On Friday, 1 of February 2008, Peter Zijlstra wrote: > > On Fri, 2008-02-01 at 08:44 +0100, Peter Zijlstra wrote: > > On Fri, 2008-02-01 at 03:04 +0100, Rafael J. Wysocki wrote: > > > On Friday, 1 of February 2008, Rafael J. Wysocki wrote: > > > > Hi, > > > > > > > > This is related to the problem I reported earlier this week: > > > > http://lkml.org/lkml/2008/1/30/554 > > > > > > > > Apparently artswrapper, run by KDE in openSUSE 10.3 with a real time > > > > priority, > > > > is mishandled by the scheduler. The problem is that after the user > > > > logs out, > > > > artswrapper stays in TASK_RUNNING forever and prevents other tasks from > > > > being > > > > scheduled on the CPU occupied by it. In this state it also breaks > > > > suspend and > > > > hibernation (it cannot be frozen). > > > > > > > > Since the problem is 100% reproducible on my test boxes, I carried out a > > > > bisection which turned out the following commit: > > > > > > > > commit 6f505b16425a51270058e4a93441fe64de3dd435 > > > > Author: Peter Zijlstra <[EMAIL PROTECTED]> > > > > Date: Fri Jan 25 21:08:30 2008 +0100 > > > > > > > > sched: rt group scheduling > > > > > > > > I'm now checking if the problem disappears after reverting this patch > > > > (along a > > > > couple of dependent ones). > > > > > > Yes, it does. > > > > > > Please let me know what I can do to debug it further. > > > > 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? > If the latter, does this help: > > diff --git a/kernel/sched.c b/kernel/sched.c > index ba4c880..bb76cbc 100644 > --- a/kernel/sched.c > +++ b/kernel/sched.c > @@ -4563,6 +4563,15 @@ recheck: > return -EPERM; > } > > +#ifdef CONFIG_FAIR_GROUP_SCHED > + /* > + * Do not allow realtime tasks into groups that have no runtime > + * assigned. > + */ > + if (rt_policy(policy) && task_group(p)->rt_ratio == 0) > + return -EPERM; > +#endif > + > retval = security_task_setscheduler(p, policy, param); > if (retval) > return retval; > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
