[PATCH] powerpc/mm: Only define MAX_PHYSMEM_BITS in SPARSEMEM configurations

[Ben Hutchings]

MAX_PHYSMEM_BITS only needs to be defined if CONFIG_SPARSEMEM is
enabled, and that was the case before commit 4ffe713b7587
("powerpc/mm: Increase the max addressable memory to 2PB").

On 32-bit systems, where CONFIG_SPARSEMEM is not enabled, we now
define it as 46.  That is larger than the real number of physical
address bits, and breaks calculations in zsmalloc:

    mm/zsmalloc.c:130:49: warning: right shift count is negative [-Wshift-count-negative]
      MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
                                                     ^~
    ...
    mm/zsmalloc.c:253:21: error: variably modified 'size_class' at file scope
      struct size_class *size_class[ZS_SIZE_CLASSES];
                         ^~~~~~~~~~

Fixes: 4ffe713b7587 ("powerpc/mm: Increase the max addressable memory to 2PB")
Cc: stable at vger.kernel.org
Signed-off-by: Ben Hutchings <ben at decadent.org.uk>
---
 arch/powerpc/include/asm/mmu.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
index 25607604a7a5..2bc8c3f04f8a 100644
--- a/arch/powerpc/include/asm/mmu.h
+++ b/arch/powerpc/include/asm/mmu.h
@@ -341,7 +341,7 @@ static inline u16 get_mm_addr_key(struct mm_struct *mm, unsigned long address)
 #if defined(CONFIG_SPARSEMEM_VMEMMAP) && defined(CONFIG_SPARSEMEM_EXTREME) &&	\
 	defined (CONFIG_PPC_64K_PAGES)
 #define MAX_PHYSMEM_BITS        51
-#else
+#elif defined(CONFIG_SPARSEMEM)
 #define MAX_PHYSMEM_BITS        46
 #endif
 
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