Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751655AbWAOF3G (ORCPT ); Sun, 15 Jan 2006 00:29:06 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751671AbWAOF3G (ORCPT ); Sun, 15 Jan 2006 00:29:06 -0500 Received: from smtp203.mail.sc5.yahoo.com ([216.136.129.93]:62347 "HELO smtp203.mail.sc5.yahoo.com") by vger.kernel.org with SMTP id S1751655AbWAOF3F (ORCPT ); Sun, 15 Jan 2006 00:29:05 -0500 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com.au; h=Received:Message-ID:Date:From:User-Agent:X-Accept-Language:MIME-Version:To:CC:Subject:References:In-Reply-To:Content-Type:Content-Transfer-Encoding; b=Q95eJQJEtKXvu5/5vt0X+zjFT6PL1XiC3ddBhafw6mh1vyGjrT+00LUF9PJhJHI+e1mSM5ZzicsIRLL+8knHb3YNGF7+ojX4juSeMjfO1yLBsT1RnajHpaEa/x5jD0eZTxHMLRlaGwlUxOr9XX+6Z8Xa7aGTo7s2rtjGB0Wywn0= ; Message-ID: <43C9DD98.5000506@yahoo.com.au> Date: Sun, 15 Jan 2006 16:28:56 +1100 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20051007 Debian/1.7.12-1 X-Accept-Language: en MIME-Version: 1.0 To: Christoph Lameter CC: Nick Piggin , Andrew Morton , Linux Kernel Mailing List , Linux Memory Management List Subject: Re: Race in new page migration code? References: <20060114155517.GA30543@wotan.suse.de> <20060114181949.GA27382@wotan.suse.de> In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1386 Lines: 41 Christoph Lameter wrote: > On Sat, 14 Jan 2006, Nick Piggin wrote: > > >>>We take that reference count on the page: >> >>Yes, after you have dropped all your claims to pin this page >>(ie. pte lock). You really can't take a refcount on a page that > > > Oh. Now I see. I screwed that up by a fix I added.... We cannot drop the > ptl here. So back to the way it was before. Remove the draining from > isolate_lru_page and do it before scanning for pages so that we do not > have to drop the ptl. > OK (either way is fine), but you should still drop the __isolate_lru_page nonsense and revert it like my patch does. > Also remove the WARN_ON since its now even possible that other actions of > the VM move the pages into the LRU lists while we scan for pages to > migrate. > Well, it has always been possible since vmscan started batching scans a long time ago. Actually seeing as you only take a read lock on the semaphore it is probably also possible to have a concurrent migrate operation cause this as well. Thanks, Nick -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/