attaching a docking station only work once, second time freezes

[Muelli]

I can reliably make Linux freeze.

If I boot past the cryptsetup password dialog into GDM (I think), attach a docking station, unattach, then reattach, the system freezes. At least I cannot move the mouse cursor anymore, switch VTs, reboot, num lock doesn't toggle.

I think it works well when *not* booting into GDM, but staying at the passphrase dialogue of the initramfs.

I'm having a Thinkpad X240 with two external monitors.

This is the standard ubuntu kernel, I haven't tested upstream kernels just yet. I'm intending to test with linux-image-4.6.0-040600-generic_4.6.0-040600.201605151930_amd64.deb from http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.6-yakkety/ now.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: linux-image-4.4.0-22-generic 4.4.0-22.40
ProcVersionSignature: Ubuntu 4.4.0-22.40-generic 4.4.8
Uname: Linux 4.4.0-22-generic x86_64
ApportVersion: 2.20.1-0ubuntu2
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: muelli 1991 F.... pulseaudio
 /dev/snd/controlC0: muelli 1991 F.... pulseaudio
CurrentDesktop: GNOME
Date: Wed May 18 10:35:15 2016
HibernationDevice: RESUME=UUID=af92c9d7-569e-41d4-86d2-af0ada5f9377
InstallationDate: Installed on 2015-12-02 (167 days ago)
InstallationMedia: Ubuntu-GNOME 16.04 LTS "Xenial Xerus" - Alpha amd64 (20151027)
MachineType: LENOVO 20AMS61707
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.4.0-22-generic root=/dev/mapper/lvm--vg-ubuntu--root ro rootflags=subvol=@ cryptopts=target=crypto,source=/dev/disk/by-uuid/4a1951b7-3604-4891-8ec6-3f5c9112d30d quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-4.4.0-22-generic N/A
 linux-backports-modules-4.4.0-22-generic N/A
 linux-firmware 1.157
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 03/10/2016
dmi.bios.vendor: LENOVO
dmi.bios.version: GIET85WW (2.35 )
dmi.board.asset.tag: Not Available
dmi.board.name: 20AMS61707
dmi.board.vendor: LENOVO
dmi.board.version: Not Defined
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnLENOVO:bvrGIET85WW(2.35):bd03/10/2016:svnLENOVO:pn20AMS61707:pvrThinkPadX240:rvnLENOVO:rn20AMS61707:rvrNotDefined:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 20AMS61707
dmi.product.version: ThinkPad X240
dmi.sys.vendor: LENOVO

[Muelli (ubuntu-bugs-auftrags-killer)]

the new kernel seems to work better indeed.
4.6.0-040600-generic #201605151930 SMP Sun May 15 23:32:59 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

[Brad Figg (brad-figg)]

This change was made by a bot.

[Joseph Salisbury (jsalisbury)]

We can perform a "Reverse" kernel bisect to find the commit that fixes this bug. We first need to find the last bad kernel version and first good one. Can you give v4.6-rc1 a test? It can be downloaded from:

http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.6-rc1-wily/

[Muelli (ubuntu-bugs-auftrags-killer)]

I first tested linux-image-4.6.0-040600rc1-generic_4.6.0-040600rc1.201603261930_amd64.deb and it *did* freeze.

I then tested linux-image-4.6.0-040600rc7-generic_4.6.0-040600rc7.201605081830_amd64.deb and it did not crash.

I then tested linux-image-4.6.0-040600rc4-generic_4.6.0-040600rc4.201604172330_amd64.deb and it did not crash.

I then tested linux-image-4.6.0-040600rc3-generic_4.6.0-040600rc3.201604120934_amd64.deb and it did not crash. However, when shutting down after my test, it oopsed and then did not shutdown, so I had to power off hard. I've captured the oops with my phone's cam if it's of any interest. Looked like a crash in the filesystem. Could have been a random btrfs crasher.

Then, I tested linux-image-4.6.0-040600rc2-generic_4.6.0-040600rc2.201604031130_amd64.deb and it *did* freeze after the first attempt to dock it to the station. I have not repeated the test though.

It felt as if the rc3 was also very slow when docking or undocking. It took a few seconds for the screen to blink, which happens every time my monitor configuration changes (i.e. after docking or undocking).

So the change happened somewhere between rc2 and rc3.
Note that my interest in building multiple kernels now is not very high.

[Claudio Pacchierotti (cpacchierotti)]

The same happens to me with an HP EliteBook and an HP UltraSlim docking station (using kernel 4.4.0-53-generic on Ubuntu 16.04).