From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751950AbeBZVw5 (ORCPT ); Mon, 26 Feb 2018 16:52:57 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:51604 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751586AbeBZVwu (ORCPT ); Mon, 26 Feb 2018 16:52:50 -0500 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 11/20] rcu: More clearly identify grace-period kthread stack dump Date: Mon, 26 Feb 2018 13:53:01 -0800 X-Mailer: git-send-email 2.5.2 In-Reply-To: <20180226215219.GA27379@linux.vnet.ibm.com> References: <20180226215219.GA27379@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18022621-0056-0000-0000-0000042458A3 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00008601; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000254; SDB=6.00995530; UDB=6.00506033; IPR=6.00774858; MB=3.00019751; MTD=3.00000008; XFM=3.00000015; UTC=2018-02-26 21:52:48 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18022621-0057-0000-0000-00000866621C Message-Id: <1519681990-31349-11-git-send-email-paulmck@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-02-26_07:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1802260274 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It is not always obvious that the stack dump from a starved grace-period kthread isn't instead that of a CPU stalling the current grace period. This commit therefore adds a pr_err() flagging these dumps. Reported-by: Peter Zijlstra 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 86fc087c7777..4d7c727020f0 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1350,6 +1350,7 @@ static void rcu_check_gp_kthread_starvation(struct rcu_state *rsp) rsp->gp_kthread ? rsp->gp_kthread->state : ~0, rsp->gp_kthread ? task_cpu(rsp->gp_kthread) : -1); if (rsp->gp_kthread) { + pr_err("RCU grace-period kthread stack dump:\n"); sched_show_task(rsp->gp_kthread); wake_up_process(rsp->gp_kthread); } -- 2.5.2