Re: Linux 2.6.38-rc6
From: Anca Emanuel
Date: Thu Feb 24 2011 - 20:48:10 EST
On Fri, Feb 25, 2011 at 3:14 AM, Dave Airlie <airlied@xxxxxxxxxx> 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@xxxxxxxxx> 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.
Tested Andy's patch and it works !
Tested-by: Anca Emanuel <anca.emanuel@xxxxxxxxx>
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