Bug 108106

Created attachment 141812 [details]
Full dmesg

Created attachment 141813 [details]
Content from /sys/class/drm/card0/error

Please note that during boot I see the following error message:

[    2.455186] [drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun
[    2.455228] [drm:intel_set_pch_fifo_underrun_reporting [i915]] *ERROR* uncleared pch fifo underrun on pch transcoder A                                                                                                         
[    2.455252] [drm:intel_pch_fifo_underrun_irq_handler [i915]] *ERROR* PCH transcoder A FIFO underrun

I never bothered about it previously because it does not prevent the system from booting and from displaying graphics.

Do you think it is related to my main graphic problem?

Created attachment 141814 [details]
Sample of corruption

Created attachment 141823 [details]
Other example of corruption

Hi Laurent,

Could you please describe actions after which you observed those hangs?
I've tried to reproduce this issue but couldn't catch anything like that for several hours using following environment:

SandyBridge; Intel® HD Graphics 3000; Intel Core i5-2520M;
Ubuntu 18.10 kernel 4.18.11-041811-generic; Plasma desktop;
Mesa-18.2.1;
X.Org 1.20.1

Hi Laurent,

Is this issue still actual for you? 
If so, could you please provide some description of actions which lead to this hang since I still faced no issues while use mentioned environment for several days.

>Could you please describe actions after which you observed those hangs?

I am using plasma with many (12) virtual desktops.  As constantly running applications, I use thunderbird, firefox, akregator and many konsoles.
The crucial point to reproduce this bug is to run plasma with compositing activated.
I will attach a screenshot of my settings.

>I've tried to reproduce this issue but couldn't catch anything like that for several hours 

Thanks for trying so hard!

Created attachment 142006 [details]
Compositor settings

> Is this issue still actual for you? 

Yes, even with recent updates:

Linux kernel 4.18.13-041813-generic
Mesa 18.2.2-0ubuntu1
libdrm 2.4.95-1

I even recorded a screenshot with more massive corruption.

Created attachment 142007 [details]
More massive corruption

The problem seems to come from glamor acceleration, since the problem seems to disappear when I disable graphic acceleration with the following configuration:

    Driver      "modesetting"
    Option      "AccelMethod"    "none"  # (instead of "glamor")

For the record, I am still seeing graphic corruption in Ubuntu 18.10 with those software versions:

Linux kernel 5.0.7
Mesa 18.2.8-0ubuntu0~18.10.2
libdrm 2.4.95-1
Xorg 1.20.3-0ubuntu0.18.10.1

I am going to upgrade my system to Ubuntu 19.04...

I also tested Fedora 29 on the same laptop and I also see graphic corruption:
 - in GNOME/Wayland
 - in Plasma/Xorg

hi, I also tried to load about 12 desktops with some apps (web gl in browser, a lot of cmd's, etc) - didn't see your's corruptions (few gpu hangs in web content, without any stable steps, that's all).
Config for Xorg is the same with your's - glamor enabled, driver is modesetting. 

I will try to work on this machine longer and update kernel.
Current setup is:

ubuntu 18.10
kernel 4.18
mesa 18.3.0

Thanks a lot for trying to reproduce this problem!

Sometimes it appears after a few minutes, sometimes it appears after a few hours.  One way to make it appear quicker is to enable compositing in Plasma.

Since I seem to be the only one to have this problem, do you think it may be caused by a defective CPU/GPU? (it is very old by now)

I upgraded my Ubuntu system and I still see graphic corruption.  Here is version info:

Ubuntu 19.04
Linux kernel 5.0.7
Mesa 19.0.1-1ubuntu2
libdrm 2.4.97-1ubuntu1
Xorg 1.20.4-1ubuntu3

I started to see transient corruption after a few hours of work.  After ~20 hours, I get corruption in text for all newly started GTK3 applications (see screenshot).  Qt5 applications still look fine or have occasional transient corruption.

Created attachment 143937 [details]
Screenshot for Ubuntu 19.04 that shows text corruption in GTK3 applications

Hello, Laurent.
Could you, please, try to use Mesa with patch https://gitlab.freedesktop.org/mesa/mesa/merge_requests/520?

If it didn't help - please, provide an apitrace (https://apitrace.github.io/) of corrupted app

I upgraded my system with disco-proposed that contains a more recent Mesa version:

Mesa 19.0.2-1ubuntu1

I am still seeing graphic corruption.

Created attachment 143940 [details]
Graphic corruption in Ubuntu 19.04

Here is an example of corruption that I got only a few seconds after logging in.  It occurred both with Mesa 19.0.1 and 19.0.2.

OpenGL triangles are clearly visible.

Sometimes there is no corruption but when a rectangle is displayed it is decomposed into several triangles and there is enough delay between triangles to notice that the rectangle is not displayed atomically.

My SandyBridge laptop died and my new laptop with a more recent CPU/GPU does not suffer from the same problem.  Therefore, I will not be able to do further tests concerning this bug.
Should I close this bug?