To simplify reproduce steps, one only has to:
1. install (tested so far) Ubuntu Bionic
2. switch to other tty by pressing Ctrl+Alt+Fn
3. login and logout
Then it should try to switch back to GDM (no matter you have logged in GUI or not), triggers vt-switch bug and lock up.
Some more findings:
1. So far we know all other newer Ubuntu versions are immune, e.g. Ubuntu Cosmic's gdm(version 3.30.1-1ubuntu5).
2. login _and_ logout from another virtual console is required. Switching between text console and GUI back and forth before logging out doesn't trigger this bug. So this might(?) also involves systemd-logind as well;
3. while gdm locked up, kernel and the rest of the system are actually still alive. Networking is still available, and even the input devices are still functioning well. Only gdm fails to grab the device inputs.
4. when gdm locks up due to either resume from suspend or vt-switch, restart gdm (from remote ssh) will bring the system back.
### Disco
| |4.15|4.18|4.19|5.0
|---|----|----|----|---
|nouveau| | | |
|nvidia-390 bionic|Affected|Affected|Affected|Affected
|nvidia-390 cosmic|Affected|Affected|Affected|Affected
|nvidia-410|Affected|Affected|Affected|Affected
Affected: only gdm(vt-1) fails to grab further input. Use `chvt` to switch to other vt in a remote shell.
#### Packages:
* kernel:
* 4.15.0-46-generic
* 4.18.0-16-generic
* 4.19.0-13-generic
* 5.0.0-7-generic
* nvidia-driver:
* 390.116-0ubuntu0.18.04.1
* 390.116-0ubuntu0.18.10.1
* 410.104-0ubuntu1
* systemd:
* 240-6ubuntu1
* gdm3:
* 3.31.4+git20190225-1ubuntu1
#### Hardware
* 201811-26623
Summary: in Ubuntu Disco, nouveau driver is immune from this issue in all kernel versions tested. In contrary, nVIDIA driver fails every case.
### Cosmic
| |4.15|4.18|4.19|5.0
|-----------------|----|----|----|---
|nouveau | | | |
|nvidia-390 bionic|Affected|Affected|Affected|Affected
|nvidia-390 cosmic|Affected|Affected|Affected|Affected
|nvidia-410 |Affected|Affected|Affected|Affected
Affected: only gdm(vt-1) fails to grab further input. Use `chvt` to switch to other vt in a remote shell.
#### Packages:
* kernel:
* 4.15.0-46-generic
* 4.18.0-16-generic
* 4.19.0-13-generic
* 5.0.0-7-generic
* nvidia-driver:
* 390.116-0ubuntu0.18.04.1
* 390.116-0ubuntu0.18.10.1
* 410.104-0ubuntu1
* systemd:
* 239-7ubuntu10
* gdm3:
* 3.30.1-1ubuntu5
#### Hardware
* 201811-26623
Summary: in Ubuntu Cosmic, same with Disco.
# Bionic
| |4.15|4.18 |4.19
|-----------------|----|------------|----
|nouveau|Affected[1]| |Affected[1]
|hwe xorg|Affected[1]| |Affected[1]
|nvidia-390 bionic+hwe xorg|Affected[1]|Affected[1]|Affected[1]
|nvidia-390 bionic|Affected[2]|Affected[1]|Affected[1]
|nvidia-390 cosmic|Affected[1]|Affected[1]|Affected[1]
|nvidia-410 |Affected[2]|Affected[1]|Affected[3]
[1]: no vt-switch inside gnome-shell. Press Ctrl+Alt+Fn in gdm instead. Only gdm(vt-1) fails to grab further input. Use `chvt` to switch to other vt in a remote shell.
[2]: vt-switch inside gnome-shell causes lockup. Cannot switch to vt in gdm (but no system lockup). Only gdm(vt-1) fails to grab further input. Use `chvt` to switch to other vt in a remote shell.
[3]: vt-switch inside gnome-shell causes lockup. Press Ctrl+Alt+Fn in gdm instead. Only gdm(vt-1) fails to grab further input. Use `chvt` to switch to other vt in a remote shell.
## Packages:
* kernel:
* 4.15.0-46-generic
* 4.18.0-16-generic
* 4.19.0-13-generic
* nvidia-driver:
* 390.116-0ubuntu0.18.04.1
* 390.116-0ubuntu0.18.10.1
* 410.104-0ubuntu1
* systemd:
* 237-3ubuntu10.12
* gdm3:
* 3.28.3-0ubuntu18.04.3
## Hardware
* 201811-26623
Summary: only 4.18 kernel with nouveau driver is immune from this issue, which follows some changes in user land should be necessary to stabilize all the (nouveau) cases. But even with that, from previous results of Cosmic/Disco, there should still some works to be done in the nvidia driver.
OEM-tag: LP: #1804607
If you can still ssh in while the screen is frozen then please do so and run:
dmesg > frozendmesg.txt
and send us the file 'frozendmesg.txt'