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Message-ID: <20130712170046.GB1537@redhat.com> Date: Fri, 12 Jul 2013 13:00:46 -0400 From: Dave Jones <davej@...hat.com> To: Steve Wise <swise@...ngridcomputing.com> Cc: linux-kernel@...r.kernel.org Subject: Re: Oops mystery 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@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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