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    SubjectRe: BUG: Bad page map in process udevd (anon_vma: (null)) in 2.6.38-rc4
    From
    From: Linus Torvalds <torvalds@linux-foundation.org>
    Date: Thu, 17 Feb 2011 20:30:42 -0800

    > On Thu, Feb 17, 2011 at 7:16 PM, Eric W. Biederman
    > <ebiederm@xmission.com> wrote:
    >> BUG: unable to handle kernel paging request at ffff8801adf8d760
    >> IP: [<ffffffff8140c7ca>] unregister_netdevice_queue+0x3a/0xb0
    >
    > Yup. That's the "list_move()". The disassembly is exactly what I'd
    > expect from __list_del():
    >
    > 16: 48 8b 93 a0 00 00 00 mov 0xa0(%rbx),%rdx
    > 1d: 48 8b 83 a8 00 00 00 mov 0xa8(%rbx),%rax
    > 24: 48 8d bb a0 00 00 00 lea 0xa0(%rbx),%rdi
    > 2b:* 48 89 42 08 mov %rax,0x8(%rdx) <-- trapping instruction
    > 2f: 48 89 10 mov %rdx,(%rax)
    >
    > So I think we can consider this confirmed: it really is the stale
    > queue left over on the stack (introduced by commit 443457242beb). With
    > CONFIG_DEBUG_PAGEALLOC, you get a page fault when it tries to update
    > the now stale pointers.
    >
    > The patch from Eric Dumazet (which adds a few more cases to my patch
    > and hopefully catches them all) almost certainly fixes this rather
    > nasty memory corruption.

    Eric D., please get a final version of the fix posted to netdev and
    I'll make sure it slithers it's way to Linus's tree :-)

    Thanks!


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