Hang at screen unlock (gdm / 18.04)

[Christian Ehrhardt ]

For two days in a row (one would have been a one-off WTF that I don't care to report) my system now hang after unlocking from the UI.

I can't see any obvious hanging processes that would be the obvious reason.

OVer day I have a few screen locks e.g. when going for lunch, but at least 2/2 times it only appeared when the lock was active over night. I'm not sure it if it the duration or that some job kicks in at night.

I have used apport to collect the basics, and will add some more debug data.

If you find a lead in there let me know, otherwise assuming I might face this every morning please let me know what to check next time it happens so that we can find the root cause.

I found similar bug 1285258 - but other than there I can NOT hit cancel to get a second chance, nothing in the UI moves at all and all I can do is drop to a non UI console with CTRL+ALT+F3 and debug from there.

I found that restarting gdm (systemctl restart gdm) gets me logged in, therefore I'll also attach a journal log so that you can look for issues in there.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: gdm3 3.28.3-0ubuntu18.04.3
ProcVersionSignature: Ubuntu 4.18.0-13.14~18.04.1-generic 4.18.17
Uname: Linux 4.18.0-13-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.9-0ubuntu7.5
Architecture: amd64
Date: Fri Jan 25 06:59:10 2019
InstallationDate: Installed on 2018-10-12 (104 days ago)
InstallationMedia: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
SourcePackage: gdm3
UpgradeStatus: No upgrade log present (probably fresh install)

[Daniel van Vugt (vanvugt)]

There'a a lot of log data in comment #4 and a few possible problems:

1. The kernel is crashing repeatedly in wifi-related code:

Jan 10 16:17:19 Keschdeichel kernel: wlp4s0: Failed check-sdata-in-driver check, flags: 0x0

   Please try downgrading to the official bionic kernel (v4.15) and/or avoid using wifi for a while.

2. There are some errors from unsupported gnome-shell extensions. Please uninstall extensions such as '<email address hidden>'. Disabling them isn't enough.

3. It looks like you ran out of disk space at one point. Please check that.

4. Near the end (the hang) a couple of components mention I/O errors:

Jan 25 07:08:30 Keschdeichel gsd-power[4979]: Error setting property 'PowerSaveMode' on interface org.gnome.Mutter.DisplayConfig: Timeout was reached (g-io-error-quark, 24)

Jan 25 07:09:33 Keschdeichel gvfsd[4865]: Error 2: Error 02ff: PTP I/O Error

   which may indicate a disk is starting to fail. Or it may be unrelated to disks completely.

5. Near the end (the hang) your CPU started to overheat:

Jan 25 07:09:36 Keschdeichel kernel: CPU2: Core temperature above threshold, cpu clock throttled (total events = 3993)
Jan 25 07:09:36 Keschdeichel kernel: CPU6: Core temperature above threshold, cpu clock throttled (total events = 3993)
Jan 25 07:09:36 Keschdeichel kernel: CPU2: Package temperature above threshold, cpu clock throttled (total events = 13593)
Jan 25 07:09:36 Keschdeichel kernel: CPU6: Package temperature above threshold, cpu clock throttled (total events = 13593)
Jan 25 07:09:36 Keschdeichel kernel: CPU4: Package temperature above threshold, cpu clock throttled (total events = 13593)
Jan 25 07:09:36 Keschdeichel kernel: CPU0: Package temperature above threshold, cpu clock throttled (total events = 13593)
Jan 25 07:09:36 Keschdeichel kernel: CPU1: Package temperature above threshold, cpu clock throttled (total events = 13592)
Jan 25 07:09:36 Keschdeichel kernel: CPU5: Package temperature above threshold, cpu clock throttled (total events = 13593)
Jan 25 07:09:36 Keschdeichel kernel: CPU7: Package temperature above threshold, cpu clock throttled (total events = 13593)
Jan 25 07:09:36 Keschdeichel kernel: CPU3: Package temperature above threshold, cpu clock throttled (total events = 13593)

Please also follow these instructions to check for possible crashes:

https://wiki.ubuntu.com/Bugs/Responses#Missing_a_crash_report_or_having_a_.crash_attachment

[Daniel van Vugt (vanvugt)]

Unassigning gdm3 since it is unchanged since October.

[Daniel van Vugt (vanvugt)]

Given the CPU started to overheat you might want to log in remotely via SSH from another machine and leave 'top' running. Then next time the problem occurs tell us what is using all the CPU according to 'top'.

[Christian Ehrhardt  (paelzer)]

Hi Daniel, thanks for taking a look.

#1 the WIFI crash is known (bug 1804841) and much worse with the 4.15 kernel
I'm not actively using WIFI atm due to that, it is just NM trying to configure it as fallback.
But all networking goes via Wire

#3 I handled, that was a while before the issues and the last cycle of "reboot -> hang" did not have a out of space issue

#4 no kernel nor smart on the disk have any I/O errors.
For now I'd think this is a GVFS thing but no real disk issue.

#5 the heat issue is common whenever I run all-core builds or if I use hangout/meets
I usually replace the thermal conductor after a year then this is better, but this laptop is just 3 months old - so not doing that yet (want to keep my Guarantees).

IMHO That leaves #2 the shell extensions as potential source of errors.
I more recently installed two that I now removed.
- gnome-shell-extension-multi-monitors
- gnome-shell-extension-system-monitor
Lets see if it is any better with that.

The next to remove would be (listing those active, but I'd remove the pkg reading from you that disabling isn't enough):
- alternate-tab (pkg: gnome-shell-extensions)
- ubuntu-appindicators (pkg: gnome-shell-extensions)
- workspace indicator (pkg: gnome-shell-extensions)
- ubuntu-appindicator (pkg: gnome-shell-extension-appindicator)

I can't really remove the latter as ubuntu-desktop depends on it

Finally I'll only remove package 'gnome-shell-extension-dash-to-panel' when this is my last hope as I really hate dash and love it when it is all on the panel (KDE style).
But I will certainly give it a try if the issue continues to bug me.

Ok, consider this incomplete for now.
My steps are:
1. run without gnome-shell-extension-multi-monitors gnome-shell-extension-system-monitor
2. run without gnome-shell-extensions
3. run without gnome-shell-extension-dash-to-panel

I'll be reporting back here, but since each of those tests will need at least a day that will be a while.

Thank you so much Daniel for giving me at least a list of things to try - feels better already!

[Christian Ehrhardt  (paelzer)]

Since removing
- gnome-shell-extension-multi-monitors
- gnome-shell-extension-system-monitor
The issue is no more triggering.

Thanks as it resolved my issue.
I'm not sure if we can do much more, lets keep it incomplete

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.