linux-kernel - Re: [PATCH 02/11] mm,migration: Do not try to migrate unmapped anonymous pages

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Message-ID: <20100326134930.GA2024@csn.ul.ie>
Date:	Fri, 26 Mar 2010 13:49:30 +0000
From:	Mel Gorman <mel@....ul.ie>
To:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Minchan Kim <minchan.kim@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Christoph Lameter <cl@...ux-foundation.org>,
	Adam Litke <agl@...ibm.com>, Avi Kivity <avi@...hat.com>,
	David Rientjes <rientjes@...gle.com>,
	Rik van Riel <riel@...hat.com>, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [PATCH 02/11] mm,migration: Do not try to migrate unmapped
	anonymous pages

On Fri, Mar 26, 2010 at 12:07:02PM +0900, KOSAKI Motohiro wrote:
> very small nit
> 
> > There were minor changes in how the rcu_read_lock is taken and released
> > based on other comments. With your suggestion, the block now looks like;
> > 
> >         if (PageAnon(page)) {
> >                 rcu_read_lock();
> >                 rcu_locked = 1;
> > 
> >                 /*
> >                  * If the page has no mappings any more, just bail. An
> >                  * unmapped anon page is likely to be freed soon but
> >                  * worse,
> >                  * it's possible its anon_vma disappeared between when
> >                  * the page was isolated and when we reached here while
> >                  * the RCU lock was not held
> >                  */
> >                 if (!page_mapcount(page) && !PageSwapCache(page))
> 
>                         page_mapped?
> 

Will be fixed in V6.

Thanks

> >                         goto rcu_unlock;
> > 
> >                 anon_vma = page_anon_vma(page);
> >                 atomic_inc(&anon_vma->external_refcount);
> >         }
> 
> 
> 

-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab
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