On 4 August 2013 13:24, Wanpeng Li <liwanp@linux.vnet.ibm.com> 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.

>
>
> >Signed-off-by: Manjunath Goudar <manjunath.goudar@linaro.org>
> >Acked-by: Arnd Bergmann <arnd@linaro.org>
> >Cc: Deepak Saxena <dsaxena@linaro.org>
> >Cc: IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
> >Cc: Hirokazu Takahashi <taka@valinux.co.jp>
> >Cc: Dave Hansen <haveblue@us.ibm.com>
> >Cc: linux-mm@kvack.org
> >Cc: Johannes Weiner <hannes@cmpxchg.org>
> >Cc: Michal Hocko <mhocko@suse.cz>
> >Cc: Balbir Singh <bsingharora@gmail.com>
> >Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> >---
> > mm/Kconfig |    2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> >diff --git a/mm/Kconfig b/mm/Kconfig
> >index 256bfd0..ad6b98e 100644
> >--- a/mm/Kconfig
> >+++ b/mm/Kconfig
> >@@ -522,7 +522,7 @@ config MEM_SOFT_DIRTY
> >
> > config CMA
> >       bool "Contiguous Memory Allocator"
> >-      depends on HAVE_MEMBLOCK
> >+      depends on MMU && HAVE_MEMBLOCK
> >       select MIGRATION
> >       select MEMORY_ISOLATION
> >       help
> >--
> >1.7.9.5
> >
> >--
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> >see: http://www.linux-mm.org/ .
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>
> Thanks
Manjunath Goudar