Once you kill 'fs', the entire scope of files disappears, that is, Minix
3 no longer "knows" what a file is (and with that, the entire scope of
and concept of a "file" is lost), and since 'pm' (which is where the
call to restart a server [being that it's just starting a process like
anything else] ultimately goes) only knows of files as viable sources
for images upon which to create new processes from, killing 'fs' kills
your entire system, because 'pm' can no longer acquire a new image in
which to create a new process from.
Also, killing 'pm' kills your system because Minix 3 no longer "knows"
what a process is, and is thus unable to use 'rs' (nor can it give CPU
time to any processes, since there is no longer a such thing as a
"process", in a sense). Killing 'pm' subsequently kills all processes in
both the sense of parent-child process semantics of traditional UNIX,
and also in the sense that there is nothing to manage their execution
contexts, or to give processes execution contexts in the first place.
Yes, user-mode processes are managed and timesliced by... a user-mode
process. In one sense, this is extremely idiosyncratic, but in another,
it makes perfect sense.
Hope that helps.
If I got ANY of this wrong, please correct it. Remember, to err is to be