mount list ( mount (2) and umount (2)) in either mount namespace will not (by default ... automatic, controlled propagation of mount (2) and umount (2) events between namespaces (o…cgroup filesystem can be unmounted using the umount (8) command, as in the following example ... umount /sys/fs/cgroup/pids But note well : a cgroup filesystem is unmounted onlyadministration operations including: quotactl (2), mount (2), umount (2), pivot_root (2), swapon (2), swapoffsystemd-udevd.service (8) — Device event managing daemon systemd-umount (1) — Establish and destroy transient mountpropagate mount events # to other namespaces sh2# umount /sys/fs/cgroup/freezer sh2# mount -t cgroup -o freezeruserdbctl (1) --umask homectl (1) --umount systemd-dissect (1), systemd-mount (1) --uname systemd-measure