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

[bugzilla-daemon at freedesktop.org]

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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