i915 potential deadlock

[Saarinen, Jani]

Hi, 
> -----Original Message-----
> From: Intel-gfx <intel-gfx-bounces at lists.freedesktop.org> On Behalf Of
> Rodrigo Vivi
> Sent: Tuesday, 5 November 2024 4.34
> To: Coffin, Alexander <alex at cyberialabs.net>; Auld, Matthew
> <matthew.auld at intel.com>; Deak, Imre <imre.deak at intel.com>; Syrjala, Ville
> <ville.syrjala at intel.com>; Vishwanathapura, Niranjana
> <niranjana.vishwanathapura at intel.com>; andi.shyti at linux.intel.com
> Cc: intel-gfx at lists.freedesktop.org; Jani Nikula <jani.nikula at linux.intel.com>;
> Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Subject: Re: i915 potential deadlock
> 
> On Sat, Nov 02, 2024 at 01:46:15AM +0000, Alexander Coffin wrote:
> >    Hi Rodrigo,
> >
> >    > I'm sorry for that. Our list is moderated for non-subscribers because of
> >    the amount of spams we receive daily. But I eventually got to your msg and
> >    allowed it to go through.
> >
> >    I am sorry about sending the email twice in that case. In hindsight, I
> >    probably should have subscribed to the list and then sent the email to
> >    avoid this issue, but I don't interact with email lists that often so I
> >    didn't think of doing that.
> >
> >    > Could you please file a bug in our gitlab?
> >
> >    Of course.
> >    [1]https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/12677
> 
> Very interesting race...
> 
> Bringing some folks here that could have some ideas. I don't believe that we
> should be accepting that plane pin call before we finish the probe's initial plane
> object.
> 
> Folks, any quick idea?
Let's continue discussion at [1] as it has comments from Jani N already. 
 
Br,
Jani
> >
> >    > Well, so many things changed from 6.1... Is it possible to test with a
> >    drm-tip kernel and see if it is still reproduced?
> >
> >    Sorry, I mispoke in my last email that 6.1 is the latest LTS release. 6.6
> >    is the latest LTS release. 6.1 is the default for Debian though and isn't
> >    considered old there, and that is the kernel that I use on my personal
> >    desktop, personal laptop, server, and work laptop.
> 
> Nevermind. This part of the code hasn't changed since 6.1, so we likely still
> have this bug.
> 
> We usually ask to test a recent kernel so it is easier to backport some know fix.
> But this is not the case.
> 
> >
> >    I was hoping that this bug could be debugged (or at least attempted) with
> >    a single deadlock report (that has worked well most other times I have
> >    reported similar issues to kernel maintainers for other drivers).
> >
> >    If I knew how to recreate this issue I would gladly try out any kernel
> >    version for a quick test. Or if you have any things that you specifically
> >    want me to test then I would be happy to try a newer kernel version.
> >    However, I am not really comfortable daily driving a bleeding edge kernel
> >    version on my work laptop as of right now. I may be able to read through
> >    the source code to try to understand what could be triggering this issue
> >    and then figure out how to use that information to recreate it on a newer
> >    version, but as I don't think I have seen the issue since I reported it
> >    I'm not sure how likely it is that I stumble upon the issue by chance
> >    again. I would feel comfortable daily driving random kernels on my
> >    personal laptop, but I use an XPS 9370 for my personal laptop and I
> >    believe an XPS 15 9530 at work (if this is helpful information I can
> >    double check this and provide more system details) so they aren't the same
> >    hardware (I have no idea if the hardware is relevant).
> >
> >    Do you know where I could find information on the versions supported by
> >    Intel of the i915 driver? I can't seem to find anything from doing a few
> >    minutes of Google searching.
> >
> >    Best wishes,
> >
> >    Alex Coffin
> >
> > References
> >
> >    Visible links
> >    1. https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/12677