mm: disable split page table lock for !MMU

There's no reason to enable split page table lock if don't have page
tables.

It also triggers build error at least on ARM since we don't define
pmd_page() for !MMU.

  In file included from arch/arm/kernel/asm-offsets.c:14:0:
  include/linux/mm.h: In function 'pte_lockptr':
  include/linux/mm.h:1392:2: error: implicit declaration of function 'pmd_page' [-Werror=implicit-function-declaration]
  include/linux/mm.h:1392:2: warning: passing argument 1 of 'ptlock_ptr' makes pointer from integer without a cast [enabled by default]
  include/linux/mm.h:1384:27: note: expected 'struct page *' but argument is of type 'int'

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/mm/Kconfig b/mm/Kconfig
index 2888024e0b0a..37fbe1ef5239 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -216,6 +216,7 @@ config PAGEFLAGS_EXTENDED
 #
 config SPLIT_PTLOCK_CPUS
         int
+        default "999999" if !MMU
         default "999999" if ARM && !CPU_CACHE_VIPT
         default "999999" if PARISC && !PA20
         default "4"