Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757952AbaGWOiO (ORCPT ); Wed, 23 Jul 2014 10:38:14 -0400 Received: from darkcity.gna.ch ([195.226.6.51]:50041 "EHLO mail.gna.ch" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756831AbaGWOiL (ORCPT ); Wed, 23 Jul 2014 10:38:11 -0400 Message-ID: <53CFC8C8.3070304@daenzer.net> Date: Wed, 23 Jul 2014 23:38:00 +0900 From: =?windows-1252?Q?Michel_D=E4nzer?= User-Agent: Mozilla/5.0 (X11; Linux ppc; rv:31.0) Gecko/20100101 Icedove/31.0 MIME-Version: 1.0 To: Peter Zijlstra , Dietmar Eggemann CC: Linus Torvalds , Ingo Molnar , Linux Kernel Mailing List Subject: Re: Random panic in load_balance() with 3.16-rc References: <53CF31AE.30403@daenzer.net> <20140723064948.GK3935@laptop> <53CF6CC4.6090207@daenzer.net> <20140723082819.GR3935@laptop> <20140723092536.GO12054@laptop.lan> <53CF80EE.5050702@daenzer.net> <53CF844A.5050106@arm.com> <20140723111110.GT3935@laptop> <20140723113021.GP12054@laptop.lan> <20140723142454.GQ12054@laptop.lan> In-Reply-To: <20140723142454.GQ12054@laptop.lan> X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 23.07.2014 23:24, Peter Zijlstra wrote: > On Wed, Jul 23, 2014 at 01:30:21PM +0200, Peter Zijlstra wrote: >> On Wed, Jul 23, 2014 at 01:11:10PM +0200, Peter Zijlstra wrote: >>> On Wed, Jul 23, 2014 at 10:45:46AM +0100, Dietmar Eggemann wrote: >>>> Doesn't the picture showing the captured panic reveal more information. >>>> Haven't seen it myself, I just saw Peter's reply to your email >>> >>> Its a general protection fault from somewhere in load_balance(), I send >>> you the picture. >>> >>> It would help to get addr2line of the RIP I suppose. >>> >>> Michel provided a config, so lemme go try and build that, maybe my gcc >>> will generate similar code to his and the function offset is enough >>> clue. >> >> So the code section says the faulting instruction is: >> >> f3 a5 >> >> followed by: >> >> 48 89 c7 85 50 ff ff >> >> or so. >> >> My compiled code is 'different', the function is shorter, but there's a >> f3 a5 somewhere not too far short of +d7 at +a8. I have (objdump -SD): >> >> 35a8: f3 a5 rep movsl %ds:(%rsi),%es:(%rdi) >> >> for_each_cpu_and(i, sched_group_cpus(group), env->cpus) { >> unsigned long capacity, capacity_factor, wl; >> enum fbq_type rt; >> >> rq = cpu_rq(i); >> 35aa: 48 c7 c1 00 00 00 00 mov $0x0,%rcx >> >> And that's the only part that could possibly match. >> >> That looks like the start of find_busiest_queue(). I'm not entirely sure >> what the rep movsl is operating on, lemme try and figure that out. > > Ah, this appears to be load_balance()'s: > > cpumask_copy(cpus, cpu_active_mask); Right, according to addr2line it's the memcpy in bitmap_copy(). > Which totally doesn't make sense, both src and dst are static storage. > Dst is the most interesting since its per-cpu storage, but still. > > No way either of those should generate a #GP. Puzzled. Could it be the memcpy length being off or something like that? -- Earthling Michel D?nzer | http://www.amd.com Libre software enthusiast | Mesa and X developer -- 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/