From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with ESMTP id 8763860021B for ; Sun, 27 Dec 2009 19:57:56 -0500 (EST) Received: from d23relay05.au.ibm.com (d23relay05.au.ibm.com [202.81.31.247]) by e23smtp06.au.ibm.com (8.14.3/8.13.1) with ESMTP id nBS0vnCT028680 for ; Mon, 28 Dec 2009 11:57:49 +1100 Received: from d23av03.au.ibm.com (d23av03.au.ibm.com [9.190.234.97]) by d23relay05.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id nBS0rdom1462424 for ; Mon, 28 Dec 2009 11:53:39 +1100 Received: from d23av03.au.ibm.com (loopback [127.0.0.1]) by d23av03.au.ibm.com (8.14.3/8.13.1/NCO v10.0 AVout) with ESMTP id nBS0vpTi014205 for ; Mon, 28 Dec 2009 11:57:51 +1100 Date: Mon, 28 Dec 2009 06:27:46 +0530 From: Balbir Singh Subject: Re: [RFC PATCH] asynchronous page fault. Message-ID: <20091228005746.GE3601@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <20091225105140.263180e8.kamezawa.hiroyu@jp.fujitsu.com> <1261912796.15854.25.camel@laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <1261912796.15854.25.camel@laptop> Sender: owner-linux-mm@kvack.org To: Peter Zijlstra Cc: KAMEZAWA Hiroyuki , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "minchan.kim@gmail.com" , cl@linux-foundation.org List-ID: * Peter Zijlstra [2009-12-27 12:19:56]: > Your changelog states as much. > > "Even if RB-tree rotation occurs while we walk tree for look-up, we just > miss vma without oops." > > However, since this is the case, do we still need the > rcu_assign_pointer() conversion your patch does? All I can see it do is > slow down all RB-tree users, without any gain. Don't we need the rcu_assign_pointer() on the read side primarily to make sure the pointer is still valid and assignments (writes) are not re-ordered? Are you suggesting that the pointer assignment paths be completely atomic? -- Balbir -- 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