From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758014AbZBTCBx (ORCPT ); Thu, 19 Feb 2009 21:01:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752483AbZBTCBp (ORCPT ); Thu, 19 Feb 2009 21:01:45 -0500 Received: from smtp1.linux-foundation.org ([140.211.169.13]:56949 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751340AbZBTCBo (ORCPT ); Thu, 19 Feb 2009 21:01:44 -0500 Date: Thu, 19 Feb 2009 18:00:48 -0800 (PST) From: Linus Torvalds X-X-Sender: torvalds@localhost.localdomain To: Steven Rostedt cc: linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , Thomas Gleixner , Peter Zijlstra , Frederic Weisbecker , Arjan van de Ven , Rusty Russell , Mathieu Desnoyers , "H. Peter Anvin" Subject: Re: [git pull] changes for tip, and a nasty x86 page table bug In-Reply-To: <20090220011316.379904625@goodmis.org> Message-ID: References: <20090220011316.379904625@goodmis.org> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 19 Feb 2009, Steven Rostedt wrote: > > In doing this change, I stumbled upon a nasty bug in the page handling > of the x86 code, where we can fall into a state where the PTE > has the RW bit set, but the PMD does not. How do we ever have a PMD that is read-only? That sounds like a bug to begin with. There's no reason to ever do that. In fact, it should trigger the pmd_bad() tests if it ever happens, wouldn't it? We want all the _KERNPG_TABLE bits to always be set, no? Linus