Thunderbolt3 dock freezes X on hotplug when used with external displays

[Dmitry Misharov]

This bug is very similar to https://bugs.launchpad.net/dell-sputnik/+bug/1752165 and has the same steps to reproduce, but it's not related to nvidia drivers. I have Lenovo Thinkpad T480s connected to a ThinkPad Thunderbolt 3 Dock. I have installed 4.15.0.46, 4.18.0.16 kernel. Both of these kernels have the issue. I followed this comment https://bugs.launchpad.net/dell-sputnik/+bug/1752165/comments/41 and installed 4.20.6 from UKUU and the issue is gone.
---
ProblemType: Bug
ApportVersion: 2.20.9-0ubuntu7.6
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: dmisharo 2223 F.... pulseaudio
 /dev/snd/pcmC0D0p: dmisharo 2223 F...m pulseaudio
 /dev/snd/controlC1: dmisharo 2223 F.... pulseaudio
CurrentDesktop: KDE
DistroRelease: KDE neon 18.04
HibernationDevice: RESUME=UUID=611a9c7d-fcaa-4717-b1d2-d89edca7e661
InstallationDate: Installed on 2018-11-25 (114 days ago)
InstallationMedia: neon user "Bionic" - Build amd64 LIVE Binary 20181122-05:40
MachineType: LENOVO 20L8S2N80E
Package: linux (not installed)
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.18.0-16-generic root=/dev/mapper/neon--vg-root ro quiet splash vt.handoff=1
ProcVersionSignature: Ubuntu 4.18.0-16.17~18.04.1-generic 4.18.20
RelatedPackageVersions:
 linux-restricted-modules-4.18.0-16-generic N/A
 linux-backports-modules-4.18.0-16-generic N/A
 linux-firmware 1.173.3
Tags: bionic
Uname: Linux 4.18.0-16-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip docker lpadmin plugdev sambashare sudo
_MarkForUpload: True
dmi.bios.date: 07/18/2018
dmi.bios.vendor: LENOVO
dmi.bios.version: N22ET48W (1.25 )
dmi.board.asset.tag: Not Available
dmi.board.name: 20L8S2N80E
dmi.board.vendor: LENOVO
dmi.board.version: Not Defined
dmi.chassis.asset.tag: RH0023049
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.modalias: dmi:bvnLENOVO:bvrN22ET48W(1.25):bd07/18/2018:svnLENOVO:pn20L8S2N80E:pvrThinkPadT480s:rvnLENOVO:rn20L8S2N80E:rvrNotDefined:cvnLENOVO:ct10:cvrNone:
dmi.product.family: ThinkPad T480s
dmi.product.name: 20L8S2N80E
dmi.product.sku: LENOVO_MT_20L8_BU_Think_FM_ThinkPad T480s
dmi.product.version: ThinkPad T480s
dmi.sys.vendor: LENOVO

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

This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:

apport-collect 1820811

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Dmitry Misharov (quarckster)]

apport information

[Dmitry Misharov (quarckster)]

apport information

[Dmitry Misharov (quarckster)]

apport information

[Dmitry Misharov (quarckster)]

apport information

[Dmitry Misharov (quarckster)]

apport information

[Dmitry Misharov (quarckster)]

apport information

[Dmitry Misharov (quarckster)]

apport information

[Dmitry Misharov (quarckster)]

apport information

[Dmitry Misharov (quarckster)]

apport information

[Dmitry Misharov (quarckster)]

apport information

[Dmitry Misharov (quarckster)]

apport information

[Dmitry Misharov (quarckster)]

apport information

[Dmitry Misharov (quarckster)]

apport information

[Dmitry Misharov (quarckster)]

apport information

[Dmitry Misharov (quarckster)]

apport information

[Kai-Heng Feng (kaihengfeng)]

Would it be possible for you to do a kernel bisection?

First, find the first good -rc kernel and the last bad -rc kernel from http://kernel.ubuntu.com/~kernel-ppa/mainline/

Then,
$ sudo apt build-dep linux
$ git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
$ cd linux
$ git bisect start
$ git bisect new $(the good version you found)
$ git bisect old $(the bad version found)
$ make localmodconfig
$ make -j`nproc` deb-pkg
Install the newly built kernel, then reboot with it.
If the issue still happens,
$ git bisect old
Otherwise,
$ git bisect new
Repeat to "make -j`nproc` deb-pkg" until you find the commit that contains the fix.

[Bernie Bernstein (bernie9998)]

We are trying to determine if this bug is related to bug #1819924.

With the affected kernel versions, does the hang still occur if the dock is connected before booting?

That is, with your computer shut off, plug in the dock and then boot up. Does the computer hang after booting?

If not, are you then able to hot-plug (disconnect and re-connect) without issue?

[Dmitry Misharov (quarckster)]

> With the affected kernel versions, does the hang still occur if the dock is connected before booting?

No, the hang only occurs when I plug the cable to my laptop in running OS.

> That is, with your computer shut off, plug in the dock and then boot up. Does the computer hang after booting?

No, OS boots up fine with plugged cable.

[Bernie Bernstein (bernie9998)]

Sorry for the delayed followup, but if your machine is booted with it plugged in, are you then able to unplug and re-plug the device without issue?

Or does the hang re-occur regardless of whether the device was plugged in at boot or not?

[Dmitry Misharov (quarckster)]

Yes, hang re-occurs regardless of whether the device was plugged in at boot or not.

[Dmitry Misharov (quarckster)]

It seems 4.18.0-18 fixes the issue.