From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from eu-smtp-delivery-151.mimecast.com ([185.58.86.151]:32966 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2895243AbgJVJGo (ORCPT ); Thu, 22 Oct 2020 05:06:44 -0400 From: David Laight Subject: RE: Buggy commit tracked to: "Re: [PATCH 2/9] iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c" Date: Thu, 22 Oct 2020 09:06:38 +0000 Message-ID: <96aa868fdee24fd5af8ca06a9bbc0933@AcuMS.aculab.com> References: <20200925045146.1283714-1-hch@lst.de> <20200925045146.1283714-3-hch@lst.de> <20201021161301.GA1196312@kroah.com> <20201021233914.GR3576660@ZenIV.linux.org.uk> <20201022082654.GA1477657@kroah.com> <80a2e5fa-718a-8433-1ab0-dd5b3e3b5416@redhat.com> <5d2ecb24db1e415b8ff88261435386ec@AcuMS.aculab.com> <20201022090155.GA1483166@kroah.com> In-Reply-To: <20201022090155.GA1483166@kroah.com> MIME-Version: 1.0 Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT List-ID: To: 'Greg KH' , David Hildenbrand Cc: Al Viro , Nick Desaulniers , Christoph Hellwig , "kernel-team@android.com" , Andrew Morton , Jens Axboe , Arnd Bergmann , David Howells , "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" From: Greg KH > Sent: 22 October 2020 10:02 ... > I'm running some more tests, trying to narrow things down as just adding > a "noinline" to the function that got moved here doesn't work on Linus's > tree at the moment because the function was split into multiple > functions. I was going to look at that once rc2 is in - and the kernel is likely to work. I suspect the split version doesn't get inlined the same way? Which leaves the horrid argument conversion the inline got rid of back there again. Which all rather begs the question of why the compiler doesn't generate the expected code. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)