[PATCH] MM: Make Contiguous Memory Allocator depends on MMU

[Manjunath Goudar <manjunath.goudar@linaro.org>]

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);

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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