Re: [PATCH] Reserve N process to root

[David Newall <david@davidnewall.com>]

Valdis.Kletnieks@vt.edu wrote:
> What David meant was that "root will always have a slot" doesn't *actually*
> help unless you *also* have a way to actually *spawn* such a process.  In order
> to do the ps, kill, and so on that you need to recover, you need to already
> have either a root shell available, or a way to *get* a root shell that doesn't
> rely on a non-root process (so /bin/su doesn't help here).

That's right, although it's worse than that.  You need to have a process 
with CAP_SYS_ADMIN.  If root processes normally have that capability 
then the reserved slots may well disappear before you notice a problem.  
If root processes normally don't have it, then you need to guarantee 
that one is already running.