Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752080AbZL1J6r (ORCPT ); Mon, 28 Dec 2009 04:58:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751894AbZL1J6q (ORCPT ); Mon, 28 Dec 2009 04:58:46 -0500 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:40267 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751810AbZL1J6q (ORCPT ); Mon, 28 Dec 2009 04:58:46 -0500 Message-ID: <27db4d47e5a95e7a85942c0278892467.squirrel@webmail-b.css.fujitsu.com> In-Reply-To: <1261989047.7135.3.camel@laptop> References: <20091225105140.263180e8.kamezawa.hiroyu@jp.fujitsu.com> <1261915391.15854.31.camel@laptop> <20091228093606.9f2e666c.kamezawa.hiroyu@jp.fujitsu.com> <1261989047.7135.3.camel@laptop> Date: Mon, 28 Dec 2009 18:58:43 +0900 (JST) Subject: Re: [RFC PATCH] asynchronous page fault. From: "KAMEZAWA Hiroyuki" To: "Peter Zijlstra" Cc: "KAMEZAWA Hiroyuki" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "minchan.kim@gmail.com" , cl@linux-foundation.org User-Agent: SquirrelMail/1.4.16 MIME-Version: 1.0 Content-Type: text/plain;charset=iso-2022-jp Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) Importance: Normal Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1028 Lines: 29 Peter Zijlstra さんは書きました： > On Mon, 2009-12-28 at 09:36 +0900, KAMEZAWA Hiroyuki wrote: >> >> > The idea is to let the RCU lock span whatever length you need the vma >> > for, the easy way is to simply use PREEMPT_RCU=y for now, >> >> I tried to remove his kind of reference count trick but I can't do that >> without synchronize_rcu() somewhere in unmap code. I don't like that and >> use this refcnt. > > Why, because otherwise we can access page tables for an already unmapped > vma? Yeah that is the interesting bit ;-) > Without that vma->a_ops->fault() and vma->a_ops->unmap() can be called at the same time. and vma->vm_file can be dropped while vma->a_ops->fault() is called. etc... Ah, I may miss something. I'll consider in the next year. Thanks, -Kame -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/