From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262474AbTEEQFQ (ORCPT ); Mon, 5 May 2003 12:05:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262490AbTEEQFQ (ORCPT ); Mon, 5 May 2003 12:05:16 -0400 Received: from mailrelay2.lanl.gov ([128.165.4.103]:55784 "EHLO mailrelay2.lanl.gov") by vger.kernel.org with ESMTP id S262474AbTEEQFP (ORCPT ); Mon, 5 May 2003 12:05:15 -0400 Subject: Re: Linux 2.5.69 From: Steven Cole To: Linus Torvalds Cc: David van Hoose , Kernel Mailing List In-Reply-To: References: Content-Type: text/plain Organization: Message-Id: <1052151367.2163.100.camel@spc9.esa.lanl.gov> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.2.4-1.1mdk Date: 05 May 2003 10:16:07 -0600 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2003-05-05 at 09:56, Linus Torvalds wrote: > [ Linux-kernel added to the cc, since I got several queries about what the > crashes were.. ] > > On Mon, 5 May 2003, David van Hoose wrote: > > > > Can I get some details regarding the AGP problem? I had some really bad > > random crashes, panics, and hardlocks up through 2.5.68, and I'm > > wondering if this is the same issue. I first noticed them around 2.5.63. > > They actually started in 2.5.60 if it's the same bug. > > And yes, you'd get random crashes, panics, lockups and even reboots. The > problem was that the pmd/pgd's were put in the slab cache in between > 2.5.59 and 2.5.60, and that was simply wrong because the AGP code changes > the cacheability of the kernel pages when it maps stuff into the AGP > aperture. That in turn will change the page tables but it won't update the > cached entries in the pmd slab caches. > > So what happens is that once you exit X, and the page tables are put back > together without the cacheability changes, and you start a new program, > that program may get a page table with partly bogus kernel page table > entries. > > That, in turn, when it happens will cause _major_ memory corruption, and > your machine is toast, often in very interesting ways because the internal > kernel data structures got corrupted. It can also cause random SIGSEGV's > etc. > > But it only happens with AGP, and a lot of people either don't use it or > run only one X session. > > Linus This fixes a problem I reported here: http://marc.theaimsgroup.com/?l=linux-kernel&m=104990441203933&w=2 Thanks, Steven