cgroupfs-mount mounts /sys/fs/cgroup but cgroupfs-umount does not unmount it.

Is there any reason for that?
I've extended my script with an umount command.

diff --git a/cgroupfs-umount b/cgroupfs-umount
index 994b66e..13458f4 100644
--- a/cgroupfs-umount
+++ b/cgroupfs-umount
@@ -28,4 +28,10 @@ for sys in *; do
   fi
 done

+# unmount /sys/fs/cgroup
+cd /sys/fs
+if mountpoint -q /sys/fs/cgroup; then
+  umount /sys/fs/cgroup
+fi
+
 exit 0

I'm setting up a Docker image for AWS Greengrass, which requires cgroups directories to be mounted:
http://docs.aws.amazon.com/greengrass/latest/developerguide/gg-dg.pdf

Specifically (which actually appears to be out of date):

curl https://raw.githubusercontent.com/tianon/cgroupfsmount/951c38ee8d802330454bdede20d85ec1c0f8d312/cgroupfs-mount
> cgroupfs-mount.sh
chmod +x cgroupfs-mount.sh
sudo bash ./cgroupfs-mount.sh

In my Dockerfile, I'm using the apt-get install cgroupsfs-mount approach:

Step 9/15 : RUN sudo cgroupfs-mount
 ---> Running in cc187c3fb61f
mount: permission denied
mount: permission denied
mount: permission denied
mount: permission denied
mount: permission denied
mount: permission denied
mount: permission denied
mount: permission denied
mount: permission denied
mount: permission denied
mount: permission denied
mount: permission denied

I added some debug echos, since it wasn't clear where the permission denied messages where coming from:

Step 10/16 : RUN sudo bash /app/cgroupfs-mount.sh
 ---> Running in ced257974766
making directory cpuset
cpuset not mounted
mount: permission denied
tried to mount cpuset, but failed, removing it
making directory cpu
cpu not mounted
mount: permission denied
tried to mount cpu, but failed, removing it
making directory cpuacct
cpuacct not mounted
mount: permission denied
tried to mount cpuacct, but failed, removing it
making directory blkio
blkio not mounted
mount: permission denied
tried to mount blkio, but failed, removing it
making directory memory
memory not mounted
mount: permission denied
tried to mount memory, but failed, removing it
making directory devices
devices not mounted
mount: permission denied
tried to mount devices, but failed, removing it
making directory freezer
freezer not mounted
mount: permission denied
tried to mount freezer, but failed, removing it
making directory net_cls
net_cls not mounted
mount: permission denied
tried to mount net_cls, but failed, removing it
making directory perf_event
perf_event not mounted
mount: permission denied
tried to mount perf_event, but failed, removing it
making directory net_prio
net_prio not mounted
mount: permission denied
tried to mount net_prio, but failed, removing it
making directory hugetlb
hugetlb not mounted
mount: permission denied
tried to mount hugetlb, but failed, removing it
making directory pids
pids not mounted
mount: permission denied
tried to mount pids, but failed, removing it

I'm not entirely sure what's going on here, or why the mount is failing, thoughts?

There seems to be some really important additions like memory hierarchy that are unreleased. Can a new version be released, so it can be used by softwares like buildroot which is using v0.4?

I request a suggestion that rename cgroups-mount/cgroups-umount to mount.cgroups/umount.cgroups, as a file system mount command naming routine under most linux distributions, like any other mount cmd, mount.cifs, mount.fuse, mount.glusterfs, mount.lowntfs-3g, mount.nfs, mount.nfs4, mount.ntfs, mount.ntfs-3g, mount.ploop.

I'm trying to get docker running on my Server running Ubuntu 14.04 and your package was mentioned as a possible solution to this problem.

However, I have no idea how to best install your package, could you elaborate in the README.md?

This source code doesn't have a license, as far as I can tell. According to https://choosealicense.com/no-permission/, a project without a license is "all rights reserved" and prohibits users from compiling/distributing binaries of this software. Please add a license. There is a relatively exhaustive list at https://choosealicense.com/appendix. Also, by adding a license this (depending on the license) allows third parties such as unix-like distributions to package this software and distribute binaries. Thank you for your consideration!
DISCLAIMER: I'm not a laywer, this isn't legal advice.

I am working on Android and tried to run this script to start docker daemon. but running script returns segmentation fault. it is not bounded to only one part of the code. i tried to comment one part and test next commands. on mounting commands it gives me segmentation fault.
Please help me through this issue,
thanks

Is possible to install cgroupfs-mount on alpine?

Related issue k3s-io/k3s#1387

Cheers.