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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no 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 E4B03C433E6 for ; Wed, 2 Sep 2020 07:08:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B3577208B3 for ; Wed, 2 Sep 2020 07:08:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="xjDLtop+" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726674AbgIBHIl (ORCPT ); Wed, 2 Sep 2020 03:08:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57614 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726140AbgIBHIh (ORCPT ); Wed, 2 Sep 2020 03:08:37 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B966DC061244 for ; Wed, 2 Sep 2020 00:08:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=qSleb5yTfUSbFgVSq70m08ah+KEBG2zQiz3hpXr3Dys=; b=xjDLtop+ezWUw1yQi7d2GwgHEJ iAuovHBN2V2q/2RxbqTIBWym9NtRL4GbVmKroQZBOVUdgWsJhrXVIjmhAF4oP7Nkbz18b2AMazxPc ArKORw8XEUI8ja3UAtIGKiZ3kyaypLeJ+MvJPdiByvJ86H78p+dQKUJuC5WuGrAH+dPvog55m4zRW TXo15E4fGt9jVt6QFCRwijUbORjVCizF7eNnE1YPoFLRXJU9k3sTs1s+eUpBMb+TBAFcrg7S9P0l1 0sxQMMZ8r1hL+RXWfHTGTJpfek9UJJzC0h8tT1V397phtOk1j/LEUabeUCZgoS7kt/HrgzvmCrPbg 2TdgDXqw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kDMsG-00064E-0n; Wed, 02 Sep 2020 07:08:04 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 889F43056DE; Wed, 2 Sep 2020 09:08:00 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 5B27E2B774668; Wed, 2 Sep 2020 09:08:00 +0200 (CEST) Date: Wed, 2 Sep 2020 09:08:00 +0200 From: peterz@infradead.org To: Joel Fernandes Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, will@kernel.org, npiggin@gmail.com, elver@google.com, jgross@suse.com, paulmck@kernel.org, rostedt@goodmis.org, rjw@rjwysocki.net, svens@linux.ibm.com, tglx@linutronix.de, mathieu.desnoyers@efficios.com Subject: Re: [PATCH v2 03/11] sched,idle,rcu: Push rcu_idle deeper into the idle path Message-ID: <20200902070800.GH2674@hirez.programming.kicks-ass.net> References: <20200821084738.508092956@infradead.org> <20200821085348.310943801@infradead.org> <20200827011826.GA1942571@google.com> <20200827012419.GB1942571@google.com> <20200827074748.GY2674@hirez.programming.kicks-ass.net> <20200827223001.GA3821640@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200827223001.GA3821640@google.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 27, 2020 at 06:30:01PM -0400, Joel Fernandes wrote: > On Thu, Aug 27, 2020 at 09:47:48AM +0200, peterz@infradead.org wrote: > > All trace_*_rcuidle() and RCU_NONIDLE() usage is a bug IMO. > > > > Ideally RCU-trace goes away too. > > I was thinking that unless the rcu_idle_enter/exit calls coincide with points > in the kernel where instrumentation is not allowed, there is always a chance > somebody wants to use tracepoints after rcu_idle_enter or before exit. In > this case, trace_*_rcuidle() is unavoidable unless you can move the > rcu_idle_enter/exit calls deeper as you are doing. > > Maybe objtool can help with that? The eventual goal is to mark idle code noinstr too. There's more work before we can do that.