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SubjectRe: [Bug 11506] oops during unmount - ext3? (2.6.27-rc5)
> On Sun, Sep 07, 2008 at 01:27:40PM +0200, Marcin Slusarz wrote:
> > Code: 8b 06 a8 01 75 04 0f 0b eb fe f6 c4 08 0f 84 2f 03 00 00 48 8b 45 b8 48 8b 40 10 c7 45 c8 01 00 00 00 48 89 45 d0 48 89 c3 31 c0 <8b> 53 20 01 c2 89 c0 48 39 45 b0 89 55 cc 48 9b 53 08 48 89 55
> Little correction (at the end):
> Code: 8b 06 a8 01 75 04 0f 0b eb fe f6 c4 08 0f 84 2f 03 00 00 48 8b 45 b8 48 8b 40 10 c7 45 c8 01 00 00 00 48 89 45 d0 48 89 c3 31 c0 <8b> 53 20 01 c2 89 c0 48 39 45 b0 89 55 cc 48 8b 53 08 48 89 55
>
> > Output of decodecode:
> After correction:
> /tmp/tmp.W6DvY3Lbtg.o: file format elf64-x86-64
>
> Disassembly of section .text:
>
> 0000000000000000 <.text>:
> 0: 8b 06 mov (%rsi),%eax
> 2: a8 01 test $0x1,%al
> 4: 75 04 jne 0xa
> 6: 0f 0b ud2a
> 8: eb fe jmp 0x8
> a: f6 c4 08 test $0x8,%ah
> d: 0f 84 2f 03 00 00 je 0x342
> 13: 48 8b 45 b8 mov -0x48(%rbp),%rax
> 17: 48 8b 40 10 mov 0x10(%rax),%rax
> 1b: c7 45 c8 01 00 00 00 movl $0x1,-0x38(%rbp)
> 22: 48 89 45 d0 mov %rax,-0x30(%rbp)
> 26: 48 89 c3 mov %rax,%rbx
> 29: 31 c0 xor %eax,%eax
>
> /tmp/tmp.W6DvY3Lbtg.o: file format elf64-x86-64
>
> Disassembly of section .text:
>
> 0000000000000000 <.text>:
> 0: 8b 53 20 mov 0x20(%rbx),%edx
> 3: 01 c2 add %eax,%edx
> 5: 89 c0 mov %eax,%eax
> 7: 48 39 45 b0 cmp %rax,-0x50(%rbp)
> b: 89 55 cc mov %edx,-0x34(%rbp)
> e: 48 8b 53 08 mov 0x8(%rbx),%rdx
> 12: 48 rex.W
> 13: 89 .byte 0x89
> 14: 55 push %rbp
Hmm, from this disassembly it seems that somebody has overwritten our
page->private pointer to 1000c20d02020000 and then we obviously failed
to get bh->b_size. But I don't really see how this can happen. What also
puzzles me a bit is that I don't see BUG_ON(!PagePrivate(page)) in the
disassembly but it should be there because of page_buffers()
implementation... Anyone has an idea?

Honza
--
Jan Kara <jack@suse.cz>
SuSE CR Labs


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