From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755425AbYANQ5B (ORCPT ); Mon, 14 Jan 2008 11:57:01 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754094AbYANQ4s (ORCPT ); Mon, 14 Jan 2008 11:56:48 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:53865 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753978AbYANQ4r (ORCPT ); Mon, 14 Jan 2008 11:56:47 -0500 Date: Mon, 14 Jan 2008 17:56:35 +0100 From: Ingo Molnar To: Jeremy Fitzhardinge Cc: Andi Kleen , tglx@linutronix.de, linux-kernel@vger.kernel.org Subject: Re: unify pagetable accessors patch causes double fault II Message-ID: <20080114165635.GK15542@elte.hu> References: <20080114094814.GA28300@basil.nowhere.org> <20080114125638.GA9510@basil.nowhere.org> <20080114130620.GA14057@elte.hu> <20080114135811.GA16190@one.firstfloor.org> <478B9183.3020101@goop.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <478B9183.3020101@goop.org> User-Agent: Mutt/1.5.17 (2007-11-01) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Jeremy Fitzhardinge wrote: >> This is with PAE and seems to only happen with enough RAM (6GB); a >> 2GB system boots. 64bit also works. > > Thanks, I'll have a close look at it. Presumably a pfn is getting > truncated to 20/32-bits somewhere. would be nice to have some debugging apparatus for bugs like this. Perhaps artificially add a large pfn, then convert/unconvert, then subtract it and expect the whole transformation to be an identity mapping? This way we could simulate most of the effects of >4GB RAM, right? Ingo