From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: 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: Wed, 21 Oct 2020 20:59:43 +0000 Message-ID: References: <20200925045146.1283714-1-hch@lst.de> <20200925045146.1283714-3-hch@lst.de> <20201021161301.GA1196312@kroah.com> In-Reply-To: <20201021161301.GA1196312@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' , Christoph Hellwig , "kernel-team@android.com" Cc: Alexander Viro , 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: 21 October 2020 17:13 > > 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. My original commit just moved the function source from one file to another. So it is odd that it makes any difference. I don't even know if it gets inlined by Christoph's actual patch. (I have another patch that depended on it that I need to resubmit.) Some of the other changes from Christoph's same patch set might make a difference though. Might be worth forcing it to be not inlined - so it is no change. Or try adding a kernel log to import_iovec() or the associated copy failing. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)