Hi there,
I have recently updated my unraid server (from 6.11.5) to 6.12.4, and i am now running into a pretty unique issue. Every time a new SSH session is created, a new cgroup is created. Unfortunately this new cgroup does not get cleaned up when the session is closed.
I use SSH to run some icinga monitoring checks on the host. this adds up pretty fast, reaching the cgroup limit of 65535 within a few weeks. When the limit is reached, i cannot start new docker containers:
docker: error response from daemon: failed to create shim task: oci runtime create failed: runc create failed: unable to start container process: unable to apply cgroup configuration: mkdir /sys/fs/cgroup/docker/XXX: no space left on device: unknown.
Restarting the SSH Daemon does not appear to work, i have to restart the server to clear the defunct cgroups.
The amount of cgroups can be viewed using:
cat /proc/cgroups
#subsys_name hierarchy num_cgroups enabled
cpuset 0 52 1
cpu 0 52 1
cpuacct 0 52 1
blkio 0 52 1
memory 0 52 1
devices 0 52 1
freezer 0 52 1
net_cls 0 52 1
perf_event 0 52 1
net_prio 0 52 1
hugetlb 0 52 1
pids 0 52 1
All these cgroups appear as /sys/fs/cgroup/cXX:
/sys/fs/cgroup# ls
c1/ c15/ c20/ c4/ cgroup.controllers cgroup.threads io.stat
c10/ c16/ c21/ c5/ cgroup.max.depth cpu.stat machine/
c11/ c17/ c22/ c6/ cgroup.max.descendants cpuset.cpus.effective memory.numa_stat
c12/ c18/ c23/ c7/ cgroup.procs cpuset.mems.effective memory.reclaim
c13/ c19/ c24/ c8/ cgroup.stat docker/ memory.stat
c14/ c2/ c3/ c9/ cgroup.subtree_control elogind/
I have found one similar issue on the interwebs from 6 years ago:
https://stackoverflow.com/questions/45690117/ubuntu-server-every-ssh-connect-creates-non-deleted-cgroup
It appears to be a pretty fringe issue. I do not have any other servers to try and reproduce this. i don't know if this is the right place for this issue, i can imagine this may go way deeper into openSSH/docker itself than just the plugin.
Any help is appreciated.
