Linux Troubleshooting - Processes That Won't Die

uninterruptible sleep process or "D" in process status(S)

Reboot is easiest after you have tried everything else

https://linuxgazette.net/issue83/tag/6.html

Ran into this with LXD ZFS storage pool.

You get a bunch of these and just can't seem to kill or clean-up. You may have to hard reboot if soft doesn't work.

zfs get -H