LXC and cgroup.memory on Debian

Two days ago on Lurch, I was trying to show/set a memory limit for a container (LXC), using "lxc-cgroup -n <container> memory.limit_in_bytes"

Unfortunately, I got the message "lxc-cgroup: missing cgroup subsystem", that I've firstly intended as "I couldn't mount this cgroup at this session"

Briefly, asking about memory cgroup to LXC, everything was ok

while asking to linux not

Another confusing point to me, was the check of the dmesg output, that showed memory cgroup between the others

So, after a little of googling, I have understood like, the memory cgroup  is just not enabled on Debian by default. That because having the cgroup.memory enabled, costs around 15Mb of ram, that is obviously a waste if you don't use that cgroup

In order to have the availability of said cgroup, you need to instruct the Grub by /etc/default/grub with the boot parameter cgroup_enable=memory

The amount of memory reserved to the cgroup nos is printed out during the boot time

In the end I could set my cgroup memory limit