I cannot unmount a filesystem because zombie processes (or processes in the "D" state) are holding on to files on the filesystem. How can I kill these processes so I can unmount the filesystem?

A process with the parent ID 1 means that it is child process of init. The process init is protected from even the command kill -9 init (which is a command that usually means "kill this process, regardless of anything else").

These process cannot be killed without a reboot. To kill a zombie child process of init, the computer must be r...