diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index d41957eae6ef..f5dab4e9fb4b 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -2078,7 +2078,7 @@ arm_iommu_create_mapping(struct bus_type *bus, dma_addr_t base, u64 size)
 	mapping->nr_bitmaps = 1;
 	mapping->extensions = extensions;
 	mapping->base = base;
-	mapping->bits = BITS_PER_BYTE * bitmap_size;
+	mapping->bits = bits;
 
 	spin_lock_init(&mapping->lock);
 
diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index 06f9ffccd562..196c73e2cf9c 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -2064,7 +2064,7 @@ arm_iommu_create_mapping(struct bus_type *bus, dma_addr_t base, size_t size)
 		goto err2;
 
 	mapping->base = base;
-	mapping->bits = BITS_PER_BYTE * bitmap_size;
+	mapping->bits = bits;
 	spin_lock_init(&mapping->lock);
 
 	mapping->domain = iommu_domain_alloc(bus);