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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 56D6AC28CF6 for ; Wed, 1 Aug 2018 14:19:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0A62B208A3 for ; Wed, 1 Aug 2018 14:19:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0A62B208A3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.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 S2389542AbeHAQFQ (ORCPT ); Wed, 1 Aug 2018 12:05:16 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:40728 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2389448AbeHAQFQ (ORCPT ); Wed, 1 Aug 2018 12:05:16 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 871BA40241C0; Wed, 1 Aug 2018 14:19:17 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.34.27.30]) by smtp.corp.redhat.com (Postfix) with SMTP id 5175C2026D68; Wed, 1 Aug 2018 14:19:15 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Wed, 1 Aug 2018 16:19:17 +0200 (CEST) Date: Wed, 1 Aug 2018 16:19:15 +0200 From: Oleg Nesterov To: =?iso-8859-1?Q?J=FCrg?= Billeter Cc: Andrew Morton , Thomas Gleixner , Eric Biederman , linux-api@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] prctl: add PR_[GS]ET_KILLABLE Message-ID: <20180801141914.GA21248@redhat.com> References: <20180730075241.24002-1-j@bitron.ch> <20180731070337.61004-1-j@bitron.ch> <20180731143949.GA1890@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Wed, 01 Aug 2018 14:19:17 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Wed, 01 Aug 2018 14:19:17 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'oleg@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/31, Jürg Billeter wrote: > > > Could you explain your use-case? Why a shell wants to use > > CLONE_NEWPID? > > To guarantee that there won't be any runaway processes, i.e., ensure > that no descendants (background helper daemons or misbehaving > processes) survive when the child process is terminated. We already have PR_SET_CHILD_SUBREAPER. Perhaps we can finally add PR_KILL_MY_DESCENDANTS_ON_EXIT? This was already discussed some time ago, but I can't find the previous discussion... Simple to implement. > And to prevent > children from killing their ancestors. OK, this is the only reason for CLONE_NEWPID which I can understand so far. Not that I understand why this is that useful ;) > > > * As SIGSTOP is ignored when raised from the SIGNAL_UNKILLABLE process > > > itself, it's not possible to implement the stop action in a custom > > > SIGTSTP handler. > > > > Yes. So may be we actually want to change __isig() paths to use > > SEND_SIG_FORCED (this is not that simple), or perhaps we can change > > __send_signal() to not drop SIGSTOP sent to itself, or may be we can even > > introduce SIG_DFL_EVEN_IF_INIT, I dunno. > > In my opinion, my patch is much simpler and also more general as it Yes, yes, let me repeat that I am not arguing with your patch, I am just trying to understand what > > I can't understand this. An application should be changed anyway to do > > PR_SET_KILLABLE? > > PR_SET_KILLABLE can be called (e.g., by the shell) between clone() and > execve(). OK, this is true. Oleg.