Unable to switch VTs - screen frozen. Even 'sudo chvt' hangs.

[Daniel van Vugt]

Prior to doing any Gnome Shell development I always disable the existing instance by dropping back to a non-graphical runlevel:

  sudo systemctl start multi-user.target

At least half the time this works. But the other half the time the screen freezes and I am not able to interact with it or switch VTs. Even a remote login can't force a VT switch:

  sudo chvt 4 # just hangs

The kernel log shows no errors at all.

ProblemType: Bug
DistroRelease: Ubuntu 18.10
Package: linux-image-4.15.0-22-generic 4.15.0-22.24
ProcVersionSignature: Ubuntu 4.15.0-22.24-generic 4.15.17
Uname: Linux 4.15.0-22-generic x86_64
ApportVersion: 2.20.10-0ubuntu3
Architecture: amd64
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/by-path', '/dev/snd/hwC0D2', '/dev/snd/hwC0D0', '/dev/snd/pcmC0D9p', '/dev/snd/pcmC0D8p', '/dev/snd/pcmC0D7p', '/dev/snd/pcmC0D3p', '/dev/snd/pcmC0D2c', '/dev/snd/pcmC0D0c', '/dev/snd/pcmC0D0p', '/dev/snd/controlC0', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
Date: Fri Jun 8 13:21:38 2018
InstallationDate: Installed on 2018-05-26 (12 days ago)
InstallationMedia: Ubuntu 18.10 "Cosmic Cuttlefish" - Alpha amd64 (20180525)
Lsusb:
 Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 001 Device 004: ID 17ef:6009 Lenovo ThinkPad Keyboard with TrackPoint
 Bus 001 Device 003: ID 045e:0047 Microsoft Corp. IntelliMouse Explorer 3.0
 Bus 001 Device 002: ID 8087:0a2b Intel Corp.
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: LENOVO 10M7CTO1WW
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_AU.UTF-8
 SHELL=/bin/bash
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-22-generic root=UUID=d7ecc709-02c2-4413-b7e7-dfce1d2b3703 ro quiet splash vt.handoff=1
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon.
RelatedPackageVersions:
 linux-restricted-modules-4.15.0-22-generic N/A
 linux-backports-modules-4.15.0-22-generic N/A
 linux-firmware 1.174
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 02/06/2018
dmi.bios.vendor: LENOVO
dmi.bios.version: M16KT47A
dmi.board.name: 3102
dmi.board.vendor: LENOVO
dmi.board.version: SDK0J40709 WIN 3259627060530
dmi.chassis.type: 3
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.modalias: dmi:bvnLENOVO:bvrM16KT47A:bd02/06/2018:svnLENOVO:pn10M7CTO1WW:pvrThinkCentreM710s:rvnLENOVO:rn3102:rvrSDK0J40709WIN3259627060530:cvnLENOVO:ct3:cvrNone:
dmi.product.family: ThinkCentre M710s
dmi.product.name: 10M7CTO1WW
dmi.product.version: ThinkCentre M710s
dmi.sys.vendor: LENOVO

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This change was made by a bot.

[Joseph Salisbury (jsalisbury)]

Did this issue start happening after an update/upgrade? Was there a prior kernel version where you were not having this particular problem?

Would it be possible for you to test the latest upstream kernel? Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Please test the latest v4.17 kernel[0].

If this bug is fixed in the mainline kernel, please add the following tag 'kernel-fixed-upstream'.

If the mainline kernel does not fix this bug, please add the tag: 'kernel-bug-exists-upstream'.

Once testing of the upstream kernel is complete, please mark this bug as "Confirmed".

Thanks in advance.

[0] http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.17

[Daniel van Vugt (vanvugt)]

This bug has existed for as long as I remember. I do not know of any kernel version that didn't have it, but at the same time I have only been trying for a year or less.

[Daniel van Vugt (vanvugt)]

Yes the bug still exists in: http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.17.1/

[Daniel van Vugt (vanvugt)]

Possibly related to (causing) bug 1773875