Stuck attempting to acess "/proc/sys/kernel/nmi_watchdog" file

[Andrey Gelman]

I has always been able to both read and write "/proc/sys/kernel/nmi_watchdog" file.
After the recent kernel update (4.4.0-108-generic, updated on 10-Jan-2018) the computer merely gets stuck on these commands. Ctrl-C cannot interrupt.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: linux-image-4.4.0-108-generic 4.4.0-108.131
ProcVersionSignature: Ubuntu 4.4.0-108.131-generic 4.4.98
Uname: Linux 4.4.0-108-generic x86_64
AlsaVersion: Advanced Linux Sound Architecture Driver Version k4.4.0-108-generic.
AplayDevices: Error: [Errno 2] No such file or directory: 'aplay'
ApportVersion: 2.20.1-0ubuntu2.15
Architecture: amd64
ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord'
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/by-path', '/dev/snd/hwC0D2', '/dev/snd/hwC0D0', '/dev/snd/pcmC0D7p', '/dev/snd/pcmC0D3p', '/dev/snd/pcmC0D2c', '/dev/snd/pcmC0D1p', '/dev/snd/pcmC0D0c', '/dev/snd/pcmC0D0p', '/dev/snd/controlC0', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
Card0.Amixer.info: Error: [Errno 2] No such file or directory: 'amixer'
Card0.Amixer.values: Error: [Errno 2] No such file or directory: 'amixer'
Date: Wed Jan 10 12:30:37 2018
HibernationDevice: RESUME=UUID=a0f49bd7-5ec0-414e-8183-41221652c849
InstallationDate: Installed on 2016-08-17 (510 days ago)
InstallationMedia: Ubuntu-Server 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig'
Lsusb:
 Bus 001 Device 003: ID 04b4:6570 Cypress Semiconductor Corp.
 Bus 001 Device 002: ID 8087:07e6 Intel Corp.
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: CompuLab Ltd. SBC-iBT
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-108-generic.efi.signed root=UUID=1ee7c5d5-a843-43d4-a90d-0c484d09d041 ro
RelatedPackageVersions:
 linux-restricted-modules-4.4.0-108-generic N/A
 linux-backports-modules-4.4.0-108-generic N/A
 linux-firmware 1.157.14
RfKill: Error: [Errno 2] No such file or directory: 'rfkill'
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 02/24/2015
dmi.bios.vendor: CompuLab Ltd.
dmi.bios.version: SBC-iBT_3.1.0.314 X64
dmi.board.asset.tag: None
dmi.board.name: SBC-iBT
dmi.board.vendor: CompuLab Ltd.
dmi.board.version: 1.x
dmi.chassis.asset.tag: Asset Tag
dmi.chassis.type: 11
dmi.chassis.vendor: CompuLab Ltd.
dmi.chassis.version: 1.0
dmi.modalias: dmi:bvnCompuLabLtd.:bvrSBC-iBT_3.1.0.314X64:bd02/24/2015:svnCompuLabLtd.:pnSBC-iBT:pvr1.x:rvnCompuLabLtd.:rnSBC-iBT:rvr1.x:cvnCompuLabLtd.:ct11:cvr1.0:
dmi.product.name: SBC-iBT
dmi.product.version: 1.x
dmi.sys.vendor: CompuLab Ltd.

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

This change was made by a bot.

[Joseph Salisbury (jsalisbury)]

This may be a duplicate of bug 1741934, which was fixed by the 4.4.0-109 kernel. Can you upgrade to 4.4.0-109 and see if this bug still exists?

[Andrey Gelman (andrey-gelman)]

Hi !
Indeed this fixes the issue:
--
# cat /proc/sys/kernel/nmi_watchdog
0
--
Thank you !
Andrey Gelman

On Wed, Jan 10, 2018 at 11:15 PM, Joseph Salisbury <
<email address hidden>> wrote:

> This may be a duplicate of bug 1741934, which was fixed by the 4.4.0-109
> kernel. Can you upgrade to 4.4.0-109 and see if this bug still exists?
>
> ** Changed in: linux (Ubuntu)
> Importance: Undecided => Medium
>
> ** Changed in: linux (Ubuntu)
> Status: Confirmed => Incomplete
>
> ** Tags added: pti
>
> ** Changed in: linux (Ubuntu)
> Assignee: (unassigned) => Joseph Salisbury (jsalisbury)
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1742418
>
> Title:
> Stuck attempting to acess "/proc/sys/kernel/nmi_watchdog" file
>
> Status in linux package in Ubuntu:
> Incomplete
>
> Bug description:
> I has always been able to both read and write "/proc/sys/kernel/nmi_watchdog"
> file.
> After the recent kernel update (4.4.0-108-generic, updated on
> 10-Jan-2018) the computer merely gets stuck on these commands. Ctrl-C
> cannot interrupt.
>
> ProblemType: Bug
> DistroRelease: Ubuntu 16.04
> Package: linux-image-4.4.0-108-generic 4.4.0-108.131
> ProcVersionSignature: Ubuntu 4.4.0-108.131-generic 4.4.98
> Uname: Linux 4.4.0-108-generic x86_64
> AlsaVersion: Advanced Linux Sound Architecture Driver Version
> k4.4.0-108-generic.
> AplayDevices: Error: [Errno 2] No such file or directory: 'aplay'
> ApportVersion: 2.20.1-0ubuntu2.15
> Architecture: amd64
> ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord'
> AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/by-path',
> '/dev/snd/hwC0D2', '/dev/snd/hwC0D0', '/dev/snd/pcmC0D7p',
> '/dev/snd/pcmC0D3p', '/dev/snd/pcmC0D2c', '/dev/snd/pcmC0D1p',
> '/dev/snd/pcmC0D0c', '/dev/snd/pcmC0D0p', '/dev/snd/controlC0',
> '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
> Card0.Amixer.info: Error: [Errno 2] No such file or directory: 'amixer'
> Card0.Amixer.values: Error: [Errno 2] No such file or directory: 'amixer'
> Date: Wed Jan 10 12:30:37 2018
> HibernationDevice: RESUME=UUID=a0f49bd7-5ec0-414e-8183-41221652c849
> InstallationDate: Installed on 2016-08-17 (510 days ago)
> InstallationMedia: Ubuntu-Server 16.04.1 LTS "Xenial Xerus" - Release
> amd64 (20160719)
> IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig'
> Lsusb:
> Bus 001 Device 003: ID 04b4:6570 Cypress Semiconductor Corp.
> Bus 001 Device 002: ID 8087:07e6 Intel Corp.
> Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
> MachineType: CompuLab Ltd. SBC-iBT
> ProcFB: 0 inteldrmfb
> ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-108-generic.efi.signed
> root=UUID=1ee7c5d5-a843-43d4-a90d-0c484d09d041 ro
> RelatedPackageVersions:
> linux-restricted-modules-4.4.0-108-generic N/A
> linux-backports-modules-4.4.0-108-generic N/A
> linux-firmware 1.157.14
> RfKill: Error: [Errno 2] No such file or directory: 'rfkill'
> SourcePackage: linux
> UpgradeStatus: No upgrade log present (probably fresh instal...