Comment 22 for bug 1757299

another occurrence, same symptoms, last evening, was watching a youtube video.

i logged in via ssh, attached to tmux, launched htop, and started killing as you requested, in the following order, usually signal 15 but sometimes 9 if so noted below, if the name is postfixed with -- that means the process did not disappear from htop, --Z means the "S" column in htop then showed a Z, ++ means it was immediately respawned:

pulseaudio
pavucontrol
bluetooth-manager
xclock
xterm (this one did disappear)
vncviewer
x-window-manager-- (ie twm)
accounts-daemon
bluman-applet
xterm--Z
firefox-esr
ssh
rtkit-daemon
systemd-udev++
systemd-logind++
ssh-agent--
systemd-timesyncd++
systemd-resolved++
cron
bluetoothd
systemd --user
polkitd
login -p

at this point the console blanked and presented a login prompt. ctl-alt-Fn still would not function, however i was able to login at the console and attach to tmux. xorg remained on the process list still consuming cpu as evident in the htop display at this point:

0 [| 0.7%] Tasks: 37; 2 running
1 [|||||||||||||||||||||||||||||||||||||||||100.0%] Load average: 1.18 1.09 1.18
Mem[||||||||| 147M/1.90G] Time: 23:11:18
Swp[|| 76.8M/1.86G]
  PID START USER VIRT RES NI CPU% TIME+ S Command
 1310 22:42 g 366M 35076 0 88.0 38:14.58 R /usr/lib/xorg/Xorg -nolisten tcp :0 vt1 -keeptty -a
 4761 22:43 root 26844 4248 0 0.0 0:07.73 R htop
    1 08:36 root 219M 5388 0 0.0 0:04.58 S /sbin/init
 4922 23:04 root 27516 4688 0 1.3 0:01.89 S htop
 1371 22:42 g 30084 3112 0 0.0 0:01.20 S tmux new -d
 1316 22:42 g 48492 1596 0 0.0 0:00.68 S x-window-manager
 1490 22:42 g 0 0 0 0.0 0:00.50 Z xterm -bg black -fg white -rightbar -xrm *charClass
 4683 22:42 g 105M 4484 0 0.0 0:00.34 S sshd: g@pts/5
  257 22:42 root 78440 8432 0 0.0 0:00.27 S /lib/systemd/systemd-journald
  539 22:42 messagebu 50208 2084 0 0.0 0:00.13 S /usr/bin/dbus-daemon --system --address=systemd: --
 1372 22:42 root 61440 4136 0 0.0 0:00.12 S sudo -H -uG -s
 1338 22:42 g 50012 1312 0 0.0 0:00.11 S /usr/bin/dbus-daemon --syslog --fork --print-pid 5
 4684 22:42 g 29312 7552 0 0.0 0:00.10 S -bash
 1400 22:42 g 29324 2440 0 0.0 0:00.10 S -bash
 4850 23:04 g 61440 4180 0 0.0 0:00.10 S sudo -H -uG -s
 1251 22:42 g 29280 228 0 0.0 0:00.09 S -bash
 1971 22:42 g 29336 1040 0 0.0 0:00.09 S -bash
 4924 23:09 g 29312 7600 0 0.0 0:00.09 S -bash
 1347 22:42 g 0 0 0 0.0 0:00.08 Z /usr/bin/ssh-agent x-window-manager
 4727 22:43 root 28128 6480 0 0.0 0:00.06 S /bin/bash
 4887 23:04 root 28092 6472 0 0.0 0:00.06 S /bin/bash
  534 22:42 syslog 252M 1004 0 0.0 0:00.03 S /usr/sbin/rsyslogd -n
 4803 22:59 systemd-r 70592 5292 0 0.0 0:00.03 S /lib/systemd/systemd-resolved
 4814 22:59 systemd-t 138M 3200 0 0.0 0:00.03 S /lib/systemd/systemd-timesyncd
 4651 22:42 root 105M 7004 0 0.0 0:00.02 S sshd: g [priv]
 4779 22:54 root 45484 4024 0 0.0 0:00.02 S /lib/systemd/systemd-udevd
 4780 22:54 root 70564 6112 0 0.0 0:00.02 S /lib/systemd/systemd-logind
 4818 23:03 root 76688 3696 0 0.0 0:00.01 S /bin/login -p ---p -- \u --noclear tty1 linux
  681 22:42 root 25600 4 0 0.0 0:00.00 S /sbin/dhclient -1 -4 -v -pf /run/dhclient.eth0.pid
  712 22:42 root 72280 356 0 0.0 0:00.00 S /usr/sbin/sshd -D
 1287 22:42 g 4632 168 0 0.0 0:00.00 S /bin/sh /usr/bin/startx
 1309 22:42 g 22628 408 0 0.0 0:00.00 S xinit /etc/X11/xinit/xinitrc -- /etc/X11/xinit/xser
 1337 22:42 g 45688 72 0 0.0 0:00.00 S /usr/bin/dbus-launch --exit-with-session --sh-synta
 1519 22:42 g 82724 812 0 0.0 0:00.00 S /usr/lib/bluetooth/obexd
 2354 22:42 g 183M 368 0 0.0 0:00.00 S /usr/lib/dconf/dconf-service
 4723 22:42 g 21220 3556 0 0.0 0:00.00 S tmux set status 0; set visual-b on; set display-t 9
F1Help F2Setup F3SearchF4FilterF5Tree F6SortByF7Nice -F8Nice +F9Kill F10Quit

i resumed killing:

9: x-window-manager--Z
dbus-daemon --system --address=systemd: --nofork
dbus-daemon --syslog
sshd
dhclient
sshd -D
dbus-launch --exit-with-sess
dbus-daemon --nofork
(sd-pam)
xinit--
startx--
9: xinit

occasionally during the above batch of kills i checked whether ctl-alt-Fn might work yet, and they didn't, however at this point now they *do work* (xinit and startx both disappeared now tho xorg still present and consuming ~90% cpu). resuming kills:

xorg--
9: xorg

xorg finally gone now.

tried to re-launch xorg, failed.
tried apport-collect 1757299, failed, needed python3-launchpadlib.
installed python3-launchpadlib.
tried apport-collect 1757299, failed to launch a browser to authorize with launchpad.
left box running and grabbed some sleep and breakfast.
observed /var/crash contains only .lock with same date&time as /var/log/apport.log from last evening.
installed gpm, w3m, and links2.
apport-collect 1757299 succeeded.
submitted this comment.