Kernel Configuration File System

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upnort
Posts: 62
Joined: 2014/10/21 20:37:57

Kernel Configuration File System

Post by upnort » 2018/12/09 18:23:30

I updated some CentOS 7 systems to 7.6-1810. Normal yum update.

I have seen some systems stall on shutdown/reboot but inconsistently. The cause seems to be related to unmounting file systems, such as tmpfs.

One such related message:

Failed to unmount Kernel Configuration File System

The related service file is /usr/lib/systemd/system/sys-kernel-config.mount. The file is installed from the systemd package.

No related messages on boot.

The /sys/kernel/config directory exists but is empty.

There is no such failure message on systems not updated to 7.6-1810. Same failure on bare metal or virtual.

I searched the web and found no related discussions or problem reports. I see nothing in the logs but that might be me.

This specific failure does not cause any stalls and seems to be a nuisance only. Nonetheless I would like to see a clean shutdown/reboot.

Any ideas how to fix?

Thanks much. :)

upnort
Posts: 62
Joined: 2014/10/21 20:37:57

Re: Kernel Configuration File System

Post by upnort » 2018/12/16 21:31:46

No replies? :(

dunch
Posts: 66
Joined: 2018/11/07 13:48:53
Location: Yorkshire

Re: Kernel Configuration File System

Post by dunch » 2018/12/19 09:37:53

Code: Select all

# mount securityfs /sys/kernel/security/ -t securityfs -o rw,nosuid,nodev,noexec,relatime

upnort
Posts: 62
Joined: 2014/10/21 20:37:57

Re: Kernel Configuration File System

Post by upnort » 2018/12/20 19:10:45

Thank you for the reply. The file system is already mounted at boot. The error message appears during shutdown/reboot.

Masking the service has no effect on booting -- the service still mounts the system. Stopping the service (systemctl stop sys-kernel-config.mount) has no effect and results in the same error message.

If I run 'umount configfs' or 'umount /sys/kernel/config' before rebooting, then there is no error message.

I looked at the configfs.txt, but saw nothing obvious.

Edit: Looks the real failure is this:

Failed at step CGROUP spawning /bin/umount: No such file or directory
Process /bin/umount could not be executed

Similar to this bug report.

/bin/umount does exist with perms root:root 2755.

upnort
Posts: 62
Joined: 2014/10/21 20:37:57

Re: Kernel Configuration File System

Post by upnort » 2018/12/22 05:39:24

After many hours of digging, the error message listed in the original post is caused by not having NetworkManager installed and more specifically, not enabling NetworkManager.

Our servers all use static IP addresses. NM never has been needed or wanted.

I am unable to find a way to disable or remove NM without triggering the original error. I have found no way to disable sys-kernel-config.mount.

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