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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 9042FC04EB9 for ; Tue, 16 Oct 2018 00:34:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4F223208D9 for ; Tue, 16 Oct 2018 00:34:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4F223208D9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=vt.edu 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 S1727017AbeJPIVr (ORCPT ); Tue, 16 Oct 2018 04:21:47 -0400 Received: from outbound.smtp.vt.edu ([198.82.183.121]:50964 "EHLO omr1.cc.vt.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726946AbeJPIVr (ORCPT ); Tue, 16 Oct 2018 04:21:47 -0400 Received: from mr4.cc.vt.edu (mail.ipv6.vt.edu [IPv6:2607:b400:92:9:0:9d:8fcb:4116]) by omr1.cc.vt.edu (8.14.4/8.14.4) with ESMTP id w9G0Y6Au008822 for ; Mon, 15 Oct 2018 20:34:06 -0400 Received: from mail-qk1-f200.google.com (mail-qk1-f200.google.com [209.85.222.200]) by mr4.cc.vt.edu (8.14.7/8.14.7) with ESMTP id w9G0Y0np013781 for ; Mon, 15 Oct 2018 20:34:06 -0400 Received: by mail-qk1-f200.google.com with SMTP id d200-v6so21731729qkc.22 for ; Mon, 15 Oct 2018 17:34:06 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:to:cc:subject:in-reply-to:references :mime-version:content-transfer-encoding:date:message-id; bh=T1IRuDbS2RuhG5flVTa5ziE+5IjHXRnSsn0Uqbmzq/A=; b=nfSnX0Oh215iuo1WioXhNjxV3XhVAmQ3koMeNXOzxyJItgaIdvZrSbOukGvo9NKHmI xgce5M4Xa1TUr6fIG5866O+lpi7rwJ4icbsaLjZSwLpAB7MMBZtcNZiBnoy9ga3yPIsn com9kHn3jJC56VR8IAaYpoqp3zPFIyAMDJpIAMGrW0E6qpxxmGjrdMKSK3sh7L0CkaI1 52Z8DWtYxwe3ISnrVp0YDfy951Q5UM6MMEAhAGu3kb33CrcHROsPzYL5e9g/ppje0FPE WHhCgYaJ7phL/LQ8b6qucJ+aec+gdrLb3codxUmWjjeEyFo20IRqkg4UNjtRI6bMqYlQ 7bdw== X-Gm-Message-State: ABuFfogZDjtwTah39mRlNGnRh8H2veUgGLWCSd35YoNp2I4urXo6F2GP r1zpwTqSN+FFx3buTNCr505d7HDVwNBhmhHzaQyzdG21Xmeo0A2dmC3ScCpOsD8gTZRkm2fy0EH IB9pcEMGfmzpQpFKyJHq0SgmQglBooclZudw= X-Received: by 2002:aed:24c3:: with SMTP id u3-v6mr18035490qtc.230.1539650035280; Mon, 15 Oct 2018 17:33:55 -0700 (PDT) X-Google-Smtp-Source: ACcGV60g0DamtbSFjiqGgISXH9Z4Oo7CsrKCzQxaYdBNFwCzrum7m+AtUCVkoEXooaW5bldxK152fw== X-Received: by 2002:aed:24c3:: with SMTP id u3-v6mr18035473qtc.230.1539650034843; Mon, 15 Oct 2018 17:33:54 -0700 (PDT) Received: from turing-police.cc.vt.edu ([2607:b400:24:0:3d3c:680f:afbc:c585]) by smtp.gmail.com with ESMTPSA id n25-v6sm10637764qtf.14.2018.10.15.17.33.52 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 15 Oct 2018 17:33:53 -0700 (PDT) From: valdis.kletnieks@vt.edu X-Google-Original-From: Valdis.Kletnieks@vt.edu X-Mailer: exmh version 2.8.0 04/21/2017 with nmh-1.7+dev To: ebiederm@xmission.com (Eric W. Biederman) Cc: Enke Chen , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , x86@kernel.org, Peter Zijlstra , Arnd Bergmann , Khalid Aziz , Kate Stewart , Helge Deller , Greg Kroah-Hartman , Al Viro , Andrew Morton , 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 , Oleg Nesterov , Dominik Brodowski , Cyrill Gorcunov , Yang Shi , Jann Horn , Kees Cook , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, "Victor Kamensky \(kamensky\)" , xe-linux-external@cisco.com, Stefan Strogin Subject: Re: [PATCH] kernel/signal: Signal-based pre-coredump notification In-Reply-To: <87va62lri4.fsf@xmission.com> References: <87va62lri4.fsf@xmission.com> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="==_Exmh_1539650031_2195P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit Date: Mon, 15 Oct 2018 20:33:51 -0400 Message-ID: <5192.1539650031@turing-police.cc.vt.edu> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --==_Exmh_1539650031_2195P Content-Type: text/plain; charset=us-ascii On Mon, 15 Oct 2018 18:28:03 -0500, Eric W. Biederman said: > Enke Chen writes: > > > For simplicity and consistency, this patch provides an implementation > > for signal-based fault notification prior to the coredump of a child > > process. A new prctl command, PR_SET_PREDUMP_SIG, is defined that can > > be used by an application to express its interest and to specify the > > signal (SIGCHLD or SIGUSR1 or SIGUSR2) for such a notification. A new > > signal code (si_code), CLD_PREDUMP, is also defined for SIGCHLD. > > > > Background: > > > > As the coredump of a process may take time, in certain time-sensitive > > applications it is necessary for a parent process (e.g., a process > > manager) to be notified of a child's imminent death before the coredump > > so that the parent process can act sooner, such as re-spawning an > > application process, or initiating a control-plane fail-over. > > You talk about time senstive and then you talk about bash scripts. > I don't think your definition of time-sensitive and my definition match. When the process image is measured in hundreds of gigabytes, the corefile can take a while even by /bin/bash standards. You want fun, watch an HPC process manage to OOM a machine with 3T of RAM in a way that produces a full image coredump. 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