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_1 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 C777FC4321A for ; Fri, 28 Jun 2019 01:17:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 96771208CB for ; Fri, 28 Jun 2019 01:17:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726653AbfF1BRh (ORCPT ); Thu, 27 Jun 2019 21:17:37 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37110 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726633AbfF1BRh (ORCPT ); Thu, 27 Jun 2019 21:17:37 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B6BF2307CDD5; Fri, 28 Jun 2019 01:17:36 +0000 (UTC) Received: from treble (ovpn-126-66.rdu2.redhat.com [10.10.126.66]) by smtp.corp.redhat.com (Postfix) with ESMTPS id AE6215D9D2; Fri, 28 Jun 2019 01:17:28 +0000 (UTC) Date: Thu, 27 Jun 2019 20:17:25 -0500 From: Josh Poimboeuf To: Steven Rostedt 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: <20190628011725.rctv3chdlqwkfwcx@treble> References: <20190627081334.12793-1-pmladek@suse.com> <20190627224729.tshtq4bhzhneq24w@treble> <20190627190457.703a486e@gandalf.local.home> <20190627231952.nqkbtcculvo2ddif@treble> <20190627211304.7e21fd77@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190627211304.7e21fd77@gandalf.local.home> User-Agent: NeoMutt/20180716 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.49]); Fri, 28 Jun 2019 01:17:36 +0000 (UTC) Sender: live-patching-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: live-patching@vger.kernel.org On Thu, Jun 27, 2019 at 09:13:04PM -0400, Steven Rostedt wrote: > 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(); For the patch+comment: Reviewed-by: Josh Poimboeuf -- Josh