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Date: Wed, 24 Mar 2010 22:57:29 +0100
From: Andrea Arcangeli <aarcange@redhat.com>
To: Jonathan Corbet <corbet@lwn.net>
Cc: Andrew Morton <akpm@linux-foundation.org>, Mel Gorman <mel@csn.ul.ie>,
       Christoph Lameter <cl@linux-foundation.org>,
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       KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
       KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
       Rik van Riel <riel@redhat.com>, linux-kernel@vger.kernel.org,
       linux-mm@kvack.org
Subject: Re: [PATCH 07/11] Memory compaction core
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On Wed, Mar 24, 2010 at 10:47:42PM +0100, Andrea Arcangeli wrote:
> As far as I can tell, VM_BUG_ON would make _zero_ differences there.
> 
> I think you mistaken a VM_BUG_ON for a:
> 
>   if (could_be_null->something) {

Ooops, I wrote ->something to indicate that "could_be_null" was going
to later be dereferenced for ->something and here we're checking if it
could be null when we dereference something, but now I think it could
be very confusing as I use strict C for all the rest, so maybe I
should clarify in C it would be !could_be_null.

>      WARN_ON(1);
>      return -ESOMETHING;
>   }
> 
> adding a VM_BUG_ON(inode->something) would _still_ be as exploitable

here the same !inode.