From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762408Ab2FVPf0 (ORCPT ); Fri, 22 Jun 2012 11:35:26 -0400 Received: from e39.co.us.ibm.com ([32.97.110.160]:41674 "EHLO e39.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754815Ab2FVPfZ (ORCPT ); Fri, 22 Jun 2012 11:35:25 -0400 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, eric.dumazet@gmail.com, darren@dvhart.com, fweisbec@gmail.com, sbw@mit.edu, patches@linaro.org, "Paul E. McKenney" , "Paul E. McKenney" Subject: [PATCH tip/core/rcu 17/17] rcu: Add check for CPUs going offline with callbacks queued Date: Fri, 22 Jun 2012 08:35:12 -0700 Message-Id: <1340379312-6684-17-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.8 In-Reply-To: <1340379312-6684-1-git-send-email-paulmck@linux.vnet.ibm.com> References: <20120622153501.GA6626@linux.vnet.ibm.com> <1340379312-6684-1-git-send-email-paulmck@linux.vnet.ibm.com> X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12062215-4242-0000-0000-000002153186 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Paul E. McKenney" If a CPU goes offline with callbacks queued, those callbacks might be indefinitely postponed, which can result in a system hang. This commit therefore inserts warnings for this condition. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney --- kernel/rcutree.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index c0cc41f..f849202 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1506,6 +1506,9 @@ static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp) raw_spin_unlock_irqrestore(&rnp->lock, flags); if (need_report & RCU_OFL_TASKS_EXP_GP) rcu_report_exp_rnp(rsp, rnp, true); + WARN_ONCE(rdp->qlen != 0 || rdp->nxtlist != NULL, + "rcu_cleanup_dead_cpu: Callbacks on offline CPU %d: qlen=%lu, nxtlist=%p\n", + cpu, rdp->qlen, rdp->nxtlist); } #else /* #ifdef CONFIG_HOTPLUG_CPU */ -- 1.7.8