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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4C77AC433EF for ; Tue, 3 May 2022 17:58:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240822AbiECSBj (ORCPT ); Tue, 3 May 2022 14:01:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52488 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235852AbiECSBg (ORCPT ); Tue, 3 May 2022 14:01:36 -0400 Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F15663E0F1; Tue, 3 May 2022 10:58:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:From: References:Cc:To:Subject:MIME-Version:Date:Message-ID:Sender:Reply-To: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=V5OlIrQZACaQuAvW/eyS6B/1Zwik+ew1I16AuySJnIg=; b=gjAznZuoR4/m9kKzzhqzuGrpkT xtMc6cJN1cBQNuGvg6XyrPFTI1ixzsXC2Qdeh+HpywC/rv8GnlBjcukr7ohfRrQ9c8Vv3g1C+degf BKLK1MQn4ihq1pQ2tLJ4K6bqakBNB70xc08nkdXZEPCNZh6tlfswNgMdLLmr3btmvO+ASGsTB1McO bjtFx1IEqa+FJgHwAOYextuGE9H3QAozC9Ow4n5OqOMhRYX1e/PE6FhaxFfCh6NihoHwyZzrtpHli GlpKhk1VLnB8Ef855kd7QLHnrR7/smJu3dr6Yo1GdqpDjEKpnWDlt7/NfiaCRZ690xo8EgxQrZVRx GY9vS48w==; Received: from [179.113.53.197] (helo=[192.168.1.60]) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_128_GCM:128) (Exim) id 1nlwlp-0009Ge-E7; Tue, 03 May 2022 19:57:09 +0200 Message-ID: Date: Tue, 3 May 2022 14:56:27 -0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH 19/30] panic: Add the panic hypervisor notifier list Content-Language: en-US To: "Michael Kelley (LINUX)" , "akpm@linux-foundation.org" , "bhe@redhat.com" , "pmladek@suse.com" , "kexec@lists.infradead.org" Cc: "linux-kernel@vger.kernel.org" , "bcm-kernel-feedback-list@broadcom.com" , "linuxppc-dev@lists.ozlabs.org" , "linux-alpha@vger.kernel.org" , "linux-edac@vger.kernel.org" , "linux-hyperv@vger.kernel.org" , "linux-leds@vger.kernel.org" , "linux-mips@vger.kernel.org" , "linux-parisc@vger.kernel.org" , "linux-pm@vger.kernel.org" , "linux-remoteproc@vger.kernel.org" , "linux-s390@vger.kernel.org" , "linux-tegra@vger.kernel.org" , "linux-um@lists.infradead.org" , "linux-xtensa@linux-xtensa.org" , "netdev@vger.kernel.org" , "openipmi-developer@lists.sourceforge.net" , "rcu@vger.kernel.org" , "sparclinux@vger.kernel.org" , "xen-devel@lists.xenproject.org" , "x86@kernel.org" , "kernel-dev@igalia.com" , "kernel@gpiccoli.net" , "halves@canonical.com" , "fabiomirmar@gmail.com" , "alejandro.j.jimenez@oracle.com" , "andriy.shevchenko@linux.intel.com" , "arnd@arndb.de" , "bp@alien8.de" , "corbet@lwn.net" , "d.hatayama@jp.fujitsu.com" , "dave.hansen@linux.intel.com" , "dyoung@redhat.com" , "feng.tang@intel.com" , "gregkh@linuxfoundation.org" , "hidehiro.kawai.ez@hitachi.com" , "jgross@suse.com" , "john.ogness@linutronix.de" , "keescook@chromium.org" , "luto@kernel.org" , "mhiramat@kernel.org" , "mingo@redhat.com" , "paulmck@kernel.org" , "peterz@infradead.org" , "rostedt@goodmis.org" , "senozhatsky@chromium.org" , "stern@rowland.harvard.edu" , "tglx@linutronix.de" , "vgoyal@redhat.com" , vkuznets , "will@kernel.org" , Alexander Gordeev , Andrea Parri , Ard Biesheuvel , Benjamin Herrenschmidt , Brian Norris , Christian Borntraeger , Christophe JAILLET , David Gow , "David S. Miller" , Dexuan Cui , Doug Berger , Evan Green , Florian Fainelli , Haiyang Zhang , Hari Bathini , Heiko Carstens , Julius Werner , Justin Chen , KY Srinivasan , Lee Jones , Markus Mayer , Michael Ellerman , Mihai Carabas , Nicholas Piggin , Paul Mackerras , Pavel Machek , Scott Branden , Sebastian Reichel , Shile Zhang , Stephen Hemminger , Sven Schnelle , Thomas Bogendoerfer , Tianyu Lan , Vasily Gorbik , Wang ShaoBo , Wei Liu , zhenwei pi References: <20220427224924.592546-1-gpiccoli@igalia.com> <20220427224924.592546-20-gpiccoli@igalia.com> <0147d038-571b-0802-c210-ccd4d52cd5dd@igalia.com> From: "Guilherme G. Piccoli" In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 03/05/2022 14:44, Michael Kelley (LINUX) wrote: > [...] >> >> Hi Michael, thanks for your feedback! I agree that your idea could work, >> but...there is one downside: imagine the kmsg_dump() approach is not set >> in some Hyper-V guest, then we would rely in the regular notification >> mechanism [hv_die_panic_notify_crash()], right? >> But...you want then to run this notifier in the informational list, >> which...won't execute *by default* before kdump if no kmsg_dump() is >> set. So, this logic is convoluted when you mix it with the default level >> concept + kdump. > > Yes, you are right. But to me that speaks as much to the linkage > between the informational list and kmsg_dump() being the core > problem. But as I described in my reply to Patch 24, I can live with > the linkage as-is. Thanks for the feedback Michael! > [...] >> I feel the panic notification mechanism does really fit with a >> hypervisor list, it's a good match with the nature of the list, which >> aims at informing the panic notification to the hypervisor/FW. >> Of course we can modify it if you prefer...but please take into account >> the kdump case and how it complicates the logic. > > I agree that the runtime effect of one list vs. the other is nil. The > code works and can stay as you written it. > > I was trying to align from a conceptual standpoint. It was a bit > unexpected that one path would be on the hypervisor list, and the > other path effectively on the informational list. When I see > conceptual mismatches like that, I tend to want to understand why, > and if there is something more fundamental that is out-of-whack. > Totally agree with you here, I am like that as well - try to really understand the details, this is very important specially in this patch set, since it's a refactor and affects every user of the notifiers infrastructure. Again, just to double-say it: feel free to suggest any change for the Hyper-V portion (might as well for any patch in the series, indeed) - you and the other Hyper-V maintainers own this code and I'd be glad to align with your needs, you are honor citizens in the panic notifiers area, being one the most heavy users for that =) Cheers, Guilherme