrea Arcangeli
2010-05-21 0:27 ` Andrea Arcangeli
2010-05-06 10:37 ` Mel Gorman
2010-05-05 17:34 ` Linus Torvalds
2010-05-05 17:57 ` Linus Torvalds
2010-05-05 18:14 ` Mel Gorman
2010-05-05 18:34 ` Linus Torvalds
2010-05-06 11:03 ` Mel Gorman
2010-05-06 13:40 ` Rik van Riel
2010-05-06 13:45 ` Mel Gorman
2010-05-05 17:53 ` Mel Gorman
2010-05-05 18:02 ` Linus Torvalds
2010-05-05 18:17 ` Mel Gorman
2010-05-06 0:22 ` Mel Gorman
2010-05-06 0:42 ` Linus Torvalds
2010-05-06 10:02 ` Mel Gorman
2010-05-06 14:15 ` Linus Torvalds
2010-05-06 14:25 ` Mel Gorman
2010-05-06 9:47 ` Minchan Kim
2010-05-06 9:54 ` Mel Gorman
2010-05-06 10:01 ` Minchan Kim
2010-05-06 10:10 ` Mel Gorman
2010-05-06 14:06 ` Linus Torvalds [this message]
2010-05-06 15:59 ` Minchan Kim
2010-05-06 7:38 ` KAMEZAWA Hiroyuki
2010-05-06 9:46 ` Mel Gorman
2010-05-06 23:52 ` KAMEZAWA Hiroyuki
2010-05-07 5:49 ` KAMEZAWA Hiroyuki
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
2010-05-06 15:33 [PATCH 0/2] Fix migration races in rmap_walk() V6 Mel Gorman
2010-05-06 15:33 ` [PATCH 1/2] mm,migration: Prevent rmap_walk_[anon|ksm] seeing the wrong VMA information Mel Gorman
2010-05-06 15:44 ` Rik van Riel
2010-05-06 15:51 ` Mel Gorman
2010-05-06 15:59 ` Linus Torvalds
2010-05-06 17:07 ` Mel Gorman
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
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