Date: Tue, 10 Oct 2006 19:12:54 +0100 (BST)
From: Hugh Dickins <hugh@veritas.com>
To: Greg KH <gregkh@suse.de>
cc: linux-kernel@vger.kernel.org, stable@kernel.org, torvalds@osdl.org,
       Justin Forbes <jmforbes@linuxtx.org>,
       Zwane Mwaikambo <zwane@arm.linux.org.uk>,
       "Theodore Ts'o" <tytso@mit.edu>, Randy Dunlap <rdunlap@xenotime.net>,
       Dave Jones <davej@redhat.com>, Chuck Wolber <chuckw@quantumlinux.com>,
       Chris Wedgwood <reviews@ml.cw.f00f.org>,
       Michael Krufky <mkrufky@linuxtv.org>, akpm@osdl.org,
       alan@lxorguk.ukuu.org.uk, Nick Piggin <nickpiggin@yahoo.com.au>
Subject: Re: [patch 07/19] invalidate_complete_page() race fix
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On Tue, 10 Oct 2006, Greg KH wrote:

> -stable review patch.  If anyone has any objections, please let us know.
> 
> ------------------
> From: Andrew Morton <akpm@osdl.org>
> 
> If a CPU faults this page into pagetables after invalidate_mapping_pages()
> checked page_mapped(), invalidate_complete_page() will still proceed to remove
> the page from pagecache.  This leaves the page-faulting process with a
> detached page.  If it was MAP_SHARED then file data loss will ensue.
> 
> Fix that up by checking the page's refcount after taking tree_lock.

I may have lost the plot, but I think this patch has already proved
to cause problems for NFS in 2.6.18: not good to put it into 2.6.17
stable while it's awaiting refinement for 2.6.18 stable.

Hugh
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