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Date: Thu, 3 Apr 2003 12:06:11 -0800
From: Andrew Morton <akpm@digeo.com>
To: Dave McCracken <dmccr@us.ibm.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2.5.66-mm2] Fix page_convert_anon locking issues
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Dave McCracken <dmccr@us.ibm.com> wrote:
>
> 
> --On Wednesday, April 02, 2003 17:58:08 -0600 Dave McCracken
> <dmccr@us.ibm.com> wrote:
> 
> > It's looking more and more like we should use your other suggestion.  It's
> > definitely simpler if we can make it failsafe.  I'll code it up tomorrow.
> 
> I thought of a big hole in the simpler scheme you suggested.  It occurred
> to me that try_to_unmap will fail.  It will see the PageAnon flag so it'll
> just walk the pte_chain and assume it doesn't have to walk the vmas.  This
> will leave the page with some stranded mappings.  Actually
> page_convert_anon will then finish, and we'll have a page where
> try_to_unmap claims it has succeeded but still has mappings.
> 

page_referenced() has the same problem, so refill_inactive_zone() will need
to lock pages too.