Re: PROBLEM: kernel BUG at drivers/gpu/drm/drm_fops.c:146!

From: Dan Nicholson
Date: Thu Jan 29 2009 - 20:17:41 EST


On Thu, Jan 29, 2009 at 5:06 PM, Dave Airlie <airlied@xxxxxxxxx> wrote:
> On Fri, Jan 30, 2009 at 10:30 AM, Andrew Morton
> <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>> (cc's added)
>>
>> On Wed, 21 Jan 2009 13:27:48 +0100
>> Sami Kerola <kerolasa@xxxxxx> wrote:
>>
>>> I compiled the Torvalds git kernel 2.6.29-rc2-00013 and I got an oops.
>>> The oops happens when ever X starts. Initially I was booting with run
>>> level 5 and it hung. I tried to use run level to 3 and an operating
>>> system started just fine. When I type startx the hung happen again.
>>> Please let me know if you need some more information besides oops from
>>> messages file and lspci output.
>>>
>>>
>>> Jan 21 08:53:58 lelux kernel: ------------[ cut here ]------------
>>> Jan 21 08:53:58 lelux kernel: kernel BUG at drivers/gpu/drm/drm_fops.c:146!
>>
>> I assume that 2.6.28 didn't do this?
>
> This is a userspace race between udev and libdrm, I'm not sure we can do
> anything in the kernel other than BUG, maybe we should just WARN instead.
>
> Basically, libdrm creates devices nodes, the initial drm opening gets that, udev
> comes along when the module is loaded and re-creates the device node,
> when AIGLX opens the device
> it can't figure out wtf just happened, as the inode->i_mapping we use
> to store the GEM device mmap ranges is different.
>
> I think building libdrm with --enable-udev is the correct answer, and
> maybe switching this to a WARN so it doesn't blow up.

Hi Dave,

I really think libdrm should have --enable-udev on by default for
linux. The number of people not using udev for managing their devices
is surely in the minority now. What do you think?

--
Dan
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