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To: Joe Korty <joe.korty@ccur.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: mlockall and mmap of IO devices don't mix
From: Andi Kleen <ak@muc.de>
Date: Sat, 04 Oct 2003 09:02:59 +0200
In-Reply-To: <CFYv.787.23@gated-at.bofh.it> (Joe Korty's message of "Fri, 03
 Oct 2003 23:50:19 +0200")
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Joe Korty <joe.korty@ccur.com> writes:

>  
> I do not believe that the above constitutes a correct fix.  The
> problem is that follow_pages() is fundamentally not able to handle a
> mapping which does not have a 'struct page' backing it up, and a
> mapping to IO memory by definition has no 'struct page' structure to
> back it up.

The 2.4 vm scanner handles this by always checking VALID_PAGE().

Maybe follow_pages() should do that too?

-Andi