1 files changed, 7 insertions, 5 deletions

diff --git a/mm/cma.c b/mm/cma.c
index 75016fd1de90..68ecb7a42983 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -64,15 +64,17 @@ static unsigned long cma_bitmap_aligned_mask(struct cma *cma, int align_order)
         return (1UL << (align_order - cma->order_per_bit)) - 1;
 }
 
+/*
+ * Find a PFN aligned to the specified order and return an offset represented in
+ * order_per_bits.
+ */
 static unsigned long cma_bitmap_aligned_offset(struct cma *cma, int align_order)
 {
-        unsigned int alignment;
-
         if (align_order <= cma->order_per_bit)
                 return 0;
-        alignment = 1UL << (align_order - cma->order_per_bit);
-        return ALIGN(cma->base_pfn, alignment) -
-                (cma->base_pfn >> cma->order_per_bit);
+
+        return (ALIGN(cma->base_pfn, (1UL << align_order))
+                - cma->base_pfn) >> cma->order_per_bit;
 }
 
 static unsigned long cma_bitmap_maxno(struct cma *cma)