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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9F11EC433F5 for ; Fri, 5 Nov 2021 10:48:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 718F9610A8 for ; Fri, 5 Nov 2021 10:48:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231386AbhKEKvO (ORCPT ); Fri, 5 Nov 2021 06:51:14 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:55538 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231341AbhKEKvN (ORCPT ); Fri, 5 Nov 2021 06:51:13 -0400 Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 1A58Ci13017548; Fri, 5 Nov 2021 10:48:29 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=message-id : date : mime-version : subject : to : cc : references : from : in-reply-to : content-type : content-transfer-encoding; s=pp1; bh=YswT44oYLJ1/YWPku653gcH5Xu3poC4JGNqXkOaeKlQ=; b=n8jauLuUDiVdlUeGN1zQ7G15jLnarnMU4JP5sKRsSIccm5XojEpSvQgtyidXv6Z7kAN8 dCOTA2KBVrVVjyvYObHtBZwWlOxq9NhZsdeMEIPlRFPmrwRTCkFxVp1XFUhYVN+nSm57 1l/pLFCWiorQe74SlRv0pDwXz3AWV3m//HULOY8yfG8tyaWZ8GuqhDShNmTtrsYpLfPK r1djwo9ol/OKOYjUFP2gtDtd5fAVHUMeN7xCngO3pznRDAm9iiwFd15h+NpiFK1xceul pr7o3sEPlq0jRDnGoP54/yQCUHb2O2DOttAf08DePV8VMadKmxL9283p0cQzOtqLTcID 8g== Received: from ppma02fra.de.ibm.com (47.49.7a9f.ip4.static.sl-reverse.com [159.122.73.71]) by mx0a-001b2d01.pphosted.com with ESMTP id 3c4xuhw0pg-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 05 Nov 2021 10:48:29 +0000 Received: from pps.filterd (ppma02fra.de.ibm.com [127.0.0.1]) by ppma02fra.de.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 1A5AmE9j012139; Fri, 5 Nov 2021 10:48:27 GMT Received: from b06cxnps4076.portsmouth.uk.ibm.com (d06relay13.portsmouth.uk.ibm.com [9.149.109.198]) by ppma02fra.de.ibm.com with ESMTP id 3c4t4tba6g-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 05 Nov 2021 10:48:26 +0000 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 1A5AmOw259506958 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 5 Nov 2021 10:48:24 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4925E4C05C; Fri, 5 Nov 2021 10:48:24 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D26E24C04E; Fri, 5 Nov 2021 10:48:23 +0000 (GMT) Received: from [9.171.36.217] (unknown [9.171.36.217]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 5 Nov 2021 10:48:23 +0000 (GMT) Message-ID: <9784062e-df82-c6f0-28a2-6bdb2ea9d874@linux.ibm.com> Date: Fri, 5 Nov 2021 11:48:23 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: REGRESSION: relocating a Debian/bullseye guest is losing network connection Content-Language: en-US To: Martin Grimm , Waldemar Brodkorb , linux-s390@vger.kernel.org Cc: Karsten Graul References: <933ba5bc-a3eb-a67b-26a0-ab19a0ec787c@linux.ibm.com> <0869a8d7-3b15-bad0-f42e-915b28730c7b@itzbund.de> From: Julian Wiedmann In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 5E5n2Ypt_lFNOt3Mp5wWRMS7NevvE3fy X-Proofpoint-ORIG-GUID: 5E5n2Ypt_lFNOt3Mp5wWRMS7NevvE3fy X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.0.607.475 definitions=2021-11-05_01,2021-11-03_01,2020-04-07_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 suspectscore=0 bulkscore=0 clxscore=1015 malwarescore=0 spamscore=0 lowpriorityscore=0 phishscore=0 adultscore=0 impostorscore=0 mlxlogscore=999 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2111050062 Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On 04.11.21 12:53, Martin Grimm wrote: > Am 02.11.21 um 10:03 schrieb Julian Wiedmann: >> On 29.10.21 15:52, Martin Grimm wrote: >>> Hi, >>> >>> I'm a collegue of Waldemar and I'd like to respond on his behalf. >>> [...] >>>>> All manually added routing information will be lost anyway. >>>>> >>>>> And I might not imagine what happens to any firewall connection >>>>> tables or ipvs connection tracking information in case of a Live >>>>> Guest Relocation. >>>>> >>>>> So is there any kernel level solution for this you