From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qg0-f44.google.com (mail-qg0-f44.google.com [209.85.192.44]) by kanga.kvack.org (Postfix) with ESMTP id 3AD81280303 for ; Thu, 16 Jul 2015 16:05:42 -0400 (EDT) Received: by qgy5 with SMTP id 5so38007999qgy.3 for ; Thu, 16 Jul 2015 13:05:42 -0700 (PDT) Date: Thu, 16 Jul 2015 22:03:55 +0200 From: Oleg Nesterov Subject: Re: [mmotm:master 140/321] fs/built-in.o:undefined reference to `filemap_page_mkwrite' Message-ID: <20150716200355.GA26594@redhat.com> References: <201507160919.VRGXvreQ%fengguang.wu@intel.com> <20150716190503.GA22146@redhat.com> <20150716191258.GA22760@kvack.org> <20150716193856.GA25255@redhat.com> <20150716194553.GB22760@kvack.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150716194553.GB22760@kvack.org> Sender: owner-linux-mm@kvack.org List-ID: To: Benjamin LaHaise Cc: kbuild test robot , Jeff Moyer , kbuild-all@01.org, Johannes Weiner , Andrew Morton , Linux Memory Management List On 07/16, Benjamin LaHaise wrote: > > On Thu, Jul 16, 2015 at 09:38:56PM +0200, Oleg Nesterov wrote: > > On 07/16, Benjamin LaHaise wrote: > > > > > > On Thu, Jul 16, 2015 at 09:05:03PM +0200, Oleg Nesterov wrote: > > > > Thanks! > > > ... > > > > but the problem looks clear: CONFIG_MMU is not set, so we need > > > > a dummy filemap_page_mkwrite() along with generic_file_mmap() and > > > > generic_file_readonly_mmap(). > > > > > > > > I'll send the fix, but... > > > > > > > > Benjamin, Jeff, shouldn't AIO depend on MMU? Or it can actually work even > > > > if CONFIG_MMU=n? > > > > > > It should work when CONFIG_MMU=n, > > > > Really? I am just curious. > > I am not saying the code currently does, but that the use of the functionality > is valid. The code clearly doesn't at the moment, and given that nobody > has complained, it's seems unlikely that there are any active users. Hmm. Confused... So sys_io_setup() can't succed if CONFIG_MMU=n. Then why do we allow CONFIG_AIO=y in this case? And it is even "default y" and needs EXPERT to disable... But OK, I won't argue. I'll send the fix which fixes the build. Thanks! Oleg. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org