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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 C5055C3F2CD for ; Mon, 2 Mar 2020 18:17:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9EC2520836 for ; Mon, 2 Mar 2020 18:17:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727465AbgCBSRi (ORCPT ); Mon, 2 Mar 2020 13:17:38 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:39630 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726451AbgCBSRi (ORCPT ); Mon, 2 Mar 2020 13:17:38 -0500 Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 022IFJsX057560 for ; Mon, 2 Mar 2020 13:17:36 -0500 Received: from e06smtp05.uk.ibm.com (e06smtp05.uk.ibm.com [195.75.94.101]) by mx0b-001b2d01.pphosted.com with ESMTP id 2yfjf46n3m-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Mon, 02 Mar 2020 13:17:36 -0500 Received: from localhost by e06smtp05.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Mon, 2 Mar 2020 18:17:31 -0000 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 022IHUU064094304 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 2 Mar 2020 18:17:30 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8A4B8A4051; Mon, 2 Mar 2020 18:17:30 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 41650A4053; Mon, 2 Mar 2020 18:17:29 +0000 (GMT) Received: from oc7455500831.ibm.com (unknown [9.145.167.221]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 2 Mar 2020 18:17:29 +0000 (GMT) Subject: Re: 5.6-rc3: WARNING: CPU: 48 PID: 17435 at kernel/sched/fair.c:380 enqueue_task_fair+0x328/0x440 From: Christian Borntraeger To: Vincent Guittot Cc: Ingo Molnar , Peter Zijlstra , "linux-kernel@vger.kernel.org" References: <1a607a98-f12a-77bd-2062-c3e599614331@de.ibm.com> <20200228163545.GA18662@vingu-book> Autocrypt: addr=borntraeger@de.ibm.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 20030218-0020-0000-0000-000003AFB01A X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 20030218-0021-0000-0000-00002207DC65 Message-Id: <49a2ebb7-c80b-9e2b-4482-7f9ff938417d@de.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.572 definitions=2020-03-02_07:2020-03-02,2020-03-02 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 suspectscore=0 malwarescore=0 bulkscore=0 phishscore=0 mlxscore=0 mlxlogscore=999 clxscore=1015 impostorscore=0 spamscore=0 adultscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2003020119 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02.03.20 12:16, Christian Borntraeger wrote: > > > On 28.02.20 17:35, Vincent Guittot wrote: >> Le vendredi 28 févr. 2020 à 16:42:27 (+0100), Christian Borntraeger a écrit : >>> >>> >>> On 28.02.20 16:37, Vincent Guittot wrote: >>>> On Fri, 28 Feb 2020 at 16:08, Christian Borntraeger >>>> wrote: >>>>> >>>>> Also happened with 5.4: >>>>> Seems that I just happen to have an interesting test workload/system size interaction >>>>> on a newly installed system that triggers this. >>>> >>>> you will probably go back to 5.1 which is the version where we put >>>> back the deletion of unused cfs_rq from the list which can trigger the >>>> warning: >>>> commit 039ae8bcf7a5 : (Fix O(nr_cgroups) in the load balancing path) >>>> >>>> AFAICT, we haven't changed this since >>> >>> So you do know what is the problem? If not is there any debug option or >>> patch that I could apply to give you more information? >> >> No I don't know what is happening. Your test probably goes through an unexpected path >> >> Would it be difficult for me to reproduce your test env ? > > Not sure. Its a 32CPU (SMT2 -> 64) host. I have about 10 KVM guests running doing different > things. > >> >> There is an optimization in the code which could generate problem if assumption is not >> true. Could you try the patch below ? >> >> --- >> kernel/sched/fair.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c >> index 3c8a379c357e..beb773c23e7d 100644 >> --- a/kernel/sched/fair.c >> +++ b/kernel/sched/fair.c >> @@ -4035,8 +4035,8 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) >> __enqueue_entity(cfs_rq, se); >> se->on_rq = 1; >> >> + list_add_leaf_cfs_rq(cfs_rq); >> if (cfs_rq->nr_running == 1) { >> - list_add_leaf_cfs_rq(cfs_rq); >> check_enqueue_throttle(cfs_rq); >> } >> } > > Now running for 3 hours. I have not seen the issue yet. I can tell tomorrow if this fixes > the issue. Still running fine. I can tell for sure tomorrow, but I have the impression that this makes the WARN_ON go away.