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=-6.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 AAF64C4363A for ; Wed, 21 Oct 2020 23:39:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 60B9624170 for ; Wed, 21 Oct 2020 23:39:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2507139AbgJUXjc (ORCPT ); Wed, 21 Oct 2020 19:39:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37292 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2439511AbgJUXjc (ORCPT ); Wed, 21 Oct 2020 19:39:32 -0400 Received: from ZenIV.linux.org.uk (zeniv.linux.org.uk [IPv6:2002:c35c:fd02::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 86217C0613CE; Wed, 21 Oct 2020 16:39:31 -0700 (PDT) Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kVNhK-005pSF-DC; Wed, 21 Oct 2020 23:39:14 +0000 Date: Thu, 22 Oct 2020 00:39:14 +0100 From: Al Viro To: Greg KH Cc: Christoph Hellwig , kernel-team@android.com, Andrew Morton , Jens Axboe , Arnd Bergmann , David Howells , David Laight , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, linux-block@vger.kernel.org, linux-scsi@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, io-uring@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, keyrings@vger.kernel.org, linux-security-module@vger.kernel.org Subject: Re: Buggy commit tracked to: "Re: [PATCH 2/9] iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c" Message-ID: <20201021233914.GR3576660@ZenIV.linux.org.uk> References: <20200925045146.1283714-1-hch@lst.de> <20200925045146.1283714-3-hch@lst.de> <20201021161301.GA1196312@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201021161301.GA1196312@kroah.com> Sender: Al Viro Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org On Wed, Oct 21, 2020 at 06:13:01PM +0200, Greg KH wrote: > On Fri, Sep 25, 2020 at 06:51:39AM +0200, Christoph Hellwig wrote: > > From: David Laight > > > > This lets the compiler inline it into import_iovec() generating > > much better code. > > > > Signed-off-by: David Laight > > Signed-off-by: Christoph Hellwig > > --- > > fs/read_write.c | 179 ------------------------------------------------ > > lib/iov_iter.c | 176 +++++++++++++++++++++++++++++++++++++++++++++++ > > 2 files changed, 176 insertions(+), 179 deletions(-) > > Strangely, this commit causes a regression in Linus's tree right now. > > I can't really figure out what the regression is, only that this commit > triggers a "large Android system binary" from working properly. There's > no kernel log messages anywhere, and I don't have any way to strace the > thing in the testing framework, so any hints that people can provide > would be most appreciated. It's a pure move - modulo changed line breaks in the argument lists the functions involved are identical before and after that (just checked that directly, by checking out the trees before and after, extracting two functions in question from fs/read_write.c and lib/iov_iter.c (before and after, resp.) and checking the diff between those. How certain is your bisection?