From: Rik van Riel <riel@redhat.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: akpm@linux-foundation.org, Mel Gorman <mel@csn.ul.ie>,
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>,
Andrea Arcangeli <aarcange@redhat.com>,
Christoph Lameter <cl@linux.com>
Subject: Re: [PATCH 1/2] mm: Take all anon_vma locks in anon_vma_lock
Date: Mon, 03 May 2010 12:53:50 -0400 [thread overview]
Message-ID: <4BDEFF9E.6080508@redhat.com> (raw)
In-Reply-To: <alpine.LFD.2.00.1005030940490.5478@i5.linux-foundation.org>
On 05/03/2010 12:41 PM, Linus Torvalds wrote:
> On Mon, 3 May 2010, Rik van Riel wrote:
>>
>> Both the page migration code and the transparent hugepage patches expect
>> 100% reliable rmap lookups and use page_lock_anon_vma(page) to prevent
>> races with mmap, munmap, expand_stack, etc.
>
> Pretty much same comments as for the other one. Why are we pandering to
> the case that is/should be unusual?
In this case, because the fix from the migration side is
difficult and fragile, while fixing things from the mmap
side is straightforward.
I believe the overhead of patch 1/2 should be minimal
as well, because the locks we take are the _depth_ of
the process tree (truncated every exec), not the width.
As for patch 2/2, Mel has an alternative approach for that:
http://lkml.org/lkml/2010/4/30/198
Does Mel's patch seem more reasonable to you?
--
All rights reversed
WARNING: multiple messages have this Message-ID (diff)
From: Rik van Riel <riel@redhat.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: akpm@linux-foundation.org, Mel Gorman <mel@csn.ul.ie>,
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>,
Andrea Arcangeli <aarcange@redhat.com>,
Christoph Lameter <cl@linux.com>
Subject: Re: [PATCH 1/2] mm: Take all anon_vma locks in anon_vma_lock
Date: Mon, 03 May 2010 12:53:50 -0400 [thread overview]
Message-ID: <4BDEFF9E.6080508@redhat.com> (raw)
In-Reply-To: <alpine.LFD.2.00.1005030940490.5478@i5.linux-foundation.org>
On 05/03/2010 12:41 PM, Linus Torvalds wrote:
> On Mon, 3 May 2010, Rik van Riel wrote:
>>
>> Both the page migration code and the transparent hugepage patches expect
>> 100% reliable rmap lookups and use page_lock_anon_vma(page) to prevent
>> races with mmap, munmap, expand_stack, etc.
>
> Pretty much same comments as for the other one. Why are we pandering to
> the case that is/should be unusual?
In this case, because the fix from the migration side is
difficult and fragile, while fixing things from the mmap
side is straightforward.
I believe the overhead of patch 1/2 should be minimal
as well, because the locks we take are the _depth_ of
the process tree (truncated every exec), not the width.
As for patch 2/2, Mel has an alternative approach for that:
http://lkml.org/lkml/2010/4/30/198
Does Mel's patch seem more reasonable to you?
--
All rights reversed
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next prev parent reply other threads:[~2010-05-03 16:55 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-03 16:17 [PATCH 0/2] Fix migration races in rmap_walk() V4 Rik van Riel
2010-05-03 16:17 ` Rik van Riel
2010-05-03 16:18 ` [PATCH 1/2] mm: Take all anon_vma locks in anon_vma_lock Rik van Riel
2010-05-03 16:18 ` Rik van Riel
2010-05-03 16:41 ` Linus Torvalds
2010-05-03 16:41 ` Linus Torvalds
2010-05-03 16:53 ` Rik van Riel [this message]
2010-05-03 16:53 ` Rik van Riel
2010-05-03 17:17 ` Linus Torvalds
2010-05-03 17:17 ` Linus Torvalds
2010-05-03 17:58 ` Rik van Riel
2010-05-03 17:58 ` Rik van Riel
2010-05-03 18:13 ` Andrea Arcangeli
2010-05-03 18:13 ` Andrea Arcangeli
2010-05-03 18:19 ` Linus Torvalds
2010-05-03 18:19 ` Linus Torvalds
2010-05-03 18:38 ` Rik van Riel
2010-05-03 18:38 ` Rik van Riel
2010-05-04 13:12 ` Mel Gorman
2010-05-04 13:12 ` Mel Gorman
2010-05-03 16:55 ` Peter Zijlstra
2010-05-03 16:55 ` Peter Zijlstra
2010-05-03 17:02 ` Andrea Arcangeli
2010-05-03 17:02 ` Andrea Arcangeli
2010-05-03 17:11 ` Peter Zijlstra
2010-05-03 17:11 ` Peter Zijlstra
2010-05-03 17:18 ` Andrea Arcangeli
2010-05-03 17:18 ` Andrea Arcangeli
2010-05-03 16:19 ` [PATCH 2/2] mm: fix race between shift_arg_pages and rmap_walk Rik van Riel
2010-05-03 16:19 ` Rik van Riel
2010-05-03 16:34 ` Linus Torvalds
2010-05-03 16:34 ` Linus Torvalds
2010-05-03 16:37 ` Linus Torvalds
2010-05-03 16:37 ` Linus Torvalds
-- strict thread matches above, loose matches on Subject: below --
2010-04-29 8:32 [PATCH 0/2] Fix migration races in rmap_walk() V3 Mel Gorman
2010-04-29 8:32 ` [PATCH 1/2] mm: Take all anon_vma locks in anon_vma_lock Mel Gorman
2010-04-29 8:32 ` Mel Gorman
2010-05-02 17:28 ` Minchan Kim
2010-05-02 17:28 ` Minchan Kim
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