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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 780CDC433E0 for ; Fri, 29 May 2020 20:14:45 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3AB8C20C09 for ; Fri, 29 May 2020 20:14:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3AB8C20C09 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zeniv.linux.org.uk Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id C51958001A; Fri, 29 May 2020 16:14:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BFFB680010; Fri, 29 May 2020 16:14:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AEEA98001A; Fri, 29 May 2020 16:14:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0085.hostedemail.com [216.40.44.85]) by kanga.kvack.org (Postfix) with ESMTP id 936A680010 for ; Fri, 29 May 2020 16:14:44 -0400 (EDT) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 5040C181AEF10 for ; Fri, 29 May 2020 20:14:44 +0000 (UTC) X-FDA: 76870859688.02.self88_2951d14b4c348 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin02.hostedemail.com (Postfix) with ESMTP id 3776D5830 for ; Fri, 29 May 2020 20:14:44 +0000 (UTC) X-HE-Tag: self88_2951d14b4c348 X-Filterd-Recvd-Size: 3004 Received: from ZenIV.linux.org.uk (zeniv.linux.org.uk [195.92.253.2]) by imf18.hostedemail.com (Postfix) with ESMTP for ; Fri, 29 May 2020 20:14:43 +0000 (UTC) Received: from viro by ZenIV.linux.org.uk with local (Exim 4.93 #3 (Red Hat Linux)) id 1jelOk-000794-SV; Fri, 29 May 2020 20:14:34 +0000 Date: Fri, 29 May 2020 21:14:34 +0100 From: Al Viro To: Linus Torvalds Cc: Josh Poimboeuf , Peter Zijlstra , Christoph Hellwig , Randy Dunlap , Andrew Morton , Mark Brown , linux-fsdevel , Linux Kernel Mailing List , Linux-MM , Linux Next Mailing List , Michal Hocko , mm-commits@vger.kernel.org, Stephen Rothwell , the arch/x86 maintainers , Steven Rostedt Subject: Re: mmotm 2020-05-13-20-30 uploaded (objtool warnings) Message-ID: <20200529201434.GH23230@ZenIV.linux.org.uk> References: <20200528172005.GP2483@worktop.programming.kicks-ass.net> <20200529135750.GA1580@lst.de> <20200529143556.GE706478@hirez.programming.kicks-ass.net> <20200529145325.GB706518@hirez.programming.kicks-ass.net> <20200529153336.GC706518@hirez.programming.kicks-ass.net> <20200529160514.cyaytn33thphb3tz@treble> <20200529161253.GD706460@hirez.programming.kicks-ass.net> <20200529165011.o7vvhn4wcj6zjxux@treble> <20200529200856.GG23230@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200529200856.GG23230@ZenIV.linux.org.uk> X-Rspamd-Queue-Id: 3776D5830 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, May 29, 2020 at 09:08:56PM +0100, Al Viro wrote: > On Fri, May 29, 2020 at 12:31:04PM -0700, Linus Torvalds wrote: > > On Fri, May 29, 2020 at 9:50 AM Josh Poimboeuf wrote: > > > > > > From staring at the asm I think the generated code is correct, it's just > > > that the nested likelys with ftrace profiling cause GCC to converge the > > > error/success paths. But objtool doesn't do register value tracking so > > > it's not smart enough to know that it's safe. > > > > I'm surprised that gcc doesn't end up doing the obvious CSE and then > > branch following and folding it all away in the end, but your patch is > > obviously the right thing to do regardless, so ack on that. > > > > Al - I think this had best go into your uaccess cleanup branch with > > that csum-wrapper update, to avoid any unnecessary conflicts or > > dependencies. > > Sure, just let me verify that other branches don't introduce anything > of that sort... ... they don't. OK, folded, rebuild #for-next, pushed both out...