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=-7.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 C98F1C433E0 for ; Fri, 19 Mar 2021 16:33:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9876860238 for ; Fri, 19 Mar 2021 16:33:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230105AbhCSQci (ORCPT ); Fri, 19 Mar 2021 12:32:38 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:28175 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229736AbhCSQcd (ORCPT ); Fri, 19 Mar 2021 12:32:33 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1616171552; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=xuN/BQ3TMCd1X8UMe2lNGsX3GTMn8VHhRpzWPbejhMY=; b=DWVnJwInvFbVSdBDaf+/Kgvqk9Ip1CS1ca3ztbE1Q4yZgeuX/4ZiT0m3lAKcsF+phRLyMu d3/uESQVO6W9u/ioRzrGW3rK+/JcUv3SQNfp24GiMJRGSJDEw6xSa+iclbI2xAS4ry9SZk OFclnI63BMkx9dlNFvvW22uPZg8PzDg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-410-fxBG1fW_NpCnHlafJ7rirQ-1; Fri, 19 Mar 2021 12:32:30 -0400 X-MC-Unique: fxBG1fW_NpCnHlafJ7rirQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 7395B107ACCD; Fri, 19 Mar 2021 16:32:29 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.40.195.172]) by smtp.corp.redhat.com (Postfix) with SMTP id 05AF26091B; Fri, 19 Mar 2021 16:32:26 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Fri, 19 Mar 2021 17:32:28 +0100 (CET) Date: Fri, 19 Mar 2021 17:32:25 +0100 From: Oleg Nesterov To: qianli zhao Cc: christian@brauner.io, axboe@kernel.dk, "Eric W. Biederman" , Thomas Gleixner , Peter Collingbourne , linux-kernel@vger.kernel.org, Qianli Zhao Subject: Re: [PATCH V3] exit: trigger panic when global init has exited Message-ID: <20210319163225.GB19971@redhat.com> References: <1615985460-112867-1-git-send-email-zhaoqianligood@gmail.com> <20210317143805.GA5610@redhat.com> <20210318180450.GA9977@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/19, qianli zhao wrote: > > > But then I don't understand the SIGNAL_GROUP_EXIT check added by your > > patch. Do we really need it if we want to avoid zap_pid_ns_processes() > > when the global init exits? > > I think check SIGNAL_GROUP_EXIT is necessary,or panic() will happen > after all init sub-threads do_exit(),so the following two situations > will happen: > 1.According to the timing in the changelog, > zap_pid_ns_processes()->BUG() maybe happened. How? Perhaps I missed something again, but I don't think this is possible. zap_pid_ns_processes() simply won't be called, find_child_reaper() will see the !PF_EXITING thread which calls panic(). So I think this should be documented somehow, at least in the changelog. Oleg.