linux-kernel - Re: [PATCH 0/6] mempolicy memory corruption fixlet

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Message-ID: <20120530195244.GX27374@one.firstfloor.org>
Date:	Wed, 30 May 2012 21:52:44 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Christoph Lameter <cl@...ux.com>
Cc:	Andi Kleen <andi@...stfloor.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	kosaki.motohiro@...il.com, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, Andrew Morton <akpm@...gle.com>,
	Dave Jones <davej@...hat.com>, Mel Gorman <mgorman@...e.de>,
	stable@...r.kernel.org, hughd@...gle.com, sivanich@....com,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Subject: Re: [PATCH 0/6] mempolicy memory corruption fixlet

On Wed, May 30, 2012 at 02:42:42PM -0500, Christoph Lameter wrote:
> On Wed, 30 May 2012, Andi Kleen wrote:
> 
> > On Wed, May 30, 2012 at 01:50:02PM -0500, Christoph Lameter wrote:
> > > On Wed, 30 May 2012, Andi Kleen wrote:
> > >
> > > > I always regretted that cpusets were no done with custom node lists.
> > > > That would have been much cleaner and also likely faster than what we have.
> > >
> > > Could shared memory policies ignore cpuset constraints?
> >
> > Only if noone uses cpusets as a "security" mechanism, just for a "soft policy"
> > Even with soft policy you could well break someone's setup.
> 
> Well at least lets exempt shared memory from memory migration and memory
> policy updates. That seems to be causing many of these issues.

Migration on the page level is needed for the memory error handling.

Updates: you mean not allowing to set the policy when there are already
multiple mappers? I could see that causing some unexpected behaviour. Presumably
a standard database will only set it at the beginning, but I don't know
if that would work for all users.

-Andi
-- 
ak@...ux.intel.com -- Speaking for myself only.
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