Nouveau - Apr 2018 - [Bug 106294] New: GM204/modesetting DDX: Odd corruption (red backgrounds) introduced by Mesa

https://bugs.freedesktop.org/show_bug.cgi?id=106294

            Bug ID: 106294
           Summary: GM204/modesetting DDX: Odd corruption (red
                    backgrounds) introduced by Mesa
           Product: Mesa
           Version: git
          Hardware: x86-64 (AMD64)
                OS: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Drivers/DRI/nouveau
          Assignee: nouveau at lists.freedesktop.org
          Reporter: freedesktop-bugs at theblob.org
        QA Contact: nouveau at lists.freedesktop.org

I apologise if I have selected the wrong product for this bug, as I think I
probably have. If I need to open a new bug, please let me know.

I use an NVidia GeForce GTX 970, with kernel version 4.15.4-gentoo and the
modesetting driver in Xorg. (More detailed descriptions of packages installed
at the bottom of this description.)

My distribution (Gentoo) has packages for Mesa 17.2.8, 17.3.8, and a few other
higher versions (currently marked as unstable). When I use Mesa 17.3.8 or
higher, I see odd types of corruption involving red backgrounds on menus and
widgets, and some checkboxes appear unticked when they should be ticked. I
recorded this behaviour using OBS:

* Incorrect behaviour on 17.3.8 and higher:
    https://www.youtube.com/watch?v=puSC7a_osw0

* Expected behaviour on 17.2.8:
    https://www.youtube.com/watch?v=LbjCoIX4DKE

I dug out git and have confirmed that the bug still exists as of commit
https://cgit.freedesktop.org/mesa/mesa/commit/?id=8b7358fe4376aecee0c29ea622f88f9ef07e6b11
(the latest commit on master as of an hour ago or so).

After bisection, I discovered that the bug was introduced by
https://cgit.freedesktop.org/mesa/mesa/commit/?id=fcbb93e860246375d03f280f927f79d3645a8988
, which is actually *before* the 17.2.x branchpoint. It turns out that this
commit was reverted in the 17.2.x branch in commit
https://cgit.freedesktop.org/mesa/mesa/commit/?id=17a3e4891bf4fa09785fe9d22db5c79a949004db
to fix bug #101983. This was not committed to the 'master' branch, as
the fixes
in master apparently would have been rather invasive. This explains why my
tests of 17.2.8 worked fine.

This issue only appears when using the "modesetting" DDX drivers. When
using
the "nouveau" DDX drivers, the issue does not appear. (The
"nouveau" DDX
drivers also fix other issues for me so I'll probably switch to using that
from
now on for normal use, but I'm willing to switch back to help debug this
issue
if needed.)

System summary:

I have the following graphics card, as shown by lspci
-nn:
> 01:00.0 VGA compatible controller [0300]: NVIDIA Corporation GM204 [GeForce
GTX 970] [10de:13c2] (rev a1)
I am running Gentoo Linux with the sys-kernel/gentoo-sources-4.15.4 kernel,
with the following (relevant) packages installed:

* x11-base/xorg-server-1.19.5-r1
* x11-base/xorg-drivers-1.19 (with VIDEO_CARDS="nouveau")

In my kernel configuration, CONFIG_DRM_NOUVEAU is set to "m".

Please let me know if you need any more information.

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https://bugs.freedesktop.org/show_bug.cgi?id=106294

--- Comment #1 from Sophie Hamilton <freedesktop-bugs at theblob.org> ---
I just realised I still have this bug open... since then I've switched
graphics
cards to an AMD card, so I can no longer test this bug or assist with
debugging. I apologise for this.

This bug may still be relevant, so I'll leave it up to you whether to close
it
or not. I'm sorry for the inconvenience!

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https://bugs.freedesktop.org/show_bug.cgi?id=106294

Ilia Mirkin <imirkin at alum.mit.edu> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|NEW                         |RESOLVED

--- Comment #2 from Ilia Mirkin <imirkin at alum.mit.edu> ---
Good choice with switching to AMD! Tell your friends, too.

There's some likelihood that this issue was fixed by a change to dealing
with
uniform buffer size changes on GM10x+, which could be consistent with the
change you bisected to.

Given that you can't repro anymore, and the likelihood of it being fixed,
I'm
going to close it.

[Also, in any case, I recommend using the nouveau ddx over modesetting. You get
to use a small, well-tested driver vs ... the mess that is GL.]

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