Subject: Re: [patch 3/9] Guest page hinting: volatile page cache.
From: Dave Hansen <haveblue@us.ibm.com>
To: schwidefsky@de.ibm.com
Cc: Andy Whitcroft <apw@shadowen.org>, linux-kernel@vger.kernel.org,
       virtualization@lists.osdl.org, akpm@osdl.org, nickpiggin@yahoo.com.au,
       frankeh@watson.ibm.com
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Date: Fri, 01 Sep 2006 11:03:00 -0700
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On Fri, 2006-09-01 at 19:42 +0200, Martin Schwidefsky wrote: 
> The problem of page discard vs. normal page remove is that the page can
> be remove and discarded at the same time. Both sides are writers in the
> sense that they want to remove the page from page cache. RCU doesn't not
> help with that kind of race. 

OK.  It comes down to a race between 

	__remove_from_page_cache()/__delete_from_swap_cache()

and

	__page_discard()

running on the same page at the same time.  Right?

-- Dave

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