mm: introduce common STRUCT_PAGE_MAX_SHIFT define

[linux-2.6-block.git] / include / linux / mm_types.h

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 5ed8f6292a533c2efbc4390d1a6a165bf4ad2252..2c471a2c43fa7137f1780b976615a6cbef5f6b6e 100644 (file)
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -206,6 +206,11 @@ struct page {
 #endif
 } _struct_page_alignment;
 
+/*
+ * Used for sizing the vmemmap region on some architectures