On Mon 05-08-13 14:07:41, Manjunath Goudar wrote: > On 5 August 2013 13:02, Michal Hocko <mhocko@xxxxxxx> wrote: > > > On Mon 05-08-13 10:10:08, Manjunath Goudar wrote: > > > On 4 August 2013 13:24, Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx> 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 ‘remove_migration_pte’: > > > > >mm/migrate.c:134:3: error: implicit declaration of function > > > > ‘pmd_trans_huge’ > > > > >[-Werror=implicit-function-declaration] > > > > > if (pmd_trans_huge(*pmd)) > > > > > ^ > > > > >mm/migrate.c:137:3: error: implicit declaration of function > > > > ‘pte_offset_map’ > > > > >[-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@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>