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Subject: Re: Where is RLIMIT_RT_CPU?
From: Lee Revell <rlrevell@joe-job.com>
To: Jean-Marc Valin <Jean-Marc.Valin@USherbrooke.ca>
Cc: Arjan van de Ven <arjan@infradead.org>,
       Esben Nielsen <nielsen.esben@googlemail.com>,
       linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>
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On Sun, 2006-07-16 at 01:04 +1000, Jean-Marc Valin wrote:
> > as long as you can fork and exec as many of those processes as you want
> > a per process rlimit is useless security wise... an evil user just fires
> > off a second process just before the first one gets killed and a non-RT
> > root still is starved out.
> 
> Of course, which is why the idea is for the limit to be global, across
> all non-root users. AFAIK, that's what Ingo's original (pre-2.6.12)
> patch did and also what Con Kolivas' SCHED_ISO patch does. That's also
> why I think it would be very hard (if possible at all) to do this in
> user space.

I don't think it's a problem.  If the admin does not want non-root users
to be able to lock up the machine, just don't put them in the realtime
group.

Lee