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    SubjectRe: Linux 2.6.38-rc6
    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?

    Linus
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