System freezes when undocking laptop

[Luke Murray]

I have a Lenovo Thinkpad X260 docking with a Lenovo 40A20090UK docking station. I have two monitors plugged into the back of the dock via its two separate displayport connectors. Booting the machine whilst docked causes the machine to freeze when it is undocked. Same for booting undocked, then docking.

May relate to https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1604313

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: linux-image-4.4.0-34-generic 4.4.0-34.53
ProcVersionSignature: Ubuntu 4.4.0-34.53-generic 4.4.15
Uname: Linux 4.4.0-34-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/pcmC0D0p: luke 5384 F...m pulseaudio
 /dev/snd/controlC0: luke 5384 F.... pulseaudio
CurrentDesktop: i3
Date: Thu Aug 18 13:33:18 2016
EcryptfsInUse: Yes
HibernationDevice: RESUME=UUID=06d00448-ea78-46fb-8a32-6ec62b16a454
InstallationDate: Installed on 2016-06-06 (73 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
MachineType: LENOVO 20F6CTO1WW
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-34-generic.efi.signed root=UUID=6658071a-159f-4980-b5f8-a0b728bb8dc9 ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-4.4.0-34-generic N/A
 linux-backports-modules-4.4.0-34-generic N/A
 linux-firmware 1.157.3
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 06/01/2016
dmi.bios.vendor: LENOVO
dmi.bios.version: R02ET48W (1.21 )
dmi.board.asset.tag: Not Available
dmi.board.name: 20F6CTO1WW
dmi.board.vendor: LENOVO
dmi.board.version: SDK0J40697 WIN
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.modalias: dmi:bvnLENOVO:bvrR02ET48W(1.21):bd06/01/2016:svnLENOVO:pn20F6CTO1WW:pvrThinkPadX260:rvnLENOVO:rn20F6CTO1WW:rvrSDK0J40697WIN:cvnLENOVO:ct10:cvrNone:
dmi.product.name: 20F6CTO1WW
dmi.product.version: ThinkPad X260
dmi.sys.vendor: LENOVO

[Brad Figg (brad-figg)]

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 v4.8 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/v4.8-rc2/

[Luke Murray (luke-3)]

Upgrading to 4.8.0-rc2 kernel fixes this problem.

[penalvch (penalvch)]

Luke Murray, the next step is to fully reverse commit bisect from kernel 4.4 to 4.8-rc2 in order to identify the last bad commit, followed immediately by the first good one. Once this good commit has been identified, it may be reviewed for backporting. Could you please do this following https://wiki.ubuntu.com/Kernel/KernelBisection#How_do_I_reverse_bisect_the_upstream_kernel.3F ?

Please note, finding adjacent kernel versions is not fully commit bisecting.

Also, the kernel release names are irrelevant for the purposes of bisecting.

It is most helpful that after the fix commit (not kernel version) has been identified, you then mark this report Status Confirmed.

Thank you for your help.

[Launchpad Janitor (janitor)]

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]