Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932205AbXJET5I (ORCPT ); Fri, 5 Oct 2007 15:57:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1762273AbXJET4y (ORCPT ); Fri, 5 Oct 2007 15:56:54 -0400 Received: from mx1.redhat.com ([66.187.233.31]:47058 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761872AbXJET4v (ORCPT ); Fri, 5 Oct 2007 15:56:51 -0400 Date: Fri, 5 Oct 2007 15:56:34 -0400 From: Rik van Riel To: Jeremy Fitzhardinge Cc: Hugh Dickins , David Rientjes , Zachary Amsden , Andrew Morton , Linus Torvalds , Rusty Russell , Andi Kleen , Keir Fraser , Linux Kernel Mailing List Subject: Re: race with page_referenced_one->ptep_test_and_clear_young and pagetable setup/pulldown Message-ID: <20071005155634.7d677970@cuia.boston.redhat.com> In-Reply-To: <47069315.8030802@goop.org> References: <470596C4.8060804@goop.org> <20071005145828.17ba9c69@cuia.boston.redhat.com> <47069315.8030802@goop.org> Organization: Red Hat, Inc X-Mailer: Claws Mail 3.0.0 (GTK+ 2.10.14; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 849 Lines: 21 On Fri, 05 Oct 2007 12:40:05 -0700 Jeremy Fitzhardinge wrote: > Well, isn't the correct fix to make Xen take all the pagetable locks > while pinning/unpinning? Adding exception handling to > test_and_clear_bit would solve this particular race, but are there > others (either now or potentially)? Seems fragile. You're right, holding the pagetable lock(s) across pinning/unpinning operations would avoid the problem too. While we do not care about the accessed bit, there are similar operations going on with the dirty bit - which is a lot more important :) -- All Rights Reversed - 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/