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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 ADBCAC3A589 for ; Tue, 20 Aug 2019 20:40:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7EC1022DD6 for ; Tue, 20 Aug 2019 20:40:08 +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="d9XwoM+6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730821AbfHTUkH (ORCPT ); Tue, 20 Aug 2019 16:40:07 -0400 Received: from merlin.infradead.org ([205.233.59.134]:40494 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729887AbfHTUkG (ORCPT ); Tue, 20 Aug 2019 16:40:06 -0400 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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=mLmr7c8zexEAJWjucH2NPO9ANNs5Tm8KXy2A8sFO3Ls=; b=d9XwoM+6cRiup428FiZC1N+b1 LrNwyDnFfiJgaEF5eLN2hlNS39/mGnvTmbv1jTxQ3cbLsno3VGIgA5np+35tucvrokJQwMzRvczLW T0z+kXrGBjcJ+IW0EUime0ZLwKpYSJP7PV+72GKHKG1bOyGB4pbqSHPdv6bjzK94rrIClKaS2mG8/ rAVaZrau8VJ03VMASQ32J/Biw7aULJPZA47+ptmZougtsUe22QxjmrT+MOXst6BijR9lrLMuWKqnP q5vLs2qAdHkPE3pBBHN2v9CqqYRUqepbZ/jw7JOOO61db5Q1BwZTTNHi3n7sVYmnb5Lx14CGXlwE2 XZAQBJeZw==; 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 (Red Hat Linux)) id 1i0Aut-0005HU-Bm; Tue, 20 Aug 2019 20:39:43 +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 1523B3075FF; Tue, 20 Aug 2019 22:39:07 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 5031720A21FC6; Tue, 20 Aug 2019 22:39:39 +0200 (CEST) Date: Tue, 20 Aug 2019 22:39:39 +0200 From: Peter Zijlstra To: "Paul E. McKenney" Cc: Linus Torvalds , Valentin Schneider , Joel Fernandes , Thomas Gleixner , Alan Stern , Mathieu Desnoyers , rostedt , linux-kernel , Boqun Feng , Will Deacon , David Howells Subject: Re: [PATCH 1/1] Fix: trace sched switch start/stop racy updates Message-ID: <20190820203939.GV2349@hirez.programming.kicks-ass.net> References: <241506096.21688.1565977319832.JavaMail.zimbra@efficios.com> <20190816205740.GF10481@google.com> <3c0cb8a2-eba2-7bea-8523-b948253a6804@arm.com> <20190817045217.GZ28441@linux.ibm.com> <20190820140116.GT2332@hirez.programming.kicks-ass.net> <20190820203135.GX28441@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190820203135.GX28441@linux.ibm.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 20, 2019 at 01:31:35PM -0700, Paul E. McKenney wrote: > On Tue, Aug 20, 2019 at 04:01:16PM +0200, Peter Zijlstra wrote: > > We really should get the compiler folks to give us a > > -fno-pointer-provenance. Waiting on the standards committee to get their > > act together seems unlikely, esp. given that some people actually seem > > to _want_ this nonsense :/ > > The reason that they want it is to enable some significant optimizations > in numerical code on the one hand and in heavily templated C++ code on > the other. Neither of which has much bearing on kernel code. > > Interested in coming to the next C standards committee meeting in October > to help me push for this? ;-) How about we try and get some compiler folks together at plumbers and bribe them with beer? Once we have our compiler knob, we happy :-)