From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756856AbdGXWZx (ORCPT ); Mon, 24 Jul 2017 18:25:53 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:58967 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756617AbdGXWXt (ORCPT ); Mon, 24 Jul 2017 18:23:49 -0400 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, fweisbec@gmail.com, oleg@redhat.com, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 10/13] rcutorture: Add task's CPU for rcutorture writer stalls Date: Mon, 24 Jul 2017 15:23:40 -0700 X-Mailer: git-send-email 2.5.2 In-Reply-To: <20170724222326.GA15933@linux.vnet.ibm.com> References: <20170724222326.GA15933@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 17072422-0040-0000-0000-000003850CB9 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007419; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000214; SDB=6.00892385; UDB=6.00446029; IPR=6.00672549; BA=6.00005489; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00016356; XFM=3.00000015; UTC=2017-07-24 22:23:45 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17072422-0041-0000-0000-0000077929ED Message-Id: <1500935023-16620-10-git-send-email-paulmck@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-07-24_14:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=1 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1706020000 definitions=main-1707240344 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It appears that at least some of the rcutorture writer stall messages coincide with unusually long CPU-online operations, for example, no fewer than 205 seconds in a recent test. It is of course possible that the writer stall is not unrelated to this unusually long CPU-hotplug operation, and so this commit adds the rcutorture writer task's CPU to the stall message to gain more information about this possible connection. Signed-off-by: Paul E. McKenney --- kernel/rcu/rcutorture.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index b48d2107f176..75ac749ced7c 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -1319,11 +1319,12 @@ rcu_torture_stats_print(void) srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gpnum, &completed); wtp = READ_ONCE(writer_task); - pr_alert("??? Writer stall state %s(%d) g%lu c%lu f%#x ->state %#lx\n", + pr_alert("??? Writer stall state %s(%d) g%lu c%lu f%#x ->state %#lx cpu %d\n", rcu_torture_writer_state_getname(), rcu_torture_writer_state, gpnum, completed, flags, - wtp == NULL ? ~0UL : wtp->state); + wtp == NULL ? ~0UL : wtp->state, + wtp == NULL ? -1 : (int)task_cpu(wtp)); show_rcu_gp_kthreads(); rcu_ftrace_dump(DUMP_ALL); } -- 2.5.2