From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A845FBA45 for ; Tue, 7 Mar 2023 17:55:50 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 01D4CC433EF; Tue, 7 Mar 2023 17:55:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678211750; bh=PswiiseGRTu56WIQX20FDgACfRxp6YRvHOPk/80Avh4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=am6nwK3nf2crdF1120GwLuT88f5rEJXhC/fblmyccx3iweZYv6iV/fPlrNy9clZ+U oMt70q48v7wwGzCLz7h6Su1FvUQUkFyUkRzeLKcCbarVYbp3YC9JEKmLMK2VfalMZo FL4o6yBmdOwiACiaZJJeRn0eTNLOuekk54dnyOD8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Guilherme G. Piccoli" , Baoquan He , Dave Young , Feng Tang , HATAYAMA Daisuke , Hidehiro Kawai , Kees Cook , Michael Kelley , Petr Mladek , Vivek Goyal , Andrew Morton Subject: [PATCH 6.2 0933/1001] panic: fix the panic_print NMI backtrace setting Date: Tue, 7 Mar 2023 18:01:45 +0100 Message-Id: <20230307170102.594549952@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230307170022.094103862@linuxfoundation.org> References: <20230307170022.094103862@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Guilherme G. Piccoli commit b905039e428d639adeebb719b76f98865ea38d4d upstream. 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 Signed-off-by: Greg Kroah-Hartman --- kernel/panic.c | 44 ++++++++++++++++++++++++++------------------ 1 file changed, 26 insertions(+), 18 deletions(-) --- a/kernel/panic.c +++ b/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