linux-kernel - Re: Oops mystery

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Message-ID: <20130712164816.GE1020@redhat.com>
Date:	Fri, 12 Jul 2013 12:48:16 -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 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 ?

	Dave

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