lxc-cgroup -n 11 cpuacct.stat is empty in buster

[Marc SCHAEFER <schaefer@alphanet.ch>]

Hello,

I just updated a jessie system to buster. Kudos to the packagers of
lxc, the upgrade script worked and the containers work like a charm.

However, I have an issue with some lxc munin plugins I use. Namely
they don't show anything.

It reduces to the following problem:

   lxc-cgroup -n 11 cpuacct.stat
   (and also lxc-cgroup -n 11 cpu.stat)

is now empty (the same is valid for other cgroup stuff).

before, it would output something like:

   user 9650090
   system 1645066

I found this reported here: https://github.com/lxc/lxc/issues/2742
and here: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=929926
however, this is supposedly fixed in 1:3.1.0+really3.0.3-8 which
is what is installed on my system.

So, maybe it's a config option I missed ?

lxc-checkconfig says:
   Kernel configuration found at /boot/config-4.19.0-5-amd64
   --- Namespaces ---
   Namespaces: enabled
   Utsname namespace: enabled
   Ipc namespace: enabled
   Pid namespace: enabled
   User namespace: enabled
   Network namespace: enabled
   
   --- Control groups ---
   Cgroups: enabled
   
   Cgroup v1 mount points: 
   /sys/fs/cgroup/systemd
   /sys/fs/cgroup/pids
   /sys/fs/cgroup/perf_event
   /sys/fs/cgroup/freezer
   /sys/fs/cgroup/cpu,cpuacct
   /sys/fs/cgroup/net_cls,net_prio
   /sys/fs/cgroup/blkio
   /sys/fs/cgroup/rdma
   /sys/fs/cgroup/devices
   /sys/fs/cgroup/memory
   /sys/fs/cgroup/cpuset
   
   Cgroup v2 mount points: 
   /sys/fs/cgroup/unified
   
   Cgroup v1 clone_children flag: enabled
   Cgroup device: enabled
   Cgroup sched: enabled
   Cgroup cpu account: enabled
   Cgroup memory controller: enabled
   Cgroup cpuset: enabled
   
   --- Misc ---
   Veth pair device: enabled, loaded
   Macvlan: enabled, not loaded
   Vlan: enabled, not loaded
   Bridges: enabled, loaded
   Advanced netfilter: enabled, loaded
   CONFIG_NF_NAT_IPV4: enabled, loaded
   CONFIG_NF_NAT_IPV6: enabled, not loaded
   CONFIG_IP_NF_TARGET_MASQUERADE: enabled, not loaded
   CONFIG_IP6_NF_TARGET_MASQUERADE: enabled, not loaded
   CONFIG_NETFILTER_XT_TARGET_CHECKSUM: enabled, loaded
   CONFIG_NETFILTER_XT_MATCH_COMMENT: enabled, not loaded
   FUSE (for use with lxcfs): enabled, loaded
   
   --- Checkpoint/Restore ---
   checkpoint restore: enabled
   CONFIG_FHANDLE: enabled
   CONFIG_EVENTFD: enabled
   CONFIG_EPOLL: enabled
   CONFIG_UNIX_DIAG: enabled
   CONFIG_INET_DIAG: enabled
   CONFIG_PACKET_DIAG: enabled
   CONFIG_NETLINK_DIAG: enabled
   File capabilities: 
   
   Note : Before booting a new kernel, you can check its configuration
   usage : CONFIG=/path/to/config /usr/bin/lxc-checkconfig
 
Would you have any idea how to fix this ?

Thank you for your input.