mm: add dma_addr_t to struct page

The page_pool API is using page->private to store DMA addresses.
As pointed out by David Miller we can't use that on 32-bit architectures
with 64-bit DMA

This patch adds a new dma_addr_t struct to allow storing DMA addresses

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/mm_types.h

@@ -95,6 +95,13 @@ struct page {
 			 */
 			unsigned long private;
 		};
+		struct {	/* page_pool used by netstack */
+			/**
+			 * @dma_addr: might require a 64-bit value even on
+			 * 32-bit architectures.
+			 */
+			dma_addr_t dma_addr;
+		};
 		struct {	/* slab, slob and slub */
 			union {
 				struct list_head slab_list;	/* uses lru */