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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=unavailable 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 0C9CDC4321A for ; Fri, 28 Jun 2019 01:13:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DE010208E3 for ; Fri, 28 Jun 2019 01:13:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726658AbfF1BNI (ORCPT ); Thu, 27 Jun 2019 21:13:08 -0400 Received: from mail.kernel.org ([198.145.29.99]:48332 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726647AbfF1BNI (ORCPT ); Thu, 27 Jun 2019 21:13:08 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 20CA6206A2; Fri, 28 Jun 2019 01:13:06 +0000 (UTC) Date: Thu, 27 Jun 2019 21:13:04 -0400 From: Steven Rostedt To: Josh Poimboeuf Cc: Thomas Gleixner , Petr Mladek , Miroslav Benes , Jessica Yu , Jiri Kosina , Joe Lawrence , linux-kernel@vger.kernel.org, live-patching@vger.kernel.org, Johannes Erdfelt , Ingo Molnar , mhiramat@kernel.org, torvalds@linux-foundation.org Subject: Re: [PATCH] ftrace: Remove possible deadlock between register_kprobe() and ftrace_run_update_code() Message-ID: <20190627211304.7e21fd77@gandalf.local.home> In-Reply-To: <20190627231952.nqkbtcculvo2ddif@treble> References: <20190627081334.12793-1-pmladek@suse.com> <20190627224729.tshtq4bhzhneq24w@treble> <20190627190457.703a486e@gandalf.local.home> <20190627231952.nqkbtcculvo2ddif@treble> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: live-patching-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: live-patching@vger.kernel.org On Thu, 27 Jun 2019 18:19:52 -0500 Josh Poimboeuf wrote: > Maybe a comment or two would help though. > I'm adding the following change. Care to add a "reviewed-by" for this one? -- Steve diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c index 33786044d5ac..d7e93b2783fd 100644 --- a/arch/x86/kernel/ftrace.c +++ b/arch/x86/kernel/ftrace.c @@ -36,6 +36,11 @@ int ftrace_arch_code_modify_prepare(void) { + /* + * Need to grab text_mutex to prevent a race from module loading + * and live kernel patching from changing the text permissions while + * ftrace has it set to "read/write". + */ mutex_lock(&text_mutex); set_kernel_text_rw(); set_all_modules_text_rw();