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=-2.4 required=3.0 tests=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 EE7A2C43603 for ; Mon, 16 Dec 2019 17:28:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B9F5C206E0 for ; Mon, 16 Dec 2019 17:28:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="B0kyRLtb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726559AbfLPR2y (ORCPT ); Mon, 16 Dec 2019 12:28:54 -0500 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:48141 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725805AbfLPR2y (ORCPT ); Mon, 16 Dec 2019 12:28:54 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1576517333; 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=UR5CZgArpnQ0KTZw5vKjrnTKa8Ehpqd+MbgqstFeosw=; b=B0kyRLtbL1ompsE/uSLqFpCRh71PrfvfqyW5pqDLp0iMN9/vBM8JZD+MEW5a2GbAP6jjFP 7IcLY3Yz96V4zUtgq4T3TC0gcWipWaVtVY7V/FvfyRAagSF/BpE8Kuye4VRskDBmh7LDL0 zCZT9kmOGt81R2tlFe1xAKQeuLzslGk= 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-237-Q_rZRP1NPriT__-Tkj8LOw-1; Mon, 16 Dec 2019 12:28:50 -0500 X-MC-Unique: Q_rZRP1NPriT__-Tkj8LOw-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 7537418B6457; Mon, 16 Dec 2019 17:28:48 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.43.17.44]) by smtp.corp.redhat.com (Postfix) with SMTP id E8B125C28D; Mon, 16 Dec 2019 17:28:45 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Mon, 16 Dec 2019 18:28:44 +0100 (CET) Date: Mon, 16 Dec 2019 18:28:41 +0100 From: Oleg Nesterov To: qiwuchen55@gmail.com Cc: christian.brauner@ubuntu.com, peterz@infradead.org, mingo@kernel.org, kernel-team@android.com, linux-kernel@vger.kernel.org, chenqiwu@xiaomi.com Subject: Re: [PATCH v2] kernel/exit: do panic earlier to get coredump if global init task exit Message-ID: <20191216172841.GA10466@redhat.com> References: <1576466324-6067-1-git-send-email-qiwuchen55@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1576466324-6067-1-git-send-email-qiwuchen55@gmail.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/16, qiwuchen55@gmail.com wrote: > > + * If all threads of global init have exited, do panic imeddiately > + * to get the coredump to find any clue for init task in userspace. > + */ > + group_dead = atomic_dec_and_test(&tsk->signal->live); > + if (unlikely(is_global_init(tsk) && group_dead)) > + panic("Attempted to kill init! exitcode=0x%08lx\n", code); ^^^^ No, we should not throw out the useful info, please use signal->group_exit_code ?: code as the current code does. And I am worried atomic_dec_and_test() is called too early... Say, acct_process() can report the exit while some sub-thread sleeps in PTRACE_EVENT_EXIT? I'd prefer to not move it up too much, at least before exit_signals(). Oleg.