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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 A2801C352AA for ; Wed, 2 Oct 2019 07:40:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6D7F421D80 for ; Wed, 2 Oct 2019 07:40:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726931AbfJBHkG (ORCPT ); Wed, 2 Oct 2019 03:40:06 -0400 Received: from mx2.suse.de ([195.135.220.15]:60654 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725852AbfJBHkG (ORCPT ); Wed, 2 Oct 2019 03:40:06 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 6A720ACFE; Wed, 2 Oct 2019 07:40:04 +0000 (UTC) Subject: Re: [Xen-devel] [PATCH] x86/xen: Return from panic notifier To: Boris Ostrovsky Cc: xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, james@dingwall.me.uk, Juergen Gross References: <20191001151633.1659-1-boris.ostrovsky@oracle.com> From: Jan Beulich Message-ID: <9b3f955c-ad76-601f-2b58-fa9dc4608c72@suse.com> Date: Wed, 2 Oct 2019 09:40:11 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20191001151633.1659-1-boris.ostrovsky@oracle.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01.10.2019 17:16, Boris Ostrovsky wrote: > Currently execution of panic() continues until Xen's panic notifier > (xen_panic_event()) is called at which point we make a hypercall that > never returns. > > This means that any notifier that is supposed to be called later as > well as significant part of panic() code (such as pstore writes from > kmsg_dump()) is never executed. Back at the time when this was introduced into the XenoLinux tree, I think this behavior was intentional for at least DomU-s. I wonder whether you wouldn't want your change to further distinguish Dom0 and DomU behavior. > There is no reason for xen_panic_event() to be this last point in > execution since panic()'s emergency_restart() will call into > xen_emergency_restart() from where we can perform our hypercall. Did you consider, as an alternative, to lower the notifier's priority? Jan