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    SubjectRe: 2.6.39-rc4 BUG: unable to handle kernel NULL pointer dereference at 0000000c IP: cfq_insert_request+0x1d/0x3f5
    On 2011-04-22 09:00, Michal Hocko wrote:
    > On Thu 21-04-11 21:00:26, Jens Axboe wrote:
    >> On 2011-04-21 20:51, Michal Hocko wrote:
    >>> On Thu 21-04-11 07:38:57, Linus Torvalds wrote:
    >>>> On Thu, Apr 21, 2011 at 12:25 AM, Jens Axboe <> wrote:
    >>>>>> I am going to bisect, let's see if I can find anything.
    >>>>> Thanks, that would be great!
    >>>> I'd expect it to be very timing-dependent, and thus could easily be
    >>>> triggered (or hidden) by unrelated changes.
    >>>> Just happening to have a request added to the elevator at _just_ the
    >>>> same moment that another CPU is changing it and getting rid of the
    >>>> data structures for the old one.
    >>> And it really looks like a timing issue. I have bisected down to
    >>> e710d7d5a9cab1041b7a3cf9e655b75d92786857. I had to skip[1] some commits
    >>> due to compile errors [2].
    >>> At first it looked quite promising because I was able to boot after I
    >>> reverted that patch but then I have tried to revert it on top of rc4
    >>> (2f666bcf757cb72549f360ef6da02f03620a48b6) and saw the same problem
    >>> again.
    >>> So I do not think that bisecting will help here.
    >> It will be timing dependent. If there's no allocated IO requests when
    >> the switch happens, it'll work.
    >> But the commit that caused this regression is 5e84ea3a. If you revert
    >> that, it should work fine. Or just apply the patch I sent (or update to
    >> Linus' tree, it's in now) and it'll work as well.
    > Great. I can boot just fine with the current Linus tree
    > (2.6.39-rc4-00149-g91e8549).
    > Thanks a lot!

    Great, with that confirmed from you, we have no pending bugs in this

    Jens Axboe

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      Last update: 2011-04-22 13:39    [W:0.024 / U:9.640 seconds]
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