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 034856B01F0 for ; Fri, 23 Apr 2010 00:55:21 -0400 (EDT) Received: by iwn40 with SMTP id 40so830564iwn.1 for ; Thu, 22 Apr 2010 21:55:20 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <1271797276-31358-1-git-send-email-mel@csn.ul.ie> <20100421153421.GM30306@csn.ul.ie> <20100422092819.GR30306@csn.ul.ie> <20100422184621.0aaaeb5f.kamezawa.hiroyu@jp.fujitsu.com> <20100422193106.9ffad4ec.kamezawa.hiroyu@jp.fujitsu.com> <20100422195153.d91c1c9e.kamezawa.hiroyu@jp.fujitsu.com> <1271946226.2100.211.camel@barrios-desktop> Date: Fri, 23 Apr 2010 13:55:19 +0900 Message-ID: Subject: Re: [PATCH 04/14] mm,migration: Allow the migration of PageSwapCache pages From: Minchan Kim Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org To: Christoph Lameter Cc: KAMEZAWA Hiroyuki , Mel Gorman , Andrew Morton , Andrea Arcangeli , Adam Litke , Avi Kivity , David Rientjes , KOSAKI Motohiro , Rik van Riel , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: Hi, Christoph. On Fri, Apr 23, 2010 at 12:14 AM, Christoph Lameter wrote: > On Thu, 22 Apr 2010, Minchan Kim wrote: > >> For further optimization, we can hold vma->adjust_lock if vma_address >> returns -EFAULT. But I hope we redesigns it without new locking. >> But I don't have good idea, now. :( > > You could make it atomic through the use of RCU. > > Create a new vma entry with the changed parameters and then atomically > switch to the new vma. > Problem is that you have some list_heads in there. That's a good idea if we can do _simply_. That's because there are many confusion anon_vma and vma handling nowadays. (http://thread.gmane.org/gmane.linux.kernel/969907) So I hope we solve the problem without rather complicated rcu locking if it isn't critical path. -- Kind regards, Minchan Kim -- 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