Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753487AbZFSA37 (ORCPT ); Thu, 18 Jun 2009 20:29:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751458AbZFSA3v (ORCPT ); Thu, 18 Jun 2009 20:29:51 -0400 Received: from claw.goop.org ([74.207.240.146]:46064 "EHLO claw.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751075AbZFSA3v (ORCPT ); Thu, 18 Jun 2009 20:29:51 -0400 Message-ID: <4A3ADBFA.1060702@goop.org> Date: Thu, 18 Jun 2009 17:29:46 -0700 From: Jeremy Fitzhardinge User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1b3pre) Gecko/20090513 Fedora/3.0-2.3.beta2.fc11 Lightning/1.0pre Thunderbird/3.0b2 MIME-Version: 1.0 To: Steven Rostedt CC: Jake Edge , LKML , Ingo Molnar , Frederic Weisbecker Subject: Re: problem with function_graph self-test? References: <20090616122603.6a628097@chukar> In-Reply-To: X-Enigmail-Version: 0.96a 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: 2804 Lines: 69 On 06/17/09 20:24, Steven Rostedt wrote: > On Tue, 16 Jun 2009, Jake Edge wrote: > > >> Hi Steve, >> >> This has taken me a bit to track down ... I built a kernel from Linus's >> git tree (as of this morning: commit >> 03347e2592078a90df818670fddf97a33eec70fb) and when i boot it, it locks >> up hard giving me a cursor in the upper left (which seems to grow then >> shrink once, if that tells anyone anything) and no other output ... i >> started messing with kernel params (turning off quiet, rhgb, adding >> boot_delay and, eventually figuring out i needed lpj as well) to try >> and extract some info ... it seems to reliably fail in the >> function_graph tracer self-test with a variety of messages (I >> unfortunately don't have a serial console on the laptop that I am >> using) ... two of the messages that I got (possibly from different >> boots): >> >> BUG: unable to handle kernel NULL pointer dereference at 00000048 >> BUG: Function graph tracer hang! >> >> I can try and get more information, but I wanted to check first if you >> already know about this ... somehow i'll either need to type faster :) >> or reliably slow it down and take pictures, which I can do if you'd >> like ... >> >> obviously, for my purposes, i can turn off the selftests and/or the >> function_graph tracer ... >> > > Jake, when you find a bug, you really find a bug! > > This is something that gcc is screwing with us. After spending all day > today trying to figure out what is happening, I finally found it in the > assembly. > > In the timer_stats_update_stats function, I get this at the beginning: > > 00000327 : > 327: 57 push %edi > 328: 8d 7c 24 08 lea 0x8(%esp),%edi > 32c: 83 e4 e0 and $0xffffffe0,%esp > 32f: ff 77 fc pushl 0xfffffffc(%edi) > 332: 55 push %ebp > 333: 89 e5 mov %esp,%ebp > 335: 57 push %edi > 336: 56 push %esi > 337: 53 push %ebx > 338: 81 ec 8c 00 00 00 sub $0x8c,%esp > 33e: e8 fc ff ff ff call 33f > 33f: R_386_PC32 mcount > > > And this at the end of the function: > > 4f6: 8d 67 f8 lea 0xfffffff8(%edi),%esp > 4f9: 5f pop %edi > 4fa: c3 ret > Something to do with using _RET_IP_ in spin_unlock_irqrestore() perhaps? J -- 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/