From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8F728C43381 for ; Tue, 26 Mar 2019 23:31:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6208A208E4 for ; Tue, 26 Mar 2019 23:31:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733109AbfCZXbr (ORCPT ); Tue, 26 Mar 2019 19:31:47 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:41920 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733004AbfCZXb1 (ORCPT ); Tue, 26 Mar 2019 19:31:27 -0400 Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x2QNT6lE123570 for ; Tue, 26 Mar 2019 19:31:26 -0400 Received: from e12.ny.us.ibm.com (e12.ny.us.ibm.com [129.33.205.202]) by mx0a-001b2d01.pphosted.com with ESMTP id 2rft2r0pmb-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 26 Mar 2019 19:31:26 -0400 Received: from localhost by e12.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 26 Mar 2019 23:31:25 -0000 Received: from b01cxnp23032.gho.pok.ibm.com (9.57.198.27) by e12.ny.us.ibm.com (146.89.104.199) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 26 Mar 2019 23:31:19 -0000 Received: from b01ledav003.gho.pok.ibm.com (b01ledav003.gho.pok.ibm.com [9.57.199.108]) by b01cxnp23032.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x2QNVIwx24838182 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 26 Mar 2019 23:31:18 GMT Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 682A6B2068; Tue, 26 Mar 2019 23:31:18 +0000 (GMT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 48EBEB205F; Tue, 26 Mar 2019 23:31:18 +0000 (GMT) Received: from paulmck-ThinkPad-W541 (unknown [9.70.82.188]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTP; Tue, 26 Mar 2019 23:31:18 +0000 (GMT) Received: by paulmck-ThinkPad-W541 (Postfix, from userid 1000) id 6B2D516C60F3; Tue, 26 Mar 2019 16:31:19 -0700 (PDT) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, 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, joel@joelfernandes.org, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 1/9] torture: Don't try to offline the last CPU Date: Tue, 26 Mar 2019 16:31:10 -0700 X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190326233054.GA21523@linux.ibm.com> References: <20190326233054.GA21523@linux.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 19032623-0060-0000-0000-0000032274D1 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010820; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000282; SDB=6.01180138; UDB=6.00617576; IPR=6.00960854; MB=3.00026170; MTD=3.00000008; XFM=3.00000015; UTC=2019-03-26 23:31:23 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19032623-0061-0000-0000-000048BCD656 Message-Id: <20190326233118.23057-1-paulmck@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-03-26_15:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=13 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1903260158 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If there is only one online CPU, it doesn't make sense to try to offline it, as any such attempt is guaranteed to fail. This commit therefore check for this condition and refuses to attempt the nonsensical. Reported-by: Su Yue Signed-off-by: Paul E. McKenney Tested-By: Su Yue --- kernel/torture.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/torture.c b/kernel/torture.c index 8faa1a9aaeb9..17b2be9bde12 100644 --- a/kernel/torture.c +++ b/kernel/torture.c @@ -88,6 +88,8 @@ bool torture_offline(int cpu, long *n_offl_attempts, long *n_offl_successes, if (!cpu_online(cpu) || !cpu_is_hotpluggable(cpu)) return false; + if (num_online_cpus() <= 1) + return false; /* Can't offline the last CPU. */ if (verbose > 1) pr_alert("%s" TORTURE_FLAG -- 2.17.1