From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from userp2120.oracle.com ([156.151.31.85]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kKSF1-0007h4-GN for kexec@lists.infradead.org; Mon, 21 Sep 2020 20:16:52 +0000 Date: Mon, 21 Sep 2020 16:18:12 -0400 From: Konrad Rzeszutek Wilk Subject: Re: [PATCH] Only allow to set crash_kexec_post_notifiers on boot time Message-ID: <20200921201811.GB3437@char.us.oracle.com> References: <20200918032546.GA4180@dhcp-128-65.nay.redhat.com> <20200918174743.0994c59f058451948837dcb6@linux-foundation.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200918174743.0994c59f058451948837dcb6@linux-foundation.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Andrew Morton Cc: bhe@redhat.com, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, Eric Biederman , Boris Ostrovsky , Eric DeVolder , Dave Young On Fri, Sep 18, 2020 at 05:47:43PM -0700, Andrew Morton wrote: > On Fri, 18 Sep 2020 11:25:46 +0800 Dave Young wrote: > > > crash_kexec_post_notifiers enables running various panic notifier > > before kdump kernel booting. This increases risks of kdump failure. > > It is well documented in kernel-parameters.txt. We do not suggest > > people to enable it together with kdump unless he/she is really sure. > > This is also not suggested to be enabled by default when users are > > not aware in distributions. > > > > But unfortunately it is enabled by default in systemd, see below > > discussions in a systemd report, we can not convince systemd to change > > it: > > https://github.com/systemd/systemd/issues/16661 > > > > Actually we have got reports about kdump kernel hangs in both s390x > > and powerpcle cases caused by the systemd change, also some x86 cases > > could also be caused by the same (although that is in Hyper-V code > > instead of systemd, that need to be addressed separately). Perhaps it may be better to fix the issus on s390x and PowerPC as well? > > > > Thus to avoid the auto enablement here just disable the param writable > > permission in sysfs. > > > > Well. I don't think this is at all a desirable way of resolving a > disagreement with the systemd developers > > At the above github address I'm seeing "ryncsn added a commit to > ryncsn/systemd that referenced this issue 9 days ago", "pstore: don't > enable crash_kexec_post_notifiers by default". So didn't that address > the issue? It does in systemd, but there is a strong interest in making this on by default. _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec 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=-11.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,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 AD0E6C4363C for ; Mon, 21 Sep 2020 20:16:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5469221789 for ; Mon, 21 Sep 2020 20:16:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="ipUuetlu" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726480AbgIUUQ4 (ORCPT ); Mon, 21 Sep 2020 16:16:56 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:50978 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726435AbgIUUQz (ORCPT ); Mon, 21 Sep 2020 16:16:55 -0400 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 08LKEfia194172; Mon, 21 Sep 2020 20:16:47 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2020-01-29; bh=Mt+aUTyxqBIgxXWtK4cmF7Dnc9mlrKM0yEoLKj0+Spk=; b=ipUuetluqGLj4x4D4uofwZGPTB6fLoOS954lafOzhq3CR8/MgH6+UPa9UqxoRPvh/WgS 2g8Nvzpph+w6QoqQfVBCMaB33k4i1j6j0rrXV4mbSp8Eud2aTyeUiVA6iEm97UWF8lcK vo3KMzc42bBwIFUo60p4D+oXS6VQSIdT4af2qDil01vmdclFxlHFNh1+Eau5Nx8NCM8v 7e295FyA/vQ/by6m9alI1IX5CJGnBAPHO6PYsIPBwAONfEYST2mwFPUlbeHAzfPif/yh B/UZ7br8ka7IsZfE2cYBD6fqx6RWq+gqMBONsMxmAHSvGLtk+j/0D++pAxVdp2A9M5iG Ow== Received: from aserp3020.oracle.com (aserp3020.oracle.com [141.146.126.70]) by userp2120.oracle.com with ESMTP id 33ndnu8nk7-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 21 Sep 2020 20:16:47 +0000 Received: from pps.filterd (aserp3020.oracle.com [127.0.0.1]) by aserp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 08LKFmOR190268; Mon, 21 Sep 2020 20:16:46 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by aserp3020.oracle.com with ESMTP id 33nuw1ssb5-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 21 Sep 2020 20:16:46 +0000 Received: from abhmp0012.oracle.com (abhmp0012.oracle.com [141.146.116.18]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 08LKGhMU001821; Mon, 21 Sep 2020 20:16:44 GMT Received: from char.us.oracle.com (/10.152.32.25) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 21 Sep 2020 13:16:43 -0700 Received: by char.us.oracle.com (Postfix, from userid 1000) id 34DB86A012C; Mon, 21 Sep 2020 16:18:12 -0400 (EDT) Date: Mon, 21 Sep 2020 16:18:12 -0400 From: Konrad Rzeszutek Wilk To: Andrew Morton Cc: Dave Young , bhe@redhat.com, Eric Biederman , linux-kernel@vger.kernel.org, kexec@lists.infradead.org, Eric DeVolder , Boris Ostrovsky Subject: Re: [PATCH] Only allow to set crash_kexec_post_notifiers on boot time Message-ID: <20200921201811.GB3437@char.us.oracle.com> References: <20200918032546.GA4180@dhcp-128-65.nay.redhat.com> <20200918174743.0994c59f058451948837dcb6@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200918174743.0994c59f058451948837dcb6@linux-foundation.org> User-Agent: Mutt/1.9.1 (2017-09-22) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9751 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 phishscore=0 malwarescore=0 mlxscore=0 suspectscore=0 adultscore=0 mlxlogscore=999 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009210148 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9751 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 lowpriorityscore=0 phishscore=0 adultscore=0 suspectscore=0 bulkscore=0 clxscore=1011 impostorscore=0 mlxlogscore=999 mlxscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009210148 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 18, 2020 at 05:47:43PM -0700, Andrew Morton wrote: > On Fri, 18 Sep 2020 11:25:46 +0800 Dave Young wrote: > > > crash_kexec_post_notifiers enables running various panic notifier > > before kdump kernel booting. This increases risks of kdump failure. > > It is well documented in kernel-parameters.txt. We do not suggest > > people to enable it together with kdump unless he/she is really sure. > > This is also not suggested to be enabled by default when users are > > not aware in distributions. > > > > But unfortunately it is enabled by default in systemd, see below > > discussions in a systemd report, we can not convince systemd to change > > it: > > https://github.com/systemd/systemd/issues/16661 > > > > Actually we have got reports about kdump kernel hangs in both s390x > > and powerpcle cases caused by the systemd change, also some x86 cases > > could also be caused by the same (although that is in Hyper-V code > > instead of systemd, that need to be addressed separately). Perhaps it may be better to fix the issus on s390x and PowerPC as well? > > > > Thus to avoid the auto enablement here just disable the param writable > > permission in sysfs. > > > > Well. I don't think this is at all a desirable way of resolving a > disagreement with the systemd developers > > At the above github address I'm seeing "ryncsn added a commit to > ryncsn/systemd that referenced this issue 9 days ago", "pstore: don't > enable crash_kexec_post_notifiers by default". So didn't that address > the issue? It does in systemd, but there is a strong interest in making this on by default.