Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965144AbbDQNhK (ORCPT ); Fri, 17 Apr 2015 09:37:10 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:34092 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965085AbbDQNhC (ORCPT ); Fri, 17 Apr 2015 09:37:02 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Brian Silverman , "Peter Zijlstra (Intel)" , austin@peloton-tech.com, Ingo Molnar Subject: [PATCH 3.19 046/101] sched: Fix RLIMIT_RTTIME when PI-boosting to RT Date: Fri, 17 Apr 2015 15:28:34 +0200 Message-Id: <20150417132516.400795361@linuxfoundation.org> X-Mailer: git-send-email 2.3.5 In-Reply-To: <20150417132514.379828774@linuxfoundation.org> References: <20150417132514.379828774@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2061 Lines: 53 3.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Brian Silverman 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: Greg Kroah-Hartman --- 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 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/