Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965578AbbD0VeW (ORCPT ); Mon, 27 Apr 2015 17:34:22 -0400 Received: from ip4-83-240-67-251.cust.nbox.cz ([83.240.67.251]:49754 "EHLO ip4-83-240-18-248.cust.nbox.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S965306AbbD0Vc7 (ORCPT ); Mon, 27 Apr 2015 17:32:59 -0400 From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Brian Silverman , "Peter Zijlstra (Intel)" , austin@peloton-tech.com, Ingo Molnar , Jiri Slaby Subject: [PATCH 3.12 24/83] sched: Fix RLIMIT_RTTIME when PI-boosting to RT Date: Mon, 27 Apr 2015 23:31:55 +0200 Message-Id: X-Mailer: git-send-email 2.3.5 In-Reply-To: <3426bb8de3a655aa6668e92ee92eb35f0db86582.1430159990.git.jslaby@suse.cz> References: <3426bb8de3a655aa6668e92ee92eb35f0db86582.1430159990.git.jslaby@suse.cz> In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2205 Lines: 59 From: Brian Silverman 3.12-stable review patch. If anyone has any objections, please let me know. =============== 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 Signed-off-by: Peter Zijlstra (Intel) Cc: austin@peloton-tech.com Link: http://lkml.kernel.org/r/1424305436-6716-1-git-send-email-brian@peloton-tech.com Signed-off-by: Ingo Molnar Signed-off-by: Jiri Slaby --- kernel/sched/core.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index f09e22163be3..0030db473c99 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3060,8 +3060,11 @@ void rt_mutex_setprio(struct task_struct *p, int prio) if (rt_prio(prio)) p->sched_class = &rt_sched_class; - else + else { + if (rt_prio(oldprio)) + p->rt.timeout = 0; p->sched_class = &fair_sched_class; + } p->prio = prio; -- 2.3.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/