Comment 7 for bug 1765980

This has expired, but affects me too here.
I'm specifically using Proxmox, which uses Ubuntu for upstream kernel - currently at 4.15.18, and I see the same symptoms.
Specifically LXC, specifically at stop and specifically kworker using 100% of one core and preventing startup of other containers.
I've found that this isn't present in Proxmox's own kernel 4.15.10-1 specifically.