System freeze with long strings of NUL characters (^@) in the logs

[Dario Bertero]

Experienced a system freeze. It was not possible to use the keyboard or the touchpad, it was possible to move the cursor using an USB mouse attached, but clicking had no effect. The strange thing is that at the time of the freeze /var/log/syslog and /var/log/kern.log displayed long strings of NUL bytes (^@).

---
ApportVersion: 2.19.1-0ubuntu2
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: brtdra 1818 F.... pulseaudio
 /dev/snd/controlC0: brtdra 1818 F.... pulseaudio
CurrentDesktop: Unity
DistroRelease: Ubuntu 15.10
HibernationDevice: RESUME=UUID=7c657863-dc0e-432f-9b9d-9bc4395cdf1c
InstallationDate: Installed on 2015-08-22 (57 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422)
MachineType: LENOVO 20CMCTO1WW
Package: linux (not installed)
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.2.0-16-generic.efi.signed root=UUID=da47e804-2239-47b1-a6d1-493ccca12588 ro noprompt persistent quiet splash vt.handoff=7
ProcVersionSignature: Ubuntu 4.2.0-16.19-generic 4.2.3
RelatedPackageVersions:
 linux-restricted-modules-4.2.0-16-generic N/A
 linux-backports-modules-4.2.0-16-generic N/A
 linux-firmware 1.149
Tags: wily
UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev'
Uname: Linux 4.2.0-16-generic x86_64
UpgradeStatus: Upgraded to wily on 2015-10-16 (2 days ago)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
_MarkForUpload: True
dmi.bios.date: 06/19/2015
dmi.bios.vendor: LENOVO
dmi.bios.version: N10ET36W (1.15 )
dmi.board.asset.tag: Not Available
dmi.board.name: 20CMCTO1WW
dmi.board.vendor: LENOVO
dmi.board.version: SDK0K11826 WIN
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.modalias: dmi:bvnLENOVO:bvrN10ET36W(1.15):bd06/19/2015:svnLENOVO:pn20CMCTO1WW:pvrThinkPadX250:rvnLENOVO:rn20CMCTO1WW:rvrSDK0K11826WIN:cvnLENOVO:ct10:cvrNone:
dmi.product.name: 20CMCTO1WW
dmi.product.version: ThinkPad X250
dmi.sys.vendor: LENOVO

[Brad Figg (brad-figg)]

This bug is missing log files that will aid in diagnosing the problem. From a terminal window please run:

apport-collect 1507338

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.

[Dario Bertero (anrvrx)]

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[Dario Bertero (anrvrx)]

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[Dario Bertero (anrvrx)]

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[Dario Bertero (anrvrx)]

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[Dario Bertero (anrvrx)]

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[Dario Bertero (anrvrx)]

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[Dario Bertero (anrvrx)]

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[Dario Bertero (anrvrx)]

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[Dario Bertero (anrvrx)]

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[Dario Bertero (anrvrx)]

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[Dario Bertero (anrvrx)]

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[Dario Bertero (anrvrx)]

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[Dario Bertero (anrvrx)]

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[Dario Bertero (anrvrx)]

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[Dario Bertero (anrvrx)]

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[penalvch (penalvch)]

Dario Bertero, thank you for reporting this and helping make Ubuntu better.

As per http://support.lenovo.com/us/en/products/laptops-and-netbooks/thinkpad-x-series-laptops/thinkpad-x250 an update to your computer's buggy and outdated BIOS is available (1.17). If you update to this following https://help.ubuntu.com/community/BIOSUpdate does it change anything?

If it doesn't, could you please both specify what happened, and provide the output of the following terminal command:
sudo dmidecode -s bios-version && sudo dmidecode -s bios-release-date

For more on BIOS updates and linux, please see https://help.ubuntu.com/community/ReportingBugs#Bug_reporting_etiquette .

Please note your current BIOS is already in the Bug Description, so posting this on the old BIOS would not be helpful. As well, you don't have to create a new bug report.

Once the BIOS is updated, if the problem is still reproducible, and the information above is provided, then please mark this report Status Confirmed. Otherwise, please mark this as Invalid.

Thank you for your understanding.

[Dario Bertero (anrvrx)]

I've just updated the bios:

N10ET38W (1.17 )
08/20/2015

I don't know if I will be able to reproduce the bug again. It happened suddenly while using some lightweight software (specifically Anki http://ankisrs.net/). As described above I could only move the cursor with the physical usb mouse, clicking, the touchpad and the keyboard were unresponsive. After turning off and on the machine and looking at the logs I foun that stange sequences of NUL characters.

[Launchpad Janitor (janitor)]

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