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Date: Mon, 3 Mar 2003 13:35:39 -0800
From: Andrew Morton <akpm@digeo.com>
To: Dave McCracken <dmccr@us.ibm.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 2.5.63] Teach page_mapped about the anon flag
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Dave McCracken <dmccr@us.ibm.com> wrote:
>
> 
> --On Monday, March 03, 2003 13:12:10 -0800 Andrew Morton <akpm@digeo.com>
> wrote:
> 
> > It is.  All callers which need to be 100% accurate are under
> > pte_chain_lock().
> 
> Hmm, good point.  Some places may not need perfect accuracy.  Also, if it
> gives a false positive it means someone else is doing an atomic op on it,
> so it's likely to be in transition to/from true anyway.
> 
> Ok, you've convinced me.  Please ignore the patch.  I'll hang onto it in
> case we get proved wrong at some point.

We do need a patch I think.  page_mapped() is still assuming that an
all-bits-zero atomic_t corresponds to a zero-value atomic_t.

This does appear to be true for all supported architectures, but it's a bit
grubby.

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