RPi 4: cgroups: memory cgroup not supported on this system

[pdcastro]

As originally reported in:

• https://forums.balena.io/t/fold-on-pi-4-keeps-restarting-the-ui/216098
• User reports RPi4 2GB has it's UI service on a restart loop balena-labs-projects/rosetta-at-home#55

Appears to happen on the RPi 4 only (I wonder if it would also affect the RPi 3 64 bits...)

On investigation, @pipex found that the supervisor fails to start a container (restart loop) because:

[...] the supervisor sets the memReservation value correctly when creating the container but it looks like the engine fails to apply it, the supervisor queries the container state which reports MemoryReservation: 0 and we get the loop.
Inspecting the container (you have to stop the supervisor before it can kill the service), shows the value is not set for the ui service [the app container in a restart loop].
The engine also throws the warning
Nov 26 13:28:46 e09a3cd balenad[1448]: time="2020-11-26T13:28:46.131725111Z" level=warning msg="OOM monitoring failed" error="cgroups: memory cgroup not supported on this system"
Googling the message I got to moby/moby#35587 where they propose the fix of adding cgroup_enable=memory to cmdline.txt. I tested on my RPI4 and the loop stops.
Not sure if there is something that changed in the OS or the engine that caused this issue to show up. Maybe people in (at)(at)os or @robertgzr might know more.

Creating this meta-balena GitHub issue on the assumption that it is an OS issue, and/or in case it helps to gather more information.

[jellyfish-bot]

[pdcastro] This issue has attached support thread https://jel.ly.fish/2890ed0a-d515-4a58-b1f0-a0eb17b115f4

[alexgg]

Moving to the raspberrypi integration repo balena-os/balena-raspberrypi#574