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

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Message-ID: <alpine.DEB.2.02.1206011230170.17976@asgard.lang.hm>
Date:	Fri, 1 Jun 2012 12:31:33 -0700 (PDT)
From:	david@...g.hm
To:	Christoph Lameter <cl@...ux.com>
cc:	KOSAKI Motohiro <kosaki.motohiro@...il.com>,
	Andi Kleen <andi@...stfloor.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	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
Subject: Re: [PATCH 0/6] mempolicy memory corruption fixlet

On Fri, 1 Jun 2012, Christoph Lameter wrote:

> Subject: Re: [PATCH 0/6] mempolicy memory corruption fixlet
> 
> On Thu, 31 May 2012, david@...g.hm wrote:
>
>> On Wed, 30 May 2012, KOSAKI Motohiro wrote:
>>
>>> On Wed, May 30, 2012 at 4:10 PM, Andi Kleen <andi@...stfloor.org> wrote:
>>>>> Yes, that's right direction, I think. Currently, shmem_set_policy()
>>>>> can't handle
>>>>> nonlinear mapping.
>>>>
>>>> I've been mulling for some time to just remove non linear mappings.
>>>> AFAIK they were only useful on 32bit and are obsolete and could be
>>>> emulated with VMAs instead.
>>>
>>> I agree. It is only userful on 32bit and current enterprise users don't use
>>> 32bit anymore. So, I don't think emulated by vmas cause user visible issue.
>>
>> I wish this was true, there are a lot of systems out there still running 32
>> bit linux, even on 64 bit capible hardware. This is especially true in
>> enterprises where they have either homegrown or proprietary software that
>> isn't 64 bit clean.
>
> 32 bit binaries (and entire distros) run fine under 64 bit kernels.

unfortunantly, not quite 100% of the time. It's very good, but the 
automount bug a month or so ago is an example of how you can run into rare 
problems. Many "enterprise" systems are not willing to risk it.

David Lang
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