linux-kernel - Re: 2.6.19 file content corruption on ext3

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Message-ID: <4587C5C8.2060304@yahoo.com.au>
Date:	Tue, 19 Dec 2006 21:58:16 +1100
From:	Nick Piggin <nickpiggin@...oo.com.au>
To:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
CC:	Andrew Morton <akpm@...l.org>, Linus Torvalds <torvalds@...l.org>,
	andrei.popa@...eo.ro,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Hugh Dickins <hugh@...itas.com>,
	Florian Weimer <fw@...eb.enyo.de>,
	Marc Haber <mh+linux-kernel@...schlus.de>,
	Martin Michlmayr <tbm@...ius.com>
Subject: Re: 2.6.19 file content corruption on ext3

Peter Zijlstra wrote:
> On Tue, 2006-12-19 at 02:32 -0800, Andrew Morton wrote:

>>Well it used to be.  After 2.6.19 it can do the wrong thing for mapped
>>pages.  But it turns out that we don't feed it mapped pages, apart from
>>pagevec_strip() and possibly races against pagefaults.
> 
> 
> So how about this:

Well that's still racy. Anyway several earlier patches (including
the one I posted) closed this race. Some were still reported to
trigger corruption IIRC.

> Index: linux-2.6-git/mm/page-writeback.c
> ===================================================================
> --- linux-2.6-git.orig/mm/page-writeback.c	2006-12-19 08:24:48.000000000 +0100
> +++ linux-2.6-git/mm/page-writeback.c	2006-12-19 11:43:31.000000000 +0100
> @@ -859,6 +859,9 @@ int test_clear_page_dirty(struct page *p
>  	struct address_space *mapping = page_mapping(page);
>  	unsigned long flags;
>  
> +	if (page_mapped(page))
> +		return 0;
> +
>  	if (!mapping)
>  		return TestClearPageDirty(page);
>  
> 
> 
> -

-- 
SUSE Labs, Novell Inc.
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