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    SubjectRe: Linux 2.6.38-rc6
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    On Fri, Feb 25, 2011 at 3:47 AM, Anca Emanuel <anca.emanuel@gmail.com> wrote:
    > On Fri, Feb 25, 2011 at 3:14 AM, Dave Airlie <airlied@redhat.com> wrote:
    >> On Thu, 2011-02-24 at 16:54 -0800, Linus Torvalds wrote:
    >>> On Thu, Feb 24, 2011 at 4:48 PM, Anca Emanuel <anca.emanuel@gmail.com> wrote:
    >>> >
    >>> > diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
    >>> > index e2bf953..e8f8925 100644
    >>> > --- a/drivers/video/fbmem.c
    >>> > +++ b/drivers/video/fbmem.c
    >>> > @@ -1511,6 +1511,7 @@ void remove_conflicting_framebuffers(struct
    >>> > apertures_struct *a,
    >>> >                               "%s vs %s - removing generic driver\n",
    >>> >                               name, registered_fb[i]->fix.id);
    >>> >                        unregister_framebuffer(registered_fb[i]);
    >>> > +                       registered_fb[i] = NULL;
    >>> >
    >>> > Tested the patch, and now I get this:
    >>> > dmesg: http://pastebin.com/ieMNrA7C
    >>> >
    >>> > [   12.252328] BUG: unable to handle kernel NULL pointer dereference
    >>> > at 00000000000003b8
    >>> > [   12.252342] IP: [<ffffffff81311178>] fb_mmap+0x58/0x1d0
    >>>
    >>> Ok, goodie.
    >>>
    >>> Or not so goodie, but it does make it clear that yeah, the fb code
    >>> seems to be using stale pointers from that registered_fb[] array, and
    >>> the whole unregistration process is just racing with people using it.
    >>>
    >>> Herton had that much bigger patch, can you test it?
    >>
    >> I think Andy's patch worked, not sure why it fell between the cracks,
    >> either didn't appear on lkml or in my inbox at all.
    >>
    >> if we can get Herton to repost it properly + a tested by I'm happy for
    >> it to go in.
    >>
    >> Dave.
    >>
    >>
    >
    > Tested Andy's patch and it works !
    > http://kernel.ubuntu.com/git?p=ubuntu/ubuntu-natty.git;a=commit;h=c5a742b5f78e161d6a13853a7e3e6e1dfa429e69
    >
    > Tested-by: Anca Emanuel <anca.emanuel@gmail.com>
    >

    link to patch: http://is.gd/otIfGc
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