very old display driver bug?

[gregrwm]

the most bothersome, most notable, and most curious symptom of this bug is the absolute degree to which the display locks up. xclock's seconds are no longer changing, the mouse cursor won't move, and even ctl-alt-F1 does nothing.

meanwhile mplayer, playing in a hidden tmux window, is still playing merrily along.

i logged in via sshd and copied this from htop:
0 [|||||||||||||||||||||||||||||||||||||||||100.0%] Tasks: 68; 3 running
1 [|| 1.3%] Load average: 1.00 0.91 0.53
Mem[|||||||||||||||||||||||||||||||||||||973M/1.91G] Time: 14:26:17
Swp[ 0K/1.86G]
  PID START USER VIRT RES NI CPU% TIME+ S Command
 1714 12:50 g 1713M 789M 0 0.0 6:37.92 S /usr/lib/firefox/firefox
 2368 14:07 g 661M 57252 0 0.0 0:03.33 S /usr/bin/python3 /usr/bin/blueman-manager
  794 12:49 root 269M 54988 0 99.3 10:12.88 R /usr/lib/xorg/Xorg -core :0 -seat seat0 -auth /var/
 2385 14:07 g 583M 53524 0 0.0 0:00.39 S /usr/bin/python3 /usr/bin/blueman-applet
 2397 14:07 g 555M 42968 0 0.0 0:10.68 S pavucontrol
 1926 12:57 g 282M 37752 0 0.7 0:02.46 S /usr/lib/firefox/plugin-container /opt/google/talkp
 1933 12:57 g 512M 36404 0 0.0 0:02.96 S /opt/google/talkplugin/GoogleTalkPlugin
 2403 14:07 g 823M 30352 0 0.0 0:03.52 S mplayer -ao pulse -af channels=2 -framedrop -msgcol
F1Help F2Setup F3SearchF4FilterF5Tree F6SortByF7Nice -F8Nice +F9Kill F10Quit

ps also attached, taken before killing xorg.

i've filed this under xorg merely because xorg is the one stuck eating all the CPU. i really suspect the display driver, and don't know how to find or identify that.

i much more commonly saw these very same symptoms when i used to run xscreensaver. i stopped running xscreensaver just to stop beating my head against that wall. but many years and many releases later, it looks like this display driver bug is still lurking around.

there was hardly anything running when this froze. i already mentioned mplayer (sound only) and tmux, twm's the window manager, firefox was running but iconized and idle tho running gmail and the googletalk plugin, not that i suspect any of them in any way. xterm was occupying most of the screen, showing tmux, and idle. the ones i'd more suspect would be xclock & pavucontrol. pavucontrol was hidden but busily showing it's audio level bar, xclock was visible and displaying the time of day including seconds, so the most likely one to have tripped a display driver bug.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: xorg 1:7.7+13ubuntu3
ProcVersionSignature: Ubuntu 4.4.0-47.68-generic 4.4.24
Uname: Linux 4.4.0-47-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
Date: Mon Nov 28 14:36:38 2016
InstallationDate: Installed on 2016-10-15 (43 days ago)
InstallationMedia: Lubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160720)
SourcePackage: xorg
UpgradeStatus: No upgrade log present (probably fresh install)

[gregrwm (gregrwm)]

in all of the following bugs, xorg either crashes or hangs, and ctl-alt-Fn either doesn't respond (ie loss of ability to change virtual terminal from the keyboard) or in Bug #1290797 the text gets switched but not the mouse cursor function.

Bug #1757299 xorg hangs
Bug #1744429 xorg sometimes freezes up while playing either vlc or youtube
Bug #1645485 very old display driver bug?
Bug #1290797 longstanding display driver bug elicited by xscreensaver or lightdm or chvt

i have xdiagnose installed in bionic, ready for the next occurrence.

[penalvch (penalvch)]

gregrwm, reviewing your attachments, your crash report is missing, and no useful information is provided to root cause this problem.

Please follow these instructions to have apport report a new bug against your crash file that can be dealt with by the automatic retracer. First, execute at a terminal:
cd /var/crash && sudo rm * ; sudo apt-get update && sudo apt-get -y dist-upgrade && sudo service apport start force_start=1

If you are running the Ubuntu Stable Release you might need to enable apport in /etc/default/apport and restart. Now reproduce the crash, then open a terminal, navigate to your /var/crash directory and file your report with:
sudo ubuntu-bug /var/crash/_my_crash_report.crash

where _my_crash_report.crash is the crash you would like to report. By default, this sends the crash to the Ubuntu Error Tracker infrastructure, which is different than Launchpad. For more on this, please see https://wiki.ubuntu.com/ErrorTracker .

However, this report is being closed since the process outlined above will deal with this issue more efficiently.

Also, please do not attach your crash report manually to this report and reopen it.

Thank you for your help.

Helpful bug reporting tips:
https://wiki.ubuntu.com/ReportingBugs

[gregrwm (gregrwm)]

when Xorg hangs but does not crash, as in this bug description, will a manual kill of Xorg, perhaps with a certain signal, produce the crash report you describe?

[penalvch (penalvch)]

gregrwm, the bug scoped to xorg hanging is handled in LP#1757299.