Any trick to remove a D-state dead process without rebooting?

Hi, fellows: Does anyone know of any hacks that remove a D-state dead process whose parent is pid=1 (actually systemd), without rebooting? Someone posed a trick on the net, but not sure how he did it: https://serverfault.com/questions/76263/how-to-kill-a-defunct-process-with-p... Because the dead process is wrapped as a Systemd unit, I've also asked at Systemd's mailing list without avail: https://lists.freedesktop.org/archives/systemd-devel/2017-December/039941.ht... Appreciate any hint or even dirty hacks! Thanks in advance! Yunchih