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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS 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 1A5D1C43219 for ; Mon, 29 Apr 2019 05:55:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E54292075E for ; Mon, 29 Apr 2019 05:55:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727363AbfD2Fz3 (ORCPT ); Mon, 29 Apr 2019 01:55:29 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:58558 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726979AbfD2Fz3 (ORCPT ); Mon, 29 Apr 2019 01:55:29 -0400 Received: from pps.filterd (m0098409.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x3T5rWnt070566 for ; Mon, 29 Apr 2019 01:55:28 -0400 Received: from e06smtp02.uk.ibm.com (e06smtp02.uk.ibm.com [195.75.94.98]) by mx0a-001b2d01.pphosted.com with ESMTP id 2s5tjwht0b-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Mon, 29 Apr 2019 01:55:27 -0400 Received: from localhost by e06smtp02.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, 29 Apr 2019 06:55:23 +0100 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x3T5tM5N63176736 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 29 Apr 2019 05:55:22 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 161B44C046; Mon, 29 Apr 2019 05:55:22 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C33C24C044; Mon, 29 Apr 2019 05:55:21 +0000 (GMT) Received: from osiris (unknown [9.152.212.21]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Mon, 29 Apr 2019 05:55:21 +0000 (GMT) Date: Mon, 29 Apr 2019 07:55:20 +0200 From: Heiko Carstens To: Prarit Bhargava Cc: Jessica Yu , linux-next@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, Cathy Avery Subject: Re: [-next] system hangs likely due to "modules: Only return -EEXIST for modules that have finished loading" References: <20190426130736.GB8646@osiris> <20190426150741.GD8646@osiris> <20190426160956.GA3827@linux-8ccs> <2e047a7e-bf08-be8c-bdd0-429464fa133d@redhat.com> <52c293e9-ddfa-426a-a8f1-2106e250e78d@redhat.com> <20190427102440.GA28889@osiris> <6a69074a-e913-3b67-feef-9b62a7400f8a@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6a69074a-e913-3b67-feef-9b62a7400f8a@redhat.com> X-TM-AS-GCONF: 00 x-cbid: 19042905-0008-0000-0000-000002E15202 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19042905-0009-0000-0000-0000224DB46F Message-Id: <20190429055520.GA3665@osiris> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-04-29_03:,, 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 mlxscore=0 impostorscore=0 mlxlogscore=911 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904290045 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Apr 27, 2019 at 06:42:51AM -0400, Prarit Bhargava wrote: > On 4/27/19 6:24 AM, Heiko Carstens wrote: > > > > > diff --git a/kernel/module.c b/kernel/module.c > > index 410eeb7e4f1d..48748cfec991 100644 > > --- a/kernel/module.c > > +++ b/kernel/module.c > > @@ -3585,6 +3585,7 @@ again: > > finished_loading(mod->name)); > > if (err) > > goto out_unlocked; > > + cond_resched(); > Heiko, I'm testing on 2-cpu systems which appear to show the problem ~10% of the > time. On another system I backed out my original patch to set a baseline, and > noticed that occasionally the time to boot the system doubles from ~4 seconds to > 9 seconds. Is this something you're also concerned with? This _could_ be an issue, since I see the problem much more likely to happen on systems with many devices (where many means only something like 10 block devices). As far as I can tell it looks like systemd/udevd tries to modprobe at the s390-trng module for each(!) device. I have no idea why it is doing that... however given that (failed) module handling now sometimes takes more time, this might become a real issue on system with several 1000s of block devices, which is a realistic scenario at least on s390.