From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965089AbcDLPCS (ORCPT ); Tue, 12 Apr 2016 11:02:18 -0400 Received: from e37.co.us.ibm.com ([32.97.110.158]:35599 "EHLO e37.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964872AbcDLPCK (ORCPT ); Tue, 12 Apr 2016 11:02:10 -0400 X-IBM-Helo: d03dlp03.boulder.ibm.com X-IBM-MailFrom: paulmck@linux.vnet.ibm.com X-IBM-RcptTo: linux-kernel@vger.kernel.org From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 6/6] rcu: Dump ftrace buffer when kicking grace-period kthread Date: Tue, 12 Apr 2016 08:02:22 -0700 Message-Id: <1460473342-20836-6-git-send-email-paulmck@linux.vnet.ibm.com> X-Mailer: git-send-email 2.5.2 In-Reply-To: <20160412150157.GA19367@linux.vnet.ibm.com> References: <20160412150157.GA19367@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16041215-0025-0000-0000-00002CD80B62 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If it is necessary to kick the grace-period kthread, that is a good time to dump the trace buffer in order to learn why kicking was needed. This commit therefore does the dump. Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index a739292be605..86edb92276d3 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1266,6 +1266,7 @@ static void rcu_stall_kick_kthreads(struct rcu_state *rsp) j = READ_ONCE(rsp->jiffies_kick_kthreads); if (time_after(jiffies, j) && rsp->gp_kthread) { WARN_ONCE(1, "Kicking %s grace-period kthread\n", rsp->name); + rcu_ftrace_dump(DUMP_ALL); wake_up_process(rsp->gp_kthread); WRITE_ONCE(rsp->jiffies_kick_kthreads, j + HZ); } -- 2.5.2