From: Rik van Riel <riel@redhat.com>
To: Mel Gorman <mel@csn.ul.ie>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Minchan Kim <minchan.kim@gmail.com>,
Linux-MM <linux-mm@kvack.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
LKML <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 4/5] always lock the root (oldest) anon_vma
Date: Wed, 12 May 2010 17:08:11 -0400 [thread overview]
Message-ID: <4BEB18BB.5010803@redhat.com> (raw)
In-Reply-To: <20100512210216.GP24989@csn.ul.ie>
On 05/12/2010 05:02 PM, Mel Gorman wrote:
> This last comment is a bit light. It's actually restoring the lock that
> was taken in 2.6.33 to some extent except we are always taking it now.
> In 2.6.33, it was resricted to
>
> if (vma->anon_vma&& (insert || importer || start != vma->vm_start))
> anon_vma = vma->anon_vma;
>
> but now it's always. Has it been determined that the locking in 2.6.33
> was insufficient or are we playing it safe now?
Playing it safe, mostly.
Another aspect is that, if you look at the if condition above,
the number of cases where we have an anon_vma and do not take
the lock is pretty small.
Basically only the case where we expand a VMA upward or merge
VMAs in an mprotect. I believe in pretty much all other cases
we end up needing to take the lock.
I am not entirely convinced the old code took the lock in all
of the required cases.
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next prev parent reply other threads:[~2010-05-12 21:08 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-12 17:38 [PATCH 0/5] always lock the root anon_vma Rik van Riel
2010-05-12 17:39 ` [PATCH 1/5] rename anon_vma_lock to vma_lock_anon_vma Rik van Riel
2010-05-12 20:57 ` Mel Gorman
2010-05-13 0:30 ` KAMEZAWA Hiroyuki
2010-05-12 17:39 ` [PATCH 3/5] track the root (oldest) anon_vma Rik van Riel
2010-05-12 20:59 ` Mel Gorman
2010-05-12 21:01 ` Rik van Riel
2010-05-13 0:38 ` KAMEZAWA Hiroyuki
2010-05-13 2:25 ` Rik van Riel
2010-05-14 0:04 ` KAMEZAWA Hiroyuki
2010-05-12 17:40 ` [PATCH 4/5] always lock " Rik van Riel
2010-05-12 21:02 ` Mel Gorman
2010-05-12 21:08 ` Rik van Riel [this message]
2010-05-13 9:54 ` Mel Gorman
2010-05-13 14:33 ` [PATCH -v2 " Rik van Riel
2010-05-13 21:09 ` Andrew Morton
2010-05-13 22:50 ` Rik van Riel
2010-05-14 9:33 ` Mel Gorman
2010-05-26 4:00 ` Rik van Riel
2010-05-26 4:15 ` Andrew Morton
2010-05-26 5:46 ` james toy
2010-06-01 0:57 ` james toy
2010-05-26 15:24 ` [PATCH -v2 0/5] always lock the root anon_vma Rik van Riel
2010-05-26 15:25 ` [PATCH 1/5] rename anon_vma_lock to vma_lock_anon_vma Rik van Riel
2010-05-26 17:25 ` Linus Torvalds
2010-05-26 19:01 ` Rik van Riel
2010-05-26 19:25 ` Linus Torvalds
2010-05-26 19:35 ` Rik van Riel
2010-05-26 15:25 ` [PATCH 2/5] change direct call of spin_lock(anon_vma->lock) to inline function Rik van Riel
2010-05-26 15:26 ` [PATCH 3/5] track the root (oldest) anon_vma Rik van Riel
2010-05-26 15:27 ` [PATCH 4/5] always lock " Rik van Riel
2010-05-26 15:27 ` [PATCH 5/5] extend KSM refcounts to the anon_vma root Rik van Riel
2010-05-12 21:55 ` [PATCH 4/5] always lock the root (oldest) anon_vma Linus Torvalds
2010-05-12 22:18 ` Rik van Riel
2010-05-12 22:26 ` Linus Torvalds
2010-05-12 17:41 ` [PATCH 5/5] extend KSM refcounts to the anon_vma root Rik van Riel
2010-05-12 21:07 ` Mel Gorman
2010-05-12 21:09 ` Rik van Riel
2010-05-13 11:26 ` Mel Gorman
2010-05-13 13:11 ` Rik van Riel
2010-05-13 13:24 ` Mel Gorman
2010-05-13 14:34 ` [PATCH -v2 " Rik van Riel
2010-05-19 1:05 ` Andrea Arcangeli
2010-05-12 17:41 ` [PATCH 2/5] change direct call of spin_lock(anon_vma->lock) to inline function Rik van Riel
2010-05-12 20:58 ` Mel Gorman
2010-05-13 0:32 ` KAMEZAWA Hiroyuki
2010-05-20 22:42 ` [PATCH 6/5] adjust mm_take_all_locks to anon-vma-root locking Andrea Arcangeli
2010-05-20 23:07 ` Rik van Riel
-- strict thread matches above, loose matches on Subject: below --
2010-05-26 19:38 [PATCH -v3 0/5] always lock the root anon_vma Rik van Riel
2010-05-26 19:40 ` [PATCH 4/5] always lock the root (oldest) anon_vma Rik van Riel
2010-05-26 20:36 ` Larry Woodman
2010-05-27 0:57 ` KAMEZAWA Hiroyuki
2010-05-27 13:55 ` Minchan Kim
2010-05-27 17:48 ` Mel Gorman
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