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=-12.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 655E5C433C1 for ; Fri, 19 Mar 2021 16:35:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1338B61984 for ; Fri, 19 Mar 2021 16:35:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230064AbhCSQfR (ORCPT ); Fri, 19 Mar 2021 12:35:17 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:42090 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230176AbhCSQew (ORCPT ); Fri, 19 Mar 2021 12:34:52 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1616171692; 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=1WsyL+gZ2Mx6w9qJVMZxIs1oTsKccRsNWKVpGyE4x8w=; b=GaSI+RzssEilR/0x177INhgikL24mywrp4hzNHEO6O5i2GEfE0xFsPp7tuSvjMrbPuPEpv 0GKpYAdvGabb80JyXj36zSRqAl0PVWC64Nlu1CH8SV+HhTNYmBaTaPfpZ9Yr0nJKGHaEiy DVKZ4MOC9ivV9CpKZX2PUceupf9atjE= 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-499-G9mjFXpIOySEKH75kk162Q-1; Fri, 19 Mar 2021 12:34:48 -0400 X-MC-Unique: G9mjFXpIOySEKH75kk162Q-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 97B8C107ACCA; Fri, 19 Mar 2021 16:34:46 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.40.195.172]) by smtp.corp.redhat.com (Postfix) with SMTP id 6CDDA5C1BB; Fri, 19 Mar 2021 16:34:44 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Fri, 19 Mar 2021 17:34:46 +0100 (CET) Date: Fri, 19 Mar 2021 17:34:43 +0100 From: Oleg Nesterov To: qianli zhao Cc: "Eric W. Biederman" , 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: <20210319163442.GC19971@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 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/19, qianli zhao wrote: > > I will think about the risks of movement of the decrement of > signal->live before exit_signal(). > If is difficult to judge movement of the decrement of signal->live is > safe,how about only test 'signal->live==1' not use group_dead? > > Such as: > diff --git a/kernel/exit.c b/kernel/exit.c > index 04029e3..87f3595 100644 > --- a/kernel/exit.c > +++ b/kernel/exit.c > @@ -767,6 +767,17 @@ void __noreturn do_exit(long code) > validate_creds_for_do_exit(tsk); > > /* > + * If global init has exited, > + * panic immediately to get a useable coredump. > + */ > + if (unlikely(is_global_init(tsk) && > + ((atomic_read(&tsk->signal->live) == 1) || /*current is > last init thread*/ Just suppose signal->live == 2 and both init's sub-threads exit at the same time. They both can see signal->live == 2, panic() won't be called. Oleg.