From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with ESMTP id 37F436B01C4 for ; Tue, 23 Mar 2010 14:04:37 -0400 (EDT) Date: Tue, 23 Mar 2010 18:04:18 +0000 From: Mel Gorman Subject: Re: [PATCH 02/11] mm,migration: Do not try to migrate unmapped anonymous pages Message-ID: <20100323180418.GB5870@csn.ul.ie> References: <1269347146-7461-1-git-send-email-mel@csn.ul.ie> <1269347146-7461-3-git-send-email-mel@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org To: Christoph Lameter Cc: Andrew Morton , Andrea Arcangeli , Adam Litke , Avi Kivity , David Rientjes , Minchan Kim , KAMEZAWA Hiroyuki , KOSAKI Motohiro , Rik van Riel , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Tue, Mar 23, 2010 at 12:22:57PM -0500, Christoph Lameter wrote: > On Tue, 23 Mar 2010, Mel Gorman wrote: > > > diff --git a/mm/migrate.c b/mm/migrate.c > > index 98eaaf2..6eb1efe 100644 > > --- a/mm/migrate.c > > +++ b/mm/migrate.c > > @@ -603,6 +603,19 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private, > > */ > > if (PageAnon(page)) { > > rcu_read_lock(); > > + > > + /* > > + * 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)) { > > + rcu_read_unlock(); > > + goto uncharge; > > + } > > + > > rcu_locked = 1; > > anon_vma = page_anon_vma(page); > > atomic_inc(&anon_vma->migrate_refcount); > > A way to make this simpler would be to move "rcu_locked = 1" before the > if statement and then do > > if (!page_mapcount(page)) > goto rcu_unlock; > True. Fixed. -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org