From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757161AbYDROr3 (ORCPT ); Fri, 18 Apr 2008 10:47:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753568AbYDROrV (ORCPT ); Fri, 18 Apr 2008 10:47:21 -0400 Received: from po-out-1718.google.com ([72.14.252.159]:59991 "EHLO po-out-1718.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753471AbYDROrT (ORCPT ); Fri, 18 Apr 2008 10:47:19 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=eD1Yf8heJ5kWkN3W1u9XVJFhjmhjI6GYKkJtVTHvnlup9+pjRF6KNopOJly1xfsVGOkSRWltz6U1tztW0xJUjLKI8kE5no3EjsvnofFK0H/i5qlA9jBfblMzpCLsjb/65dZZZ/th1cS/iwQqJPs18+84eO0uwNeYFmqxgh0aFyk= Message-ID: <19f34abd0804180747i244c483flf8421f42a330c519@mail.gmail.com> Date: Fri, 18 Apr 2008 16:47:17 +0200 From: "Vegard Nossum" To: "Jason Wessel" Subject: Re: 2.6.25-mm1: not looking good Cc: "Ingo Molnar" , "Andrew Morton" , tglx@linutronix.de, penberg@cs.helsinki.fi, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, jmorris@namei.org, sds@tycho.nsa.gov In-Reply-To: <4808A1C7.7000907@windriver.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20080417160331.b4729f0c.akpm@linux-foundation.org> <20080417171413.6f8458e4.akpm@linux-foundation.org> <48080FE7.1070400@windriver.com> <20080418073732.GA22724@elte.hu> <19f34abd0804180446u2d6f17damf391a8c0584358b8@mail.gmail.com> <20080418123439.GA17013@elte.hu> <19f34abd0804180541l7b4d14a6tb13bdd51dd533d70@mail.gmail.com> <48089BCA.1090704@windriver.com> <19f34abd0804180622l4f89191cp4cc7833822e058f5@mail.gmail.com> <4808A1C7.7000907@windriver.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/18/08, Jason Wessel wrote: > Vegard Nossum wrote: > > On Fri, Apr 18, 2008 at 3:02 PM, Jason Wessel > > wrote: > > > >> Vegard Nossum wrote: > >> > On Fri, Apr 18, 2008 at 2:34 PM, Ingo Molnar wrote: > >> > > >> >> * Vegard Nossum wrote: > >> >> > >> >> > With the patch below, it seems 100% reproducible to me (7 out of 7 > >> >> > bootups hung). > >> >> > > >> >> > The number of loops it could do before hanging were, in order: > 697, > >> >> > 898, 237, 55, 45, 92, 59 > >> >> > >> >> cool! Jason: i think that particular self-test should be repeated > 1000 > >> >> times before reporting success ;-) > >> >> > >> > > >> > BTW, I just tested a 32-bit config and it hung after 55 iterations as > well. > >> > > >> > Vegard > >> > > >> > > >> > > >> I assume this was SMP? > >> > > > > Yes. But now that I realize this, I tried running same kernel with > > qemu, using -smp 16, and it seems to be stuck here: > > > > > > Unless you have a qemu with the NMI patches, kgdb does not work on SMP > with qemu. The very first test is going to fail because the IPI sent by > the kernel is not handled in qemu's hardware emulation. Oops, no, and that makes sense. I now picked up qemu 0.9.1 and applied the three NMI/SMI patches by Jan Kiszka. So in qemu it seems to run fine now, except that I need to prod it sometimes (it gets stuck in cpu_clock() and I have to break/continue from gdb to make it proceed). Oh, there it made it to 1056, and gdb can't interrupt anymore. Hmm. This is probably not a very good testing/debugging environment if the qemu support is that bad. Sorry :-) But booting with nosmp on real hardware gets easily above 100,000 iterations of the loop (before I reboot), so it seems to be related to that, anyway. Vegard -- "The animistic metaphor of the bug that maliciously sneaked in while the programmer was not looking is intellectually dishonest as it disguises that the error is the programmer's own creation." -- E. W. Dijkstra, EWD1036