Compiz Crashed with SIGSEGV [Radeon]

[Liam McDonagh-Greaves]

SEE WORKAROUND AT END OF POST

Symptoms:
On login, the desktop takes a long time to load, and when it does, everything blinks. It is possible (but difficult) to open a terminal and execute commands, through the right-click desktop menu.

I first noticed the issue in mid-July of 2018.

System:
Acer 5100
Ubuntu 16.04 (64-bit)
Graphics card: VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] RS482M [Mobility Radeon Xpress 200]

Believed to be mesa-related, as symptoms very similar to bug #1741447 and #1735594. I have been informed by a mesa developer that my issue is different because that bug affects Intel GPUs. This system has a Radeon GPU.

Log files are as attached to bug #1795709. That bug was declared invalid by Apport because it says I don't have the necessary debug packages installed. However, I could not find the debug packages in the repository, so that is why I am submitting this report manually.

Many thanks for any help.

Edit 29/12/2018:
WORKAROUND
This bug is still present. However, I present a workaround. It is aimed at relatively inexperienced users like me. It guides the user through downgrading/rolling back affected packages to the most recent known working versions.
1. Navigate to /var/log/apt in a file explorer. Open the logs until you find the offending mesa updates. In my case, the updates were installed on 15/07/18.
2. Copy and paste the log into a text file on your desktop. Close the log.
3. In the text file, do a ctrl+F search on "mesa" to highlight all instances of mesa-related packages. Keep these lines and delete the others. Each line should have this kind of format:
  libgles2-mesa:amd64 (17.2.8-0ubuntu0~16.04.1, 18.0.5-0ubuntu0~16.04.1) (exact package name/version numbers may differ). The first number in brackets is the version of the package that you had before, the second number is the version it was upgraded to. You should end up with a list of such lines.
4. The earlier versions of these packages can be downloaded from Launchpad. I don't know how to find them using links/searches, but the URLs look like this:
https://launchpad.net/ubuntu/xenial/amd64/libgles2-mesa/17.2.8-0ubuntu0~16.04.1. You will have to alter the url according to your architecture, package name and package version required.
5. You will see a page with a download link on the right-hand side for a .deb file. Make a new folder on your desktop called "mesa-install" and download the .deb file there.
6. Scroll down, and on the left, you will see any dependencies of this package. If any of them say "<package name> (=version number)" then you must make a note of these packages on your list of packages to download and install. If they have a ">=" sign, or no version number given, ignore them.
7. Repeat steps 4 - 6 for all the packages on your list, placing the .deb files in the "mesa-install" folder.
8. MAKE SURE ALL IMPORTANT FILES ON YOUR SYSTEM ARE BACKED UP.
9. Open a terminal (Ctrl + Alt + T).
10. Type "sudo dpkg -R --install /home/<username>/Desktop/mesa-install/
Replace "<username> with your username. This command installs all .deb files in that folder.
11. Reboot PC.
12. Log in to a Unity session. Rejoice in the fact that it now works (hopefully). Assuming it is now working, you need to make sure that the packages you downgraded are not subsequently upgraded automatically by Ubuntu. Ignore any offers of automatic updates until you have completed all the steps.
13. Open a terminal and type:
sudo apt-mark hold <package name>
where "<package name>" is the name of the first package you downgraded. Press enter, enter password, etc. You should receive confirmation that the package has been held.
14. Repeat step 13 for all packages on your list.

Good luck to all others who have faced this problem, and fingers crossed for a bug fix!

[Dash (devel-tootai)]

I have the same problem, needed datas were given at https://bugs.launchpad.net/ubuntu/+source/mesa/+bug/1741447/comments/68

Daniel