From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with ESMTP id 554646B007B for ; Fri, 19 Feb 2010 08:59:52 -0500 (EST) Date: Fri, 19 Feb 2010 13:59:35 +0000 From: Mel Gorman Subject: Re: [PATCH 01/12] mm,migration: Take a reference to the anon_vma before migrating Message-ID: <20100219135934.GF30258@csn.ul.ie> References: <1266516162-14154-1-git-send-email-mel@csn.ul.ie> <1266516162-14154-2-git-send-email-mel@csn.ul.ie> <20100219091244.2116db73.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20100219091244.2116db73.kamezawa.hiroyu@jp.fujitsu.com> Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: Andrea Arcangeli , Christoph Lameter , Adam Litke , Avi Kivity , David Rientjes , KOSAKI Motohiro , Rik van Riel , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Fri, Feb 19, 2010 at 09:12:44AM +0900, KAMEZAWA Hiroyuki wrote: > On Thu, 18 Feb 2010 18:02:31 +0000 > Mel Gorman wrote: > > > rmap_walk_anon() does not use page_lock_anon_vma() for looking up and > > locking an anon_vma and it does not appear to have sufficient locking to > > ensure the anon_vma does not disappear from under it. > > > > This patch copies an approach used by KSM to take a reference on the > > anon_vma while pages are being migrated. This should prevent rmap_walk() > > running into nasty surprises later because anon_vma has been freed. > > > > Signed-off-by: Mel Gorman > > I have no objection to this direction. But after this patch, you can remove > rcu_read_lock()/unlock() in unmap_and_move(). > ruc_read_lock() is for guarding against anon_vma replacement. > Thanks. I expected that would be the case but was going to leave at least one kernel release between when compaction went in and I did that. -- 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