From: Dave Jones <davej@redhat.com>
To: Steve Wise <swise@opengridcomputing.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Oops mystery
Date: Fri, 12 Jul 2013 13:00:46 -0400 [thread overview]
Message-ID: <20130712170046.GB1537@redhat.com> (raw)
In-Reply-To: <51E0348A.2030208@opengridcomputing.com>
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
next prev parent reply other threads:[~2013-07-12 17:02 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-12 15:48 Oops mystery Steve Wise
2013-07-12 16:48 ` Dave Jones
2013-07-12 16:53 ` Steve Wise
2013-07-12 17:00 ` Dave Jones [this message]
2013-07-12 17:08 ` Steve Wise
2013-07-12 17:14 ` Dave Jones
2013-07-12 19:24 ` Steve Wise
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