Sporadic kubectl exec issue Ubuntu 18.04

[rastislavs]

In the Contiv/VPP CI, we sporadically see the following issue by executing kubectl exec ...:

OCI runtime exec failed: exec failed: container_linux.go:348: starting container process caused "process_linux.go:90: adding pid 12012 to cgroups caused \"failed to write 12012 to cgroup.procs: write /sys/fs/cgroup/cpu,cpuacct/kubepods/besteffort/podeb5707e6-cb5b-11e8-9c69-024d82c4d587/8f696a77036051847f87e9b0dd86d0ff44ec03073e5baebc199fe9d1fd8fe607/cgroup.procs: invalid argument\"": unknown

This started to appear on Ubuntu 18.04. No issues with Ubuntu 16.04.

[rastislavs]

The root cause seems to be https://github.com/opencontainers/runc/issues/1884

[rastislavs]

still present on k8s 1.14.2