From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with SMTP id D77DE6B01F1 for ; Mon, 26 Apr 2010 05:53:06 -0400 (EDT) Received: from m1.gw.fujitsu.co.jp ([10.0.50.71]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o3Q9r4Dj028577 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Mon, 26 Apr 2010 18:53:05 +0900 Received: from smail (m1 [127.0.0.1]) by outgoing.m1.gw.fujitsu.co.jp (Postfix) with ESMTP id 445DD45DE54 for ; Mon, 26 Apr 2010 18:53:04 +0900 (JST) Received: from s1.gw.fujitsu.co.jp (s1.gw.fujitsu.co.jp [10.0.50.91]) by m1.gw.fujitsu.co.jp (Postfix) with ESMTP id 0AFBC45DE51 for ; Mon, 26 Apr 2010 18:53:04 +0900 (JST) Received: from s1.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s1.gw.fujitsu.co.jp (Postfix) with ESMTP id E41091DB8058 for ; Mon, 26 Apr 2010 18:53:03 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.249.87.105]) by s1.gw.fujitsu.co.jp (Postfix) with ESMTP id 8A9FA1DB8055 for ; Mon, 26 Apr 2010 18:53:03 +0900 (JST) Date: Mon, 26 Apr 2010 18:49:08 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [BUGFIX][mm][PATCH] fix migration race in rmap_walk Message-Id: <20100426184908.3c277568.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: References: <20100423120148.9ffa5881.kamezawa.hiroyu@jp.fujitsu.com> <20100423095922.GJ30306@csn.ul.ie> <20100423155801.GA14351@csn.ul.ie> <20100424110200.b491ec5f.kamezawa.hiroyu@jp.fujitsu.com> <20100424104324.GD14351@csn.ul.ie> <20100426084901.15c09a29.kamezawa.hiroyu@jp.fujitsu.com> <20100426182838.2cab9844.kamezawa.hiroyu@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org To: Minchan Kim Cc: Mel Gorman , "linux-mm@kvack.org" , Christoph Lameter , "akpm@linux-foundation.org" , "linux-kernel@vger.kernel.org" List-ID: On Mon, 26 Apr 2010 18:48:42 +0900 Minchan Kim wrote: > On Mon, Apr 26, 2010 at 6:28 PM, KAMEZAWA Hiroyuki > wrote: > > On Mon, 26 Apr 2010 08:49:01 +0900 > > KAMEZAWA Hiroyuki wrote: > > > >> On Sat, 24 Apr 2010 11:43:24 +0100 > >> Mel Gorman wrote: > > > >> > It looks nice but it still broke after 28 hours of running. The > >> > seq-counter is still insufficient to catch all changes that are made to > >> > the list. I'm beginning to wonder if a) this really can be fully safely > >> > locked with the anon_vma changes and b) if it has to be a spinlock to > >> > catch the majority of cases but still a lazy cleanup if there happens to > >> > be a race. It's unsatisfactory and I'm expecting I'll either have some > >> > insight to the new anon_vma changes that allow it to be locked or Rik > >> > knows how to restore the original behaviour which as Andrea pointed out > >> > was safe. > >> > > >> Ouch. > > > > Ok, reproduced. Here is status in my test + printk(). > > > > A * A race doesn't seem to happen if swap=off. > > A A I need to swapon to cause the bug > > FYI, > > Do you have a swapon/off bomb test? No. Just running test under swapoff, and running the same test after swapon. > When I saw your mail, I feel it might be culprit. > > http://lkml.org/lkml/2010/4/22/762. > > It is just guessing. I don't have a time to look into, now. > Hmm. BTW. == static int expand_downwards(struct vm_area_struct *vma, unsigned long address) { .... /* Somebody else might have raced and expanded it already */ if (address < vma->vm_start) { unsigned long size, grow; size = vma->vm_end - address; grow = (vma->vm_start - address) >> PAGE_SHIFT; error = acct_stack_growth(vma, size, grow); if (!error) { vma->vm_start = address; vma->vm_pgoff -= grow; } } == I feel this part needs care. No ? Thanks, -Kmae -- 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