Date: Wed, 14 May 2003 13:05:56 -0500
From: Dave McCracken <dmccr@us.ibm.com>
To: Andrew Morton <akpm@digeo.com>
cc: mika.penttila@kolumbus.fi, linux-mm@kvack.org,
       linux-kernel@vger.kernel.org
Subject: Re: Race between vmtruncate and mapped areas?
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--On Wednesday, May 14, 2003 10:57:06 -0700 Andrew Morton <akpm@digeo.com>
wrote:

> yes.  It's a very complex way of allocating anonymous memory.

Yep.  And randomly, at that.

> I am told that Stephen, Linus and others discussed this at length at KS a
> couple of years ago and the upshot was that the application is racy anyway
> and there's nothing wrong with it.
> 
> Hugh calls these "Morton pages" but it wasn't me and nobody saw me do it.
> 
> It would be nice to make them go away - they cause problems.

Definitely.  We almost have the pieces necessary to detect it and/or
prevent it, but the info isn't in quite the right layer at the right time.
If it weren't for the lock order problem with mmap_sem we could have nailed
it that way.  Sigh.

Dave

======================================================================
Dave McCracken          IBM Linux Base Kernel Team      1-512-838-3059
dmccr@us.ibm.com                                        T/L   678-3059

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