From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx171.postini.com [74.125.245.171]) by kanga.kvack.org (Postfix) with SMTP id DCBCA6B0031 for ; Mon, 5 Aug 2013 05:04:58 -0400 (EDT) Date: Mon, 5 Aug 2013 11:04:55 +0200 From: Michal Hocko Subject: Re: [PATCH] MM: Make Contiguous Memory Allocator depends on MMU Message-ID: <20130805090455.GG10146@dhcp22.suse.cz> References: <1375593061-11350-1-git-send-email-manjunath.goudar@linaro.org> <51fe08c6.87ef440a.10fc.1786SMTPIN_ADDED_BROKEN@mx.google.com> <20130805073239.GC10146@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Manjunath Goudar Cc: Wanpeng Li , linux-arm-kernel@lists.infradead.org, patches@linaro.org, arnd@linaro.org, dsaxena@linaro.org, linaro-kernel@lists.linaro.org, IWAMOTO Toshihiro , Hirokazu Takahashi , Dave Hansen , linux-mm@kvack.org, Johannes Weiner , Balbir Singh , KAMEZAWA Hiroyuki , hyojun.im@lge.com, Nataraja KM/LGSIA CSP-4 On Mon 05-08-13 14:07:41, Manjunath Goudar wrote: > On 5 August 2013 13:02, Michal Hocko wrote: > > > On Mon 05-08-13 10:10:08, Manjunath Goudar wrote: > > > On 4 August 2013 13:24, Wanpeng Li wrote: > > > > > > > On Sun, Aug 04, 2013 at 10:41:01AM +0530, Manjunath Goudar wrote: > > > > >s patch adds a Kconfig dependency on an MMU being available before > > > > >CMA can be enabled. Without this patch, CMA can be enabled on an > > > > >MMU-less system which can lead to issues. This was discovered during > > > > >randconfig testing, in which CMA was enabled w/o MMU being enabled, > > > > >leading to the following error: > > > > > > > > > > CC mm/migrate.o > > > > >mm/migrate.c: In function a??remove_migration_ptea??: > > > > >mm/migrate.c:134:3: error: implicit declaration of function > > > > a??pmd_trans_hugea?? > > > > >[-Werror=implicit-function-declaration] > > > > > if (pmd_trans_huge(*pmd)) > > > > > ^ > > > > >mm/migrate.c:137:3: error: implicit declaration of function > > > > a??pte_offset_mapa?? > > > > >[-Werror=implicit-function-declaration] > > > > > ptep = pte_offset_map(pmd, addr); > > > > > > > > > > > > > Similar one. > > > > > > > > http://marc.info/?l=linux-mm&m=137532486405085&w=2 > > > > > > > > > In this patch MIGRATION config is not required MMU, because already CMA > > > config depends > > > on MMU and HAVE_MEMBLOCK if both are true then only selecting MIGRATION > > and > > > MEMORY_ISOLATION. > > > > No, I think it should be config MIGRATION that should depend on MMU > > explicitly because that is where the problem exists. It shouldn't rely > > on other configs to not select it automatically. > > > > Yes you are correct. > > > The question is. Does CMA need to depend on MMU as well? Why? > > But please comment on the original thread instead. > > > > I went through the mm/Kconfig, I think MMU dependence is not required > for CMA. OK, it turned out that it is needed in the end. Kcofing forces selects so CMA config would force MIGRATION even if that one depends on MMU. -- Michal Hocko SUSE Labs -- 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