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=-5.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 EA61BC433E0 for ; Sun, 17 May 2020 10:27:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B9D4520657 for ; Sun, 17 May 2020 10:27:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727122AbgEQK1a (ORCPT ); Sun, 17 May 2020 06:27:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50660 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727081AbgEQK1a (ORCPT ); Sun, 17 May 2020 06:27:30 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E5FC9C061A0C; Sun, 17 May 2020 03:27:29 -0700 (PDT) Received: from p5de0bf0b.dip0.t-ipconnect.de ([93.224.191.11] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jaGVI-0001pW-Da; Sun, 17 May 2020 12:26:44 +0200 Received: by nanos.tec.linutronix.de (Postfix, from userid 1000) id CBD0A100F17; Sun, 17 May 2020 12:26:43 +0200 (CEST) From: Thomas Gleixner To: paulmck@kernel.org, "Joel Fernandes \(Google\)" Cc: linux-kernel@vger.kernel.org, Andy Lutomirski , Frederic Weisbecker , frextrite@gmail.com, Ingo Molnar , Josh Triplett , kernel-team@android.com, Lai Jiangshan , madhuparnabhowmik04@gmail.com, Mathieu Desnoyers , peterz@infradead.org, Petr Mladek , rcu@vger.kernel.org, rostedt@goodmis.org, vpillai@digitalocean.com Subject: Re: [PATCH v3 0/5] RCU dyntick nesting counter cleanups for rcu -dev In-Reply-To: <20200516171223.GC2639@paulmck-ThinkPad-P72> References: <20200504120505.89351-1-joel@joelfernandes.org> <20200504171532.GR2869@paulmck-ThinkPad-P72> <20200504174413.GA8883@paulmck-ThinkPad-P72> <20200516171223.GC2639@paulmck-ThinkPad-P72> Date: Sun, 17 May 2020 12:26:43 +0200 Message-ID: <87wo5adfh8.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: rcu-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org Paul, "Paul E. McKenney" writes: > And I have allegedly resolved the conflicts with Thomas's and Peter's > series, or at least the noinstr-rcu-nmi-2020-05-15 branch of that series. > At least one conflict was completely invisible to "git rebase" (but > fortunately blindingly obvious to the compiler). This naturally makes > me suspect that additional adjustments might be needed. Especially > given that misplaced instrumentation_begin() and instrumentation_end() > calls are invisible not only to the compiler, but also to rcutorture in > my setup. (For example, tracing before instrumentation_begin() or after > instrumentation_end() is a bug.) there is tooling to verify that. If you merge git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git entry-v7-full into your dev branch (trivial conflict) and after building it, run: objtool check -fal $BUILDIR/vmlinux.o Note: This only covers built-in code. So if you have code you want to check make sure it's not built as module. Just did that and it complains about: ../build/vmlinux.o: warning: objtool: rcu_eqs_enter.constprop.0()+0xa9: call to rcu_preempt_deferred_qs() leaves .noinstr.text section But that's even the case on my branch without your changes. The call to rcu_preempt_deferred_qs() is definitely before instrumentation_end() so this needs to be investigated on the objtool side. Peter? Thanks, tglx