Re: Fw: 2.6.17 oops, possibly ntfs/mmap related

[Hugh Dickins <hugh@veritas.com>]

On Thu, 21 Sep 2006, Andrew Morton wrote:
> On Thu, 21 Sep 2006 15:41:36 +0100
> Anton Altaparmakov <aia21@cam.ac.uk> wrote:
> > 
> > BUG: unable to handle kernel paging request at virtual address 020030d2
> > 
> > The values of the relevant variables from the oops are:
> > 
> > page = 0xc2248fa0
> > page->mapping = 0xe3a79eac
> > page->mapping->a_ops = 0x020030aa
> 
> I wonder if page->mapping really wanted to be 0xc3a79eac, only something
> set bit 29.

Perhaps, but I'm more suspicious of that 0x0200 top half of the a_ops ptr.

> 
> > Note that 0x020030aa+0x28 = 020030d2 which is the oops causing address
> > and 0x28 is the offset of the releasepage function pointer in the
> > address space operations structure...
> > 
> > This oops is not identical to the oopses pointed out by Jonathan at:
> > 
> > http://www.atrad.com.au/~jwoithe/kernel/oopses-20060913.txt
> > 
> > But those oopses have to do with pages also so could be related...
> 
> Looks a bit different - Jonathan appears to have pulled a bad page* out
> of the radix tree whereas you got your page off the LRU.

Jonathan does show a second oops, from a later boot:

  BUG: unable to handle kernel paging request at virtual address 0010c744
   printing eip:
  c013be50
  *pde = 00000000
  Oops: 0002 [#1]
  Modules linked in: ntfs 8139too via_agp agpgart usb_storage ehci_hcd uhci_hcd usbcore
  CPU:    0
  EIP:    0060:[<c013be50>]    Tainted: G   M  VLI
  EFLAGS: 00010282   (2.6.17 #2) 
  EIP is at anon_vma_unlink+0x16/0x3c
  eax: 0010c740   ebx: cf1070cc   ecx: cf107104   edx: cf8bc740
  esi: cf8bc740   edi: b7e82000   ebp: 00000000   esp: cdad7f58

I haven't worked out the disassembly in detail to support the idea
(though certainly anon_vma_unlink would be trying to list_del around
here), but that eax and esi do suggest a corrupted list: somehow the
top half of a pointer overwritten by the top half of LIST_POISON1.

And in Anton's case, the top half of a pointer overwritten by the
bottom half of LIST_POISON2.

Maybe just coincidence, and I've nothing more illuminating to add;
but just a hint of a list_del going very wrong somewhere?

Hugh
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