From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757817AbYFSKdQ (ORCPT ); Thu, 19 Jun 2008 06:33:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755482AbYFSKdE (ORCPT ); Thu, 19 Jun 2008 06:33:04 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:57238 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755462AbYFSKdB (ORCPT ); Thu, 19 Jun 2008 06:33:01 -0400 Date: Thu, 19 Jun 2008 12:32:42 +0200 From: Ingo Molnar To: Jack Steiner Cc: tglx@linutronix.de, linux-kernel@vger.kernel.org, Mike Travis , the arch/x86 maintainers Subject: Re: [PATCH] - Increase MAX_APICS for very large x86_64 configs Message-ID: <20080619103242.GA13213@elte.hu> References: <20080616170910.GA24930@sgi.com> <20080619101030.GF15228@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080619101030.GF15228@elte.hu> User-Agent: Mutt/1.5.18 (2008-05-17) 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 * Ingo Molnar wrote: > > The patch has no effect on any 32-bit kernel. It adds ~4k to the > > size of 64-bit kernels but only if NR_CPUS > 255. > > > > This is a repost of an earlier patch (4/16) that was implicated in a > > random-qa failure. I have not been able to reproduce the failure > > using the same boot args & config. Best guess is that some other > > patch caused random data corruption & this patch was a victim. > > i have just re-tested the previously failing config on tip/master: > > http://redhat.com/~mingo/misc/config-Thu_Apr_17_10_17_14_CEST_2008.bad > http://people.redhat.com/mingo/tip.git/README > > and the good news is that it does not crash on bootup anymore. Perhaps > one of Mike's fixes/improvements did the trick? unfortunately it didnt last long, -tip randconfig auto-testing found that your patch causes a bootup crash: [ 0.352022] SMP mode deactivated. [ 0.355356] enabled ExtINT on CPU#0 [ 0.358861] SMP disabled [ 0.361829] BUG: unable to handle kernel NULL pointer dereference at 00000000000008b0 [ 0.364022] IP: [] debug_mutex_add_waiter+0x4e/0x61 [ 0.364022] PGD 0 [ 0.364022] Thread overran stack, or stack corrupted config, log and bzImage can be found here: http://redhat.com/~mingo/misc/config-Thu_Jun_19_12_10_40_CEST_2008.bad http://redhat.com/~mingo/misc/crash-Thu_Jun_19_12_10_40_CEST_2008.log http://redhat.com/~mingo/misc/bzImage-Thu_Jun_19_12_10_40_CEST_2008.bad reverting your patch fixes the crash. if you have trouble reproducing the problem then you should be able to stick the bzImage into any 64-bit PC's /etc/grub.conf (no initrd needed) and it should just crash straight away during bootup. NOTE: -tip auto-testing randomizes various commonly used boot parameters as well, you can find them in the bootup log: root=/dev/sda6 console=ttyS0,115200 earlyprintk=serial,ttyS0,115200 debug initcall_debug apic=verbose sysrq_always_enabled ignore_loglevel selinux=0 maxcpus=1 nosmp no_hz=off highres=0 nmi_watchdog=0 noapic nolapic_timer hpet=disable idle=mwait idle=poll highmem=512m nopat notsc acpi=off pci=nomsi this might be material to reproducing the crash. NOTE2: the bzImage above will have the above boot parameters auto-appended, no need for you to configure them. But if you build your own kernel from tip/master using the above config you might have to add these boot parameters to the 'kernel' line of /etc/grub.conf to reproduce the crash. Ingo