memory cgroup disabled on Ubuntu Core 18

[Ian Johnson]

On Ubuntu Core 18, the memory cgroup is disabled, it seems that it needs to be manually enabled. I was able to enable it by adding `cgroup_enable=memory cgroup_memory=1` to the kernel command line, but on Ubuntu I think the memory cgroup should be enabled by default shouldn't it?

$ cat /proc/cgroups
#subsys_name hierarchy num_cgroups enabled
cpuset 2 1 1
cpu 4 100 1
cpuacct 4 100 1
blkio 5 100 1
memory 0 109 0
devices 6 100 1
freezer 9 4 1
net_cls 3 1 1
perf_event 10 1 1
net_prio 3 1 1
pids 8 107 1
rdma 7 1 1

I see this with

Linux localhost 5.4.0-1043-raspi #47~18.04.1-Ubuntu SMP PREEMPT Mon Aug 23 14:39:46 UTC 2021 aarch64 aarch64 aarch64 GNU/Linux

on Ubuntu Core 18, but folks have informed me that the same is true on Ubuntu Core 20 as well.

[Ian Johnson (anonymouse67)]

Also an interesting datapoint is that on Ubuntu 21.04 Server on my pi, the memory cgroup is enabled:

ubuntu@ubuntu:~$ cat /proc/cgroups
#subsys_name hierarchy num_cgroups enabled
cpuset 7 1 1
cpu 2 125 1
cpuacct 2 125 1
blkio 11 125 1
memory 5 140 1
devices 12 126 1
freezer 8 4 1
net_cls 9 1 1
perf_event 6 1 1
net_prio 9 1 1
hugetlb 3 1 1
pids 10 132 1
rdma 4 1 1
ubuntu@ubuntu:~$ uname -a
Linux ubuntu 5.11.0-1017-raspi #18-Ubuntu SMP PREEMPT Mon Aug 23 07:34:31 UTC 2021 aarch64 aarch64 aarch64 GNU/Linux

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:

apport-collect 1945369

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Ian Johnson (anonymouse67)]

apport-collect is not available on ubuntu core

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:

apport-collect 1945369

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Patrick Lamprecht (ch4s3r)]

How where you able to set the kernel command line args permanentely on ubuntu core?

[Patrick Lamprecht (ch4s3r)]

Discovered how do to it, had to add 'cgroup_enable=memory cgroup_memory=1' to '/ubuntu-seed/cmdline' of the sd card.

[Michaelian Ennis (mennis-d)]

Thanks Patrick, I found that this was accessible on host as /writable/system-data/var/lib/snapd/seed/cmdline.txt and updating it there worked (after reboot).

[Will Charlton (williamcharltonengineering)]

Thanks Michaelian - this also worked for me using Ubuntu Core latest.