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Subject: Re: [Regression] 2.6.24-git9: RT sched mishandles artswrapper
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From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>,
       LKML <linux-kernel@vger.kernel.org>,
       Andrew Morton <akpm@linux-foundation.org>
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Date: Fri, 01 Feb 2008 13:09:56 +0100
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On Fri, 2008-02-01 at 12:50 +0100, Rafael J. Wysocki wrote:
> On Friday, 1 of February 2008, Peter Zijlstra wrote:

> > > It arts run as root, or does it use RLIMIT_RTPRIO to allow users to
> > > execute realtime tasks?
> 
> artswrapper is setuid root and RLIMIT_RTPRIO is apparently not used.
> Still, artswrapper is running as a regular user, so it most probably drops
> privileges early.
> 
> BTW, it fails while running the artsmessage utility used for displaying arts
> error messages, so I guess there's an error in arts that this thing tries to
> display and deadlocks (or something like that).
> 
> Should I test the patch nevertheless?

Don't think that would help any in this situation. The thing to look out
for are RT tasks running with a different uid than 0.

This patch would only stop a task from obtaining RT class scheduling
when already in a (misconfigured) group. If the task is RT and then
switches group another - similar - thing is needed.

Does this artsmessage thing also run with RT priority?