A case of Linux Cgroup not being uninstalled completely

With mount-t Cgroup-o cpu,memory my_virt_res/cgroups/my_cpu_and_mem mount the Cgroup file system, use the

Cgcreate-g CPU:/MY_CPU Create a control group under/CGROUPS/MY_CPU_AND_MEM/MY_CPU,

Then a mis-operation unloaded the file system on the/CGROUPS/MY_CPU_AND_MEM: Umount/cgroups/my_cpu_and_mem

At this point,/proc/mounts has no content Cgroup file system, but/proc/cgroups also has subsys in the hierarchy, Lssubsys-i can also see:

Cat/proc/cgroups
#subsys_name Hierarchy Num_cgroups Enabled
Cpuset 0 1 1
NS 0 1 1
CPU 2 1
CPUACCT 0 1 1
Memory 2 1
Devices 0 1 1
Freezer 0 1 1
NET_CLS 0 1 1
Blkio 0 1 1
Perf_event 0 1 1
Net_prio 0 1 1

Attempting to mount a cgroup that contains only CPU or memory failed with error device busy

You can only re-mount the cpu,memory as a whole cgroup, and finally execute cgclear to completely uninstall Cgroup.

A case of Linux Cgroup not being uninstalled completely