can think of? >>>>> >>>> >>>> As discussed off-list, a plain "ip link set dev eth0 down" gives you >>>> the same result. Hence I would recommend to improve your configuration, >>>> so that the needed routes are restored when the interface comes up >>>> again. >>>> > Your proposed test with "ip link set dev eth0 down && ip link set dev eth0 up" > also kills all static routing information on a regular setup RHEL 7.9 system. > So maybe it shouldn't be taken for granted that server systems with static > network configuration recover from such outages automatically. > It's taken for granted in a sense that even old code was calling dev_close() when setting the device offline (ie. 0 > /sys/devices/qeth/x.x.xxxx/offline) for certain config changes. So the implicit need to preserve such user-side config was there, even when you didn't encounter it previously. >>> >>> I'd like to disagree. From my point of view the state after a "real" >>> device outage is irrelevant regarding "Live Guest Relocation". >>> >>> LGR is meant to provide seamless migration of zLinux guests from >>> one z/VM to the other during production workloads. >>> So the linux guest has to be in exactly the same state after migration >>> to the new z/VM as it was before. That also includes IMHO dynamic >>> routes added e.g. by a service like keepalived or even by hand. >>> >> >> Sorry, unfortunately that doesn't match up with reality. LGR still requires >> a full re-establish of the HW context (ie. you're losing whatever packets >> are in the RX and TX queues at that moment), and then needs activity by the >> Linux network core to establish itself in the new network environment. >> >> Bypassing the corresponding NETDEV_UP event etc (as the old code did) means >> that we eg. don't get fresh GARPs, and traffic is then forwarded to stale >> switch ports. >> >> So no, we can't go back to the mode of doing things behind the network >> stack's back. It sort-of worked for a while, but we reached its limits. >> > > Sorry to hear that :-( > For us as customers (our POV) that means LGR that worked for years without > any noticable problem for hundreds of linux guests with thousands of successful > relocations isn't usable anymore or only with great care. I wouldn't want to fully demotivate you. If there are ways to bypass such a "fake" admin-down via dev_close() but still 1. close & open the device in a sane manner so that all the relevant driver-level callbacks are fenced off, and 2. have the network code do all the necessary work on stop & open to harmonize us with a potentially new network environment, stacked devices etc (based on eg. linkwatch's NETDEV_CHANGE, netdev_state_change(), netdev_notify_peers(), ...) then I'd consider that a very viable solution. What we _can't_ do is re-implement that logic in the driver itself, and then just pray that we stay current with all subsequent changes in the stack's behaviour. > But perhaps this mailing list is not the right audience for customer problems > and we should address this via a PMR to focus on the interaction between z/VM > and Linux. > >>> Before Kernel v5 this was the observed behavior. >>> >>> Starting with Kernel v5 LGR now triggers a network outage that makes >>> it unusable for many kinds of production systems. >>> Before version 5 there where device failure and recovery messages >>> in the kernel log but the network configuration stayed intact. >>> >>> Just to be sure I compared this with the behavior of VMWare Live Migration >>> and there all dynamic routes stay in place as it was with LGR >>> before Kernel v5. Not a single error message in kernel log there. >>> >>> So if the new behavior is correct for a real device outage, maybe LGR >>> should be handled differently? >>> >>>>> Thanks for any advice and comments, >>>>> >>>>> best regards >>>>>    Waldemar >>>>> >>>> >>> >>> Greetings >>> Martin >> >