3.19-stable review patch. If anyone has any objections, please let me know.
------------------ From: Brian Silverman <br...@peloton-tech.com> commit 746db9443ea57fd9c059f62c4bfbf41cf224fe13 upstream. When non-realtime tasks get priority-inheritance boosted to a realtime scheduling class, RLIMIT_RTTIME starts to apply to them. However, the counter used for checking this (the same one used for SCHED_RR timeslices) was not getting reset. This meant that tasks running with a non-realtime scheduling class which are repeatedly boosted to a realtime one, but never block while they are running realtime, eventually hit the timeout without ever running for a time over the limit. This patch resets the realtime timeslice counter when un-PI-boosting from an RT to a non-RT scheduling class. I have some test code with two threads and a shared PTHREAD_PRIO_INHERIT mutex which induces priority boosting and spins while boosted that gets killed by a SIGXCPU on non-fixed kernels but doesn't with this patch applied. It happens much faster with a CONFIG_PREEMPT_RT kernel, and does happen eventually with PREEMPT_VOLUNTARY kernels. Signed-off-by: Brian Silverman <br...@peloton-tech.com> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Cc: aus...@peloton-tech.com Link: http://lkml.kernel.org/r/1424305436-6716-1-git-send-email-br...@peloton-tech.com Signed-off-by: Ingo Molnar <mi...@kernel.org> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- kernel/sched/core.c | 2 ++ 1 file changed, 2 insertions(+) --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3079,6 +3079,8 @@ void rt_mutex_setprio(struct task_struct } else { if (dl_prio(oldprio)) p->dl.dl_boosted = 0; + if (rt_prio(oldprio)) + p->rt.timeout = 0; p->sched_class = &fair_sched_class; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
