GDM3 display manager: logon constantly trying to "press enter" - unable to login using PTY

[fermulator]

I've seen this on Fedora (GDM+gnome-shell) in the past (can't remember how I fixed it, or if it just went away one day with an OS upgrade). Recently upgraded from Ubuntu 16.04.4 to 17.04, and this issue is present here now as well.

My setup:
 * dual monitors
 * multiple local users
 * often 2x users logged in at same time
 * flip between them using PTY (CTRL+ALT+ F2, F3, etc.)
 * CTRL+ALT+F1 gets us to the gdm login screen (user selection)

What happens:
 * eventually either by timeout (or after suspend), or manual lock screen
 * user hits CTRL+ALT+F2,3,X, to access their PTY
 * screen is locked
 * login screen is presented with user, password entry and cancel/unlock
 * the screen is _already_ saying "Authentication Failed" over and over and over (orange text)
 * if the user tries to enter their password, it "cuts them off" too fast, and they can't even complete entry! - my password is in fact so long >16chars, it's seemingly not humanly possible to enter it within the short ~500ms window between resets...

Reproducibility:
 * uncertain exactly how/when it starts
 * after multiple PTY switches maybe
 * perhaps related to sending the system into sleep S3 and resuming
 * sometimes I use the proper gnome-shell "switch user" functionality

Issue Analysis:
 * none - need guidance on how to debug/isolate next time it happens

---

System Information:

$ lsb_release -rd
Description: Ubuntu 17.04
Release: 17.04

$ uname -a
Linux fermmy 4.10.0-42-generic #46-Ubuntu SMP Mon Dec 4 14:38:01 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

$ apt-cache policy gdm3
gdm3:
  Installed: 3.24.1-0ubuntu0.2
  Candidate: 3.24.1-0ubuntu0.2
  Version table:
 *** 3.24.1-0ubuntu0.2 500
        500 http://ca.archive.ubuntu.com/ubuntu zesty-updates/universe amd64 Packages
        500 http://security.ubuntu.com/ubuntu zesty-security/universe amd64 Packages
        100 /var/lib/dpkg/status
     3.24.0-0ubuntu2 500
        500 http://ca.archive.ubuntu.com/ubuntu zesty/universe amd64 Packages

$ apt-cache policy gnome-shell
gnome-shell:
  Installed: 3.24.2-0ubuntu0.1
  Candidate: 3.24.2-0ubuntu0.1
  Version table:
 *** 3.24.2-0ubuntu0.1 500
        500 http://ca.archive.ubuntu.com/ubuntu zesty-updates/universe amd64 Packages
        100 /var/lib/dpkg/status
     3.24.0-0ubuntu2 500
        500 http://ca.archive.ubuntu.com/ubuntu zesty/universe amd64 Packages

ProblemType: Bug
DistroRelease: Ubuntu 17.04
Package: gdm3 3.24.1-0ubuntu0.2
ProcVersionSignature: Ubuntu 4.10.0-42.46-generic 4.10.17
Uname: Linux 4.10.0-42-generic x86_64
ApportVersion: 2.20.4-0ubuntu4.10
Architecture: amd64
CurrentDesktop: GNOME
Date: Fri Jan 5 12:24:06 2018
EcryptfsInUse: Yes
InstallationDate: Installed on 2013-05-11 (1700 days ago)
InstallationMedia: Ubuntu 12.04.2 LTS "Precise Pangolin" - Release amd64 (20130213)
SourcePackage: gdm3
UpgradeStatus: Upgraded to zesty on 2017-12-30 (6 days ago)
mtime.conffile..etc.gdm3.custom.conf: 2018-01-02T23:13:17.149142

[Daniel van Vugt (vanvugt)]

It sounds like you might have a key repeating, only logically in software, and only in gdm3.

You may wish to:
  (a) Test a different keyboard, even briefly; or
  (b) When the problem happens again, on the login screen tap your Enter, Shift, Ctrl, Alt keys a few times each. If one is virtually stuck down in software that might unstick it.

[fermulator (fermulator)]

If it were a physical key stuck issue, the login screen would be attempting login much faster (there is a key repeat frequency for held down keys).

I did confirm by "smushing" the keys.

Also, if the user goes to a non-graphical PTY terminal, there are NO symptoms of "stuck keys".

So it's definitely not a hardware/keyboard problem.

--
However, as suggested, it _could_ be a soft-issue within GDM3. Next time the situation occurs, is there any other debug information to gather other than "try to tap some keys"?

[fermulator (fermulator)]

Ha; selected LOCK SCREEN just now, and rolled up the GDM login, boom reproduced.

SUSPECT:
, in order to reproduce https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/1739525, at the start of ever session, I've been restarting gnome-shell through gpb with:
```
gdb --args gnome-shell --replace
```

This could be relevant here.

[dino99 (9d9)]

That version is now dead
http://news.softpedia.com/news/ubuntu-17-04-zesty-zapus-has-reached-end-of-life-upgrade-to-ubuntu-17-10-now-519360.shtml

[Daniel van Vugt (vanvugt)]

I would have said this:
---

Thank you for reporting this bug to Ubuntu.
Ubuntu 17.04 (zesty) reached end-of-life on January 13, 2018.

See this document for currently supported Ubuntu releases:
https://wiki.ubuntu.com/Releases

We appreciate that this bug may be old and you might not be interested in discussing it any more. But if you are then please upgrade to the latest Ubuntu version and re-test.

[fermulator (fermulator)]

fun

[fermulator (fermulator)]

over the next few days/weeks, since upgrading to Ubuntu 17.10 (gnome-shell 3.26.2), will monitor for this issue to reproduce

[fermulator (fermulator)]

Reporting back, not experiencing the bug anymore.
How can this be closed as "obsolete"?

[dino99 (9d9)]

Well, you was the only one affected by that problem (so a local issue i would say); and you now confirm 17.10 is not reproducing the bug; that's a good news, and enough to close it.