From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754539AbXJBWU1 (ORCPT ); Tue, 2 Oct 2007 18:20:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752082AbXJBWUS (ORCPT ); Tue, 2 Oct 2007 18:20:18 -0400 Received: from waste.org ([66.93.16.53]:33024 "EHLO waste.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750843AbXJBWUR (ORCPT ); Tue, 2 Oct 2007 18:20:17 -0400 Date: Tue, 2 Oct 2007 17:20:03 -0500 From: Matt Mackall To: Nick Piggin , Hugh Dickins Cc: linux-kernel Subject: pgd_none_or_clear_bad strangeness? Message-ID: <20071002222003.GL19691@waste.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org In lib/pagewalk.c, I've been using the various forms of {pgd,pud,pmd}_none_or_clear_bad while walking page tables as that seemed the canonical way to do things. Lately (eg with -rc7-mm1), these have been triggering messages like "bad pgd 0x01e3" and causing nasty double faults. It appears this is actually triggered at the pmd level (mm/memory.c:116), though it appears to produce the wrong message. Has something changed here? I'm pretty sure this used to work! Is this not a kosher thing to do? Does it make any sense I'd repeatedly run into a bad pmd in the middle of bash's page table right after boot? The simple _none variant seems to work, but I worry that it's papering over a real problem. -- Mathematics is the supreme nostalgia of our time.