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 2D5B2C433DB for ; Fri, 19 Mar 2021 16:27:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E691361963 for ; Fri, 19 Mar 2021 16:27:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229991AbhCSQ1N (ORCPT ); Fri, 19 Mar 2021 12:27:13 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:47614 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230041AbhCSQ1A (ORCPT ); Fri, 19 Mar 2021 12:27:00 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1616171219; 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=p64iFkslqxnuTZmrG9ex1+VZNpSbfarQfW4/L2fWYZs=; b=haPe1CEcLMmHwUmDSJjpblPb6gu/+hI0/lz36/4+2HbmBTfS8k74fHgVHhp1cwDxVcYDOP MdnNbjR/0tCYC+kYEMByT+Xwuq6ADZa5smU8rDX28Lwghfbu6a76xx1/VFwhFUEnLwik2G E4RSt2/PSlia6ZB1eF/+mQEt+wW/XSA= 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-242-Tld3CbwTPDKbtt1KjT2dPg-1; Fri, 19 Mar 2021 12:26:56 -0400 X-MC-Unique: Tld3CbwTPDKbtt1KjT2dPg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B5E4F107ACCA; Fri, 19 Mar 2021 16:26:53 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.40.195.172]) by smtp.corp.redhat.com (Postfix) with SMTP id 7A15460BF1; Fri, 19 Mar 2021 16:26:51 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Fri, 19 Mar 2021 17:26:53 +0100 (CET) Date: Fri, 19 Mar 2021 17:26:50 +0100 From: Oleg Nesterov To: "Eric W. Biederman" Cc: qianli zhao , christian@brauner.io, axboe@kernel.dk, 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: <20210319162649.GA19971@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 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/18, Eric W. Biederman wrote: > > Oleg Nesterov writes: > > > On 03/18, qianli zhao wrote: > >> > >> In addition, the patch also protects the init process state to > >> successfully get usable init coredump. > > > > Could you spell please? > > > > Does this connect to SIGNAL_GROUP_EXIT check? Do you mean that you want > > to panic earlier, before other init's sub-threads exit? > > That is my understanding. > > As I understand it this patch has two purposes: > 1. Avoid the BUG_ON in zap_pid_ns_processes when !CONFIG_PID_NS > 2. panic as early as possible so exiting threads don't removing > interesting debugging state. Yes, this was my understanding too, but the changelog didn't look clear to me. And I'd say that it is not that we want to avoid BUG_ON() in zap_pid_ns_processes() when !CONFIG_PID_NS, we want to avoid zap_pid_ns_processes() in the root namespace, regardless of CONFIG_PID_NS. > It is a bit tricky to tell if the movement of the decrement of > signal->live is safe. Agreed, this was my concern. I see nothing wrong at first glance, but I can easily miss something. Oleg.