From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1751675Ab2LOTny (ORCPT <rfc822;w@1wt.eu>);
	Sat, 15 Dec 2012 14:43:54 -0500
Received: from terminus.zytor.com ([198.137.202.10]:58962 "EHLO mail.zytor.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1751365Ab2LOTnx (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Sat, 15 Dec 2012 14:43:53 -0500
Message-ID: <50CCD24F.9090603@zytor.com>
Date: Sat, 15 Dec 2012 11:41:03 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0
MIME-Version: 1.0
To: Linus Torvalds <torvalds@linux-foundation.org>
CC: Markus Trippelsdorf <markus@trippelsdorf.de>,
        Jan Beulich <jbeulich@suse.com>, Matt Fleming <matt.fleming@intel.com>,
        David Howells <dhowells@redhat.com>,
        Grant Likely <grant.likely@secretlab.ca>,
        Guennadi Liakhovetski <g.liakhovetski@gmx.de>,
        Arnd Bergmann <arnd@arndb.de>, Dave Jones <davej@redhat.com>,
        Ingo Molnar <mingo@elte.hu>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Michael Kerrisk <mtk.manpages@gmail.com>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [GIT PULL] x86/uapi for 3.8
References: <201212122211.qBCMBRxl027895@terminus.zytor.com> <23916.1355356085@warthog.procyon.org.uk> <CA+55aFwBh3SY-K_dqdjpqyiBE+_PzbjMc=Qnt-QU9LNaK325TA@mail.gmail.com> <21507.1355528749@warthog.procyon.org.uk> <CA+55aFw34Nwi_aNjN-jm4SHkvT5659_aNVVmvARTCg5=9K0cZg@mail.gmail.com> <CA+55aFytC4xktWHAfQ96cdbt5nu+qbYytUGky8wWAkxZE=J0kw@mail.gmail.com> <CA+55aFyd5O_GyB_+BgHVYNLW-DV8xMQ9LOgPU34AtCqVvzfDaQ@mail.gmail.com> <20121215163323.GA229@x4> <CA+55aFz3iLPT3wzbU_Nhh4ft1eNQcd4WdQXsgXnKBs6vG9a_Uw@mail.gmail.com>
In-Reply-To: <CA+55aFz3iLPT3wzbU_Nhh4ft1eNQcd4WdQXsgXnKBs6vG9a_Uw@mail.gmail.com>
X-Enigmail-Version: 1.4.6
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 12/15/2012 10:35 AM, Linus Torvalds wrote:
> On Sat, Dec 15, 2012 at 8:33 AM, Markus Trippelsdorf
> <markus@trippelsdorf.de> wrote:
>> On 2012.12.14 at 17:47 -0800, Linus Torvalds wrote:
>>>
>>> Ho humm. Anybody else see anything strange?
>>
>> Yes. I'm seeing a BUG early during boot on my machine (RIP=NULL):
>>
>>  BUG: unable to handle kernel NULL pointer dereference at           (null)
>>
>> This is caused by commit 53b87cf088e2 ("x86, mm: Include the
>> entire kernel memory map in trampoline_pgd")
> 
> Hmm. That reverts cleanly, and the result boots fine for me. And the
> commit looks like exactly the kind of thing that could result in
> problems with exactly the right memory layout, so it could explain why
> the bisect failed and some kernels randomly worked for me and others
> didn't.
> 
> So this at least looks like a very possible candidate.
> 
> Does anybody have an explanation for the problem?
> 
> Btw. the machine in question does not have EFI, and is a bog-standard
> PC (DMI string: "P7H57D-V EVO, BIOS 0999 01/19/2010")
> 
> Matt? Jan?
> 

Matt is on vacation, and I'm partly offline for the weekend, but that
definitely seems suspicious.  Do we have a memory map of the affected
machine(s)?

	-hpa