ERROR: can't open file '/sys/fs/cgroup/cpu/gpdb/6438/cgroup.procs': No such file or directory (resgroup-ops-linux.c:909)

Products

• VMware Tanzu Greenplum

Issue/Introduction

The cgroups filesystem has been unmounted.

Resolution

To mount cgroups back without rebooting the system:

• Identify the cgroup version:

There are two main cgroup versions: cgroup v1 and cgroup v2. The process to mount them back differs slightly. Check your system's configuration to determine the version in use.
One way to identify the version is by checking the /proc/filesystems file for entries related to specific cgroup controllers (e.g., cpuset). If entries exist and don't have "nodev" at the end, it suggests cgroup v1.

Mount cgroup v1:

• If cgroup v1 is in use:

mkdir /sys/fs/cgroup # Create the mount point if it doesn't exist
mount -t cgroup none /sys/fs/cgroup # Mount the cgroup filesystem

Mount cgroup v2:

• For cgroup v2, the process might involve additional configuration depending on the systemd settings.
• Check if systemd.unified_cgroup_hierarchy=1 is set in the kernel boot options. This enables the unified hierarchy for cgroup v2.
• If the option is not set (or set to 0), the steps are similar to v1:

mkdir /sys/fs/cgroup # Create the mount point if it doesn't exist
mount -t cgroup2 none /sys/fs/cgroup # Mount the cgroup2 filesystem

Important Notes:

• root privileges are required to perform the commands.
• Some cgroup controllers might require additional configuration after mounting (e.g., creating specific cgroup directories and setting control values).

For more specific steps or if issues are encountered, it is recommended to consult the system's OS documentation.