Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759488AbYFJVb1 (ORCPT ); Tue, 10 Jun 2008 17:31:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755270AbYFJVbS (ORCPT ); Tue, 10 Jun 2008 17:31:18 -0400 Received: from relay1.sgi.com ([192.48.171.29]:50763 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753659AbYFJVbQ (ORCPT ); Tue, 10 Jun 2008 17:31:16 -0400 Message-ID: <484EF29C.7080100@sgi.com> Date: Tue, 10 Jun 2008 14:31:08 -0700 From: Mike Travis User-Agent: Thunderbird 2.0.0.6 (X11/20070801) MIME-Version: 1.0 To: Ingo Molnar CC: Andrew Morton , Christoph Lameter , David Miller , Eric Dumazet , Jeremy Fitzhardinge , linux-kernel@vger.kernel.org, the arch/x86 maintainers Subject: Re: [crash, bisected] Re: [PATCH 3/4] x86_64: Fold pda into per cpu area References: <20080604003018.538497000@polaris-admin.engr.sgi.com> <20080604003019.509483000@polaris-admin.engr.sgi.com> <20080605102222.GA21319@elte.hu> In-Reply-To: <20080605102222.GA21319@elte.hu> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2806 Lines: 72 Ingo Molnar wrote: > * Mike Travis wrote: > >> * Declare the pda as a per cpu variable. >> >> * Make the x86_64 per cpu area start at zero. >> >> * Since the pda is now the first element of the per_cpu area, cpu_pda() >> is no longer needed and per_cpu() can be used instead. This also makes >> the _cpu_pda[] table obsolete. >> >> * Since %gs is pointing to the pda, it will then also point to the per cpu >> variables and can be accessed thusly: >> >> %gs:[&per_cpu_xxxx - __per_cpu_start] >> >> Based on linux-2.6.tip > > -tip testing found an instantaneous reboot crash on 64-bit x86, with > this config: > > http://redhat.com/~mingo/misc/config-Thu_Jun__5_11_43_51_CEST_2008.bad I'm still stuck on this one. One new development is that the current -tip branch without the patches boots to the kernel prompt then hangs after a few moments and then reboots. It seems you can tickle it using ^C to abort a process. -Mike > > there is no boot log as the instantaneous reboot happens before anything > is printed to the (early-) serial console. I have bisected it down to: > > | 7670dc09e89a2b151a1cf49eccebc07c41c2ce9f is first bad commit > | commit 7670dc09e89a2b151a1cf49eccebc07c41c2ce9f > | Author: Mike Travis > | Date: Tue Jun 3 17:30:21 2008 -0700 > | > | x86_64: Fold pda into per cpu area > > the big problem is not just this crash, but that the patch is _way_ too > big: > > arch/x86/Kconfig | 3 + > arch/x86/kernel/head64.c | 34 ++++++-------- > arch/x86/kernel/irq_64.c | 36 ++++++++------- > arch/x86/kernel/setup.c | 90 ++++++++++++--------------------------- > arch/x86/kernel/setup64.c | 5 -- > arch/x86/kernel/smpboot.c | 51 ---------------------- > arch/x86/kernel/traps_64.c | 11 +++- > arch/x86/kernel/vmlinux_64.lds.S | 1 > include/asm-x86/percpu.h | 48 ++++++-------------- > 9 files changed, 89 insertions(+), 190 deletions(-) > > considering the danger involved, this is just way too large, and there's > no reasonable debugging i can do in the bisection to narrow it down any > further. > > Please resubmit with the bug fixed and with a proper splitup, the more > patches you manage to create, the better. For a dangerous code area like > this, with a track record of frequent breakages in the past, i would not > mind a "one line of code changed per patch" splitup either. (Feel free > to send a git tree link for us to try as well.) > > Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/