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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 802ABC7EE37 for ; Fri, 3 Mar 2023 05:55:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229754AbjCCFzp (ORCPT ); Fri, 3 Mar 2023 00:55:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42418 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229633AbjCCFzm (ORCPT ); Fri, 3 Mar 2023 00:55:42 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ABEA639BBD; Thu, 2 Mar 2023 21:55:04 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 45113B81606; Fri, 3 Mar 2023 05:55:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E1F04C433EF; Fri, 3 Mar 2023 05:55:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1677822902; bh=iHfZBwFCse5ztMSVUxmZpYUodSn6St6D/K4W7Hg8NWE=; h=Date:To:From:Subject:From; b=YWsnZ/jO5Fo63mUilxOzu9apCKKKlpX1lOnwY9+dPlQ6gXzU7HEzFfgoxUevwwnx/ Ex2CGX9fhr99DBpDimQqM6FiYbT3VKSZI3E2W7gU77bylGNbvPnacU+qF+gLurxiA8 sZrQQygQ5G06LfoW7OVmF8QYpOnv54CrXPps2Xck= Date: Thu, 02 Mar 2023 21:55:01 -0800 To: mm-commits@vger.kernel.org, vgoyal@redhat.com, stable@vger.kernel.org, pmladek@suse.com, mikelley@microsoft.com, keescook@chromium.org, hidehiro.kawai.ez@hitachi.com, feng.tang@intel.com, dyoung@redhat.com, d.hatayama@jp.fujitsu.com, bhe@redhat.com, gpiccoli@igalia.com, akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-hotfixes-stable] panic-fixes-the-panic_print-nmi-backtrace-setting.patch removed from -mm tree Message-Id: <20230303055501.E1F04C433EF@smtp.kernel.org> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The quilt patch titled Subject: panic: fix the panic_print NMI backtrace setting has been removed from the -mm tree. Its filename was panic-fixes-the-panic_print-nmi-backtrace-setting.patch This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: "Guilherme G. Piccoli" Subject: panic: fix the panic_print NMI backtrace setting Date: Sun, 26 Feb 2023 13:08:38 -0300 Commit 8d470a45d1a6 ("panic: add option to dump all CPUs backtraces in panic_print") introduced a setting for the "panic_print" kernel parameter to allow users to request a NMI backtrace on panic. Problem is that the panic_print handling happens after the secondary CPUs are already disabled, hence this option ended-up being kind of a no-op - kernel skips the NMI trace in idling CPUs, which is the case of offline CPUs. Fix it by checking the NMI backtrace bit in the panic_print prior to the CPU disabling function. Link: https://lkml.kernel.org/r/20230226160838.414257-1-gpiccoli@igalia.com Fixes: 8d470a45d1a6 ("panic: add option to dump all CPUs backtraces in panic_print") Signed-off-by: Guilherme G. Piccoli Cc: Cc: Baoquan He Cc: Dave Young Cc: Feng Tang Cc: HATAYAMA Daisuke Cc: Hidehiro Kawai Cc: Kees Cook Cc: Michael Kelley Cc: Petr Mladek Cc: Vivek Goyal Signed-off-by: Andrew Morton --- --- a/kernel/panic.c~panic-fixes-the-panic_print-nmi-backtrace-setting +++ a/kernel/panic.c @@ -212,9 +212,6 @@ static void panic_print_sys_info(bool co return; } - if (panic_print & PANIC_PRINT_ALL_CPU_BT) - trigger_all_cpu_backtrace(); - if (panic_print & PANIC_PRINT_TASK_INFO) show_state(); @@ -244,6 +241,30 @@ void check_panic_on_warn(const char *ori origin, limit); } +/* + * Helper that triggers the NMI backtrace (if set in panic_print) + * and then performs the secondary CPUs shutdown - we cannot have + * the NMI backtrace after the CPUs are off! + */ +static void panic_other_cpus_shutdown(bool crash_kexec) +{ + if (panic_print & PANIC_PRINT_ALL_CPU_BT) + trigger_all_cpu_backtrace(); + + /* + * Note that smp_send_stop() is the usual SMP shutdown function, + * which unfortunately may not be hardened to work in a panic + * situation. If we want to do crash dump after notifier calls + * and kmsg_dump, we will need architecture dependent extra + * bits in addition to stopping other CPUs, hence we rely on + * crash_smp_send_stop() for that. + */ + if (!crash_kexec) + smp_send_stop(); + else + crash_smp_send_stop(); +} + /** * panic - halt the system * @fmt: The text string to print @@ -334,23 +355,10 @@ void panic(const char *fmt, ...) * * Bypass the panic_cpu check and call __crash_kexec directly. */ - if (!_crash_kexec_post_notifiers) { + if (!_crash_kexec_post_notifiers) __crash_kexec(NULL); - /* - * Note smp_send_stop is the usual smp shutdown function, which - * unfortunately means it may not be hardened to work in a - * panic situation. - */ - smp_send_stop(); - } else { - /* - * If we want to do crash dump after notifier calls and - * kmsg_dump, we will need architecture dependent extra - * works in addition to stopping other CPUs. - */ - crash_smp_send_stop(); - } + panic_other_cpus_shutdown(_crash_kexec_post_notifiers); /* * Run any panic handlers, including those that might need to _ Patches currently in -mm which might be from gpiccoli@igalia.com are