Trouble killing processes in SysV/AT

[Guy Harris]

> | You ask about processes that refuse to die.  (Calling them "immortal"
> | confers a positive aura that is probably undeserved.  Normally these
> | processes are in a useless state, and might better be referred to as
> | members of the "undead".)
> 
> The canonical term for such a process is "zombie."

Wrong.  A "zombie" is a process that has already completed dying, but whose
corpse hasn't been picked up by its parent yet.  The corpse has already been
picked clean (it has no address space, for instance).  This is a misuse of the
term "zombie", but we're stuck with it.

A *live* process that refuses to die, which is what was originally being
discussed, is a different matter.  A very common cause of this is a driver that
blocks for a very long time - possibly forever - with a priority less than or
equal to PZERO.