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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL 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 2944AC43441 for ; Thu, 22 Nov 2018 04:57:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DBD1120864 for ; Thu, 22 Nov 2018 04:57:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=cisco.com header.i=@cisco.com header.b="gPC+nLQ5" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DBD1120864 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=cisco.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404556AbeKVPfK (ORCPT ); Thu, 22 Nov 2018 10:35:10 -0500 Received: from rcdn-iport-3.cisco.com ([173.37.86.74]:10109 "EHLO rcdn-iport-3.cisco.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732146AbeKVPfK (ORCPT ); Thu, 22 Nov 2018 10:35:10 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=cisco.com; i=@cisco.com; l=2824; q=dns/txt; s=iport; t=1542862651; x=1544072251; h=subject:to:cc:references:from:message-id:date: mime-version:in-reply-to:content-transfer-encoding; bh=EogIDfV15YxKr2BXXdqnF6omuQ2/TzVu/7ZV0Brqjlw=; b=gPC+nLQ572ajJLQiE4yxkG50bjtAzQQbHyK6nNrwJ9aRqqOK9lb8O3Rw TLfP5HfZbuebO+C9P/moch4yO28E0uwebLpiQnaq94ptrv9rMnLwo502O AhL3looZY+ch996/ffcoHy0GqJQ2wnhu2pWb2+OdcwydRG5CNr6vIBpOh g=; X-IronPort-AV: E=Sophos;i="5.56,264,1539648000"; d="scan'208";a="476454414" Received: from rcdn-core-8.cisco.com ([173.37.93.144]) by rcdn-iport-3.cisco.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 22 Nov 2018 04:57:31 +0000 Received: from [10.24.99.63] ([10.24.99.63]) by rcdn-core-8.cisco.com (8.15.2/8.15.2) with ESMTP id wAM4vSVd019125; Thu, 22 Nov 2018 04:57:28 GMT Subject: Re: [PATCH v5] kernel/signal: Signal-based pre-coredump notification To: Andrew Morton Cc: Oleg Nesterov , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Peter Zijlstra , Arnd Bergmann , "Eric W. Biederman" , Khalid Aziz , Kate Stewart , Helge Deller , Greg Kroah-Hartman , Al Viro , Christian Brauner , Catalin Marinas , Will Deacon , Dave Martin , Mauro Carvalho Chehab , Michal Hocko , Rik van Riel , "Kirill A. Shutemov" , Roman Gushchin , Marcos Paulo de Souza , Dominik Brodowski , Cyrill Gorcunov , Yang Shi , Jann Horn , Kees Cook , x86@kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, "Victor Kamensky (kamensky)" , xe-linux-external@cisco.com, Stefan Strogin , Enke Chen References: <458c04d8-d189-4a26-729a-bb1d1d751534@cisco.com> <7741efa7-a3f8-62a1-ba52-613883164643@cisco.com> <84460a77-a111-404e-4bad-88104a6e246e@cisco.com> <20181026082812.GA10581@redhat.com> <21f678a8-4001-df36-c26e-e96cf203b1b1@cisco.com> <20181029111804.GA24820@redhat.com> <0c197608-3b7e-ffd1-8943-801a60beb917@cisco.com> <20181030164628.GD7643@redhat.com> <20181121163711.2c00316784d221eb1750edb0@linux-foundation.org> <20181121173341.707a0a869bf16b85f09d75b5@linux-foundation.org> From: Enke Chen Message-ID: <08366d06-9f47-b80e-3662-a84c5107be89@cisco.com> Date: Wed, 21 Nov 2018 20:57:31 -0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20181121173341.707a0a869bf16b85f09d75b5@linux-foundation.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Auto-Response-Suppress: DR, OOF, AutoReply X-Outbound-SMTP-Client: 10.24.99.63, [10.24.99.63] X-Outbound-Node: rcdn-core-8.cisco.com Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Andrew: As suggested, I will post them as a patch series (with the same version v5): [PATCH v5 1/2] kernel/signal: Signal-based pre-coredump notification [PATCH v5 2/2] selftests/prctl: selftest for pre-coredump signal notification I have a diff for the manpage as well. I guess that it should be submitted separately from the code. Thanks. -- Enke On 11/21/18 5:33 PM, Andrew Morton wrote: > On Wed, 21 Nov 2018 17:09:50 -0800 Enke Chen wrote: > >> Hi, Andrew: >> >> On 11/21/18 4:37 PM, Andrew Morton wrote: >>> On Tue, 30 Oct 2018 17:46:29 +0100 Oleg Nesterov wrote: >>> >>>> On 10/29, Enke Chen wrote: >>>>> >>>>> Reviewed-by: Oleg Nesterov >>>> >>>> Hmm. I didn't say this ;) >>>> >>>> But OK, feel free to keep this tag. >>>> >>>> I do not like this feauture. >>> >>> Why is that? >>> >>>> But I see no technical problems in this version >>>> and I never pretented I understand the user-space needs, so I won't argue. >>> >>> The changelog appears to spell this all out quite well? Unusually >>> well, in my experience ;) >> >> I also followed up with a little more explanation in the email thread on >> 10/30/2018: >> >> --- >> As I explained earlier, the primary application is in the area of network >> high-availability / non-stop-forwarding where early fault notification and >> early action can help maintain BFD sessions and thus avoid unnecessary >> disruption to forwarding while the control-plane is recovering. >> --- >> >> BTW, I probably should have pointed out this earlier: >> >> BFD stands for "RFC 5880: Bi-directional forwarding detection". > > I saw that. My point is that your above followup wasn't necessary - > the changelog is clear! > >>> >>> - As it's a linux-specific feature, a test under >>> tools/testing/selftests would be appropriate. I don't know how much >>> that work will be. >> >> The selftest code was submitted on 10/25/2018: >> >> [PATCH] selftests/prctl: selftest for pre-coredump signal notification > > OK, please prepare these as a patch series. > >>> Do we have other linux-specific signal extensions which could piggyback onto that? >> >> No. There are enough existing signals that an application can choose for this >> purpose, such as SIGUSR1, SIGUSR1, and any of the RT signals. >> > > My point is that if we have previously added any linux-specific signal > expensions then your selftest patch would be an appropriate place where > we could add tests for those features. I'm not saying that you should > add such tests at this time, but please do prepare the selftest as a > thing which tests linux-specific signal extensions in general, not as a > thing which tests pre-coredump signals only. >