Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965123Ab3GLRCS (ORCPT ); Fri, 12 Jul 2013 13:02:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40023 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965103Ab3GLRCR (ORCPT ); Fri, 12 Jul 2013 13:02:17 -0400 Date: Fri, 12 Jul 2013 13:00:46 -0400 From: Dave Jones To: Steve Wise Cc: linux-kernel@vger.kernel.org Subject: Re: Oops mystery Message-ID: <20130712170046.GB1537@redhat.com> Mail-Followup-To: Dave Jones , Steve Wise , linux-kernel@vger.kernel.org References: <51E02545.7080106@opengridcomputing.com> <20130712164816.GE1020@redhat.com> <51E0348A.2030208@opengridcomputing.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <51E0348A.2030208@opengridcomputing.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1483 Lines: 39 On Fri, Jul 12, 2013 at 11:53:30AM -0500, Steve Wise wrote: > On 7/12/2013 11:48 AM, Dave Jones wrote: > > On Fri, Jul 12, 2013 at 10:48:21AM -0500, Steve Wise wrote: > > > > > So 'movb $0x0,0xe(%rax,%rdx,1)' should be storing 0 into the byte > > > location: > > > > > > %rax + 0xe + (%rdx * 1) == > > > 0x40fc+ 0xe + 0xffff8808b5500000 == > > > 0xffff8808b5540fce. > > > > > > That address is readable in the crash dump: > > > > > > crash> x/8b 0x0000000000040fc0+0xe+0xffff8808b5500000 > > > 0xffff8808b5540fce: 0x00 0x00 0x00 0x00 0x00 0x00 > > > 0x00 0x00 > > > > > > And why does the page fault show 0x40fc0 as the faulting address? It > > > should be 0xffff8808b5540fce and it shouldn't have caused a page fault. > > > > > > What am I missing? > > > > Random guess: Is that page marked read-only perhaps ? > > It shouldn't be. :) How can I get this info via the crash dump? The > memory was allocated with dma_alloc_coherent(). Why would the page > fault occur on 0x40fc0 though? That makes me think my analysis so far > is incorrect. Hmm, good point. Do you have the Code: line from the oops ? Does that match the disassembly ? Dave -- 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/