From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753629Ab0CYJMg (ORCPT ); Thu, 25 Mar 2010 05:12:36 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:35116 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751161Ab0CYJMf (ORCPT ); Thu, 25 Mar 2010 05:12:35 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Thu, 25 Mar 2010 18:08:46 +0900 From: KAMEZAWA Hiroyuki To: KOSAKI Motohiro Cc: Mel Gorman , Minchan Kim , Andrew Morton , Andrea Arcangeli , Christoph Lameter , Adam Litke , Avi Kivity , David Rientjes , Rik van Riel , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 02/11] mm,migration: Do not try to migrate unmapped anonymous pages Message-Id: <20100325180846.c6ded3ab.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20100325180726.6C89.A69D9226@jp.fujitsu.com> References: <20100325083235.GF2024@csn.ul.ie> <20100325180221.e1d9bae7.kamezawa.hiroyu@jp.fujitsu.com> <20100325180726.6C89.A69D9226@jp.fujitsu.com> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 3.0.1 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 25 Mar 2010 18:09:34 +0900 (JST) KOSAKI Motohiro wrote: > > On Thu, 25 Mar 2010 08:32:35 +0000 > > Mel Gorman wrote: > > IIUC, the race in memory-hotunplug was fixed by this patch [2/11]. > > > > But, this behavior of unmap_and_move() requires access to _freed_ > > objects (spinlock). Even if it's safe because of SLAB_DESTROY_BY_RCU, > > it't not good habit in general. > > > > After direct compaction, page-migration will be one of "core" code of > > memory management. Then, I agree to patch [1/11] as our direction for > > keeping sanity and showing direction to more updates. Maybe adding > > refcnt and removing RCU in futuer is good. > > But Christoph seems oppose to remove SLAB_DESTROY_BY_RCU. then refcount > is meaningless now. I agree you if we will remove SLAB_DESTROY_BY_RCU > in the future. > removing rcu_read_lock/unlock in unmap_and_move() and removing SLAB_DESTROY_BY_RCU is different story. Thanks, -Kame From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id 62DB16B0071 for ; Thu, 25 Mar 2010 05:12:34 -0400 (EDT) Received: from m4.gw.fujitsu.co.jp ([10.0.50.74]) by fgwmail5.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o2P9CViM026983 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Thu, 25 Mar 2010 18:12:32 +0900 Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id BC4BE45DE7C for ; Thu, 25 Mar 2010 18:12:31 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (s4.gw.fujitsu.co.jp [10.0.50.94]) by m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 9290145DE70 for ; Thu, 25 Mar 2010 18:12:31 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 7C10BE18008 for ; Thu, 25 Mar 2010 18:12:31 +0900 (JST) Received: from m108.s.css.fujitsu.com (m108.s.css.fujitsu.com [10.249.87.108]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 26E15E18003 for ; Thu, 25 Mar 2010 18:12:31 +0900 (JST) Date: Thu, 25 Mar 2010 18:08:46 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH 02/11] mm,migration: Do not try to migrate unmapped anonymous pages Message-Id: <20100325180846.c6ded3ab.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20100325180726.6C89.A69D9226@jp.fujitsu.com> References: <20100325083235.GF2024@csn.ul.ie> <20100325180221.e1d9bae7.kamezawa.hiroyu@jp.fujitsu.com> <20100325180726.6C89.A69D9226@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: KOSAKI Motohiro Cc: Mel Gorman , Minchan Kim , Andrew Morton , Andrea Arcangeli , Christoph Lameter , Adam Litke , Avi Kivity , David Rientjes , Rik van Riel , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Thu, 25 Mar 2010 18:09:34 +0900 (JST) KOSAKI Motohiro wrote: > > On Thu, 25 Mar 2010 08:32:35 +0000 > > Mel Gorman wrote: > > IIUC, the race in memory-hotunplug was fixed by this patch [2/11]. > > > > But, this behavior of unmap_and_move() requires access to _freed_ > > objects (spinlock). Even if it's safe because of SLAB_DESTROY_BY_RCU, > > it't not good habit in general. > > > > After direct compaction, page-migration will be one of "core" code of > > memory management. Then, I agree to patch [1/11] as our direction for > > keeping sanity and showing direction to more updates. Maybe adding > > refcnt and removing RCU in futuer is good. > > But Christoph seems oppose to remove SLAB_DESTROY_BY_RCU. then refcount > is meaningless now. I agree you if we will remove SLAB_DESTROY_BY_RCU > in the future. > removing rcu_read_lock/unlock in unmap_and_move() and removing SLAB_DESTROY_BY_RCU is different story. 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