[PATCH] percpu: km: ensure it is used with NOMMU (either UP or SMP)

[Vladimir Murzin <vladimir.murzin@arm.com>]

Currently, NOMMU pull km allocator via !SMP dependency because most of
them are UP, yet for SMP+NOMMU vm allocator gets pulled which:

* may lead to broken build [1]
* ...or not working runtime due to [2]

It looks like SMP+NOMMU case was overlooked in bbddff054587 ("percpu:
use percpu allocator on UP too") so restore that.

[1]
For ARM SMP+NOMMU (R-class cores)

arm-none-linux-gnueabihf-ld: mm/percpu.o: in function `pcpu_post_unmap_tlb_flush':
mm/percpu-vm.c:188: undefined reference to `flush_tlb_kernel_range'

[2]
static inline
int vmap_pages_range_noflush(unsigned long addr, unsigned long end,
                pgprot_t prot, struct page **pages, unsigned int page_shift)
{
       return -EINVAL;
}

Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
---
 mm/Kconfig | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/Kconfig b/mm/Kconfig
index d16ba92..66331e0 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -425,9 +425,8 @@ config THP_SWAP
 # UP and nommu archs use km based percpu allocator
 #
 config NEED_PER_CPU_KM
-	depends on !SMP
 	bool
-	default y
+	default !SMP || !MMU
 
 config CLEANCACHE
 	bool "Enable cleancache driver to cache clean pages if tmem is present"
-- 
2.7.4