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 SMTP id B1B316B01F6 for ; Tue, 27 Apr 2010 20:43:53 -0400 (EDT) Received: from m5.gw.fujitsu.co.jp ([10.0.50.75]) by fgwmail5.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o3S0hqb8000710 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Wed, 28 Apr 2010 09:43:52 +0900 Received: from smail (m5 [127.0.0.1]) by outgoing.m5.gw.fujitsu.co.jp (Postfix) with ESMTP id 72E4145DE52 for ; Wed, 28 Apr 2010 09:43:52 +0900 (JST) Received: from s5.gw.fujitsu.co.jp (s5.gw.fujitsu.co.jp [10.0.50.95]) by m5.gw.fujitsu.co.jp (Postfix) with ESMTP id 535DA45DE51 for ; Wed, 28 Apr 2010 09:43:52 +0900 (JST) Received: from s5.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s5.gw.fujitsu.co.jp (Postfix) with ESMTP id CF9FDE08002 for ; Wed, 28 Apr 2010 09:57:31 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.249.87.105]) by s5.gw.fujitsu.co.jp (Postfix) with ESMTP id CF9FD1DB8040 for ; Wed, 28 Apr 2010 09:57:31 +0900 (JST) Date: Wed, 28 Apr 2010 09:39:48 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH 3/3] mm,migration: Remove straggling migration PTEs when page tables are being moved after the VMA has already moved Message-Id: <20100428093948.c4e6faa1.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20100427225852.GH8860@random.random> References: <1272403852-10479-1-git-send-email-mel@csn.ul.ie> <1272403852-10479-4-git-send-email-mel@csn.ul.ie> <20100427223004.GF8860@random.random> <20100427225852.GH8860@random.random> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Andrea Arcangeli Cc: Mel Gorman , Linux-MM , LKML , Minchan Kim , Christoph Lameter , Rik van Riel , Andrew Morton List-ID: On Wed, 28 Apr 2010 00:58:52 +0200 Andrea Arcangeli wrote: > On Wed, Apr 28, 2010 at 12:30:04AM +0200, Andrea Arcangeli wrote: > > I'll now evaluate the fix and see if I can find any other > > way to handle this. > > > I think a better fix for bug mentioned in patch 3, is like below. This > seems to work fine on aa.git with the old (stable) 2.6.33 anon-vma > code. Not sure if this also works with the new anon-vma code in > mainline but at first glance I think it should. At that point we > should be single threaded so it shouldn't matter if anon_vma is > temporary null. > > Then you've to re-evaluate the vma_adjust fixes for mainline-only in > patch 2 at the light of the below (I didn't check patch 2 in detail). > > Please try to reproduce with the below applied. > > ---- > Subject: fix race between shift_arg_pages and rmap_walk > > From: Andrea Arcangeli > > migrate.c requires rmap to be able to find all ptes mapping a page at > all times, otherwise the migration entry can be instantiated, but it > can't be removed if the second rmap_walk fails to find the page. > > So shift_arg_pages must run atomically with respect of rmap_walk, and > it's enough to run it under the anon_vma lock to make it atomic. > > And split_huge_page() will have the same requirements as migrate.c > already has. > > Signed-off-by: Andrea Arcangeli Seems nice. I'll test this but I think we need to take care of do_mremap(), too. And it's more complicated.... Thanks, -Kame -- 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