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Date: Fri, 29 May 2009 12:34:32 -0400
From: Rik van Riel <riel@redhat.com>
Organization: Red Hat, Inc
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To: Andi Kleen <andi@firstfloor.org>
CC: Alan Cox <alan@lxorguk.ukuu.org.uk>, akpm@linux-foundation.org,
       linux-kernel@vger.kernel.org, linux-mm@kvack.org,
       fengguang.wu@intel.com
Subject: Re: [PATCH] [1/16] HWPOISON: Add page flag for poisoned pages
References: <200905271012.668777061@firstfloor.org> <20090527201226.CCCBB1D028F@basil.firstfloor.org> <20090527221510.5e418e97@lxorguk.ukuu.org.uk> <20090528075416.GY1065@one.firstfloor.org> <4A2008F0.1070304@redhat.com> <20090529163757.GX1065@one.firstfloor.org>
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Andi Kleen wrote:
> On Fri, May 29, 2009 at 12:10:24PM -0400, Rik van Riel wrote:
>> Andi Kleen wrote:
>>> On Wed, May 27, 2009 at 10:15:10PM +0100, Alan Cox wrote:
>>>> On Wed, 27 May 2009 22:12:26 +0200 (CEST)
>>>> Andi Kleen <andi@firstfloor.org> wrote:
>>>>
>>>>> Hardware poisoned pages need special handling in the VM and shouldn't be 
>>>>> touched again. This requires a new page flag. Define it here.
>>>> Why can't you use PG_reserved ? That already indicates the page may not
>>>> even be present (which is effectively your situation at that point).
>>> Right now a page must be present with PG_reserved, otherwise /dev/mem, 
>>> /proc/kcore
>>> lots of other things will explode.
>> Could we use a combination of, say PG_reserved and
>> PG_writeback to keep /dev/mem and /proc/kcore from
>> exploding ?
> 
> They should just check for poisoned pages. 

#define PagePoisoned(page) (PageReserved(page) && PageWriteback(page))

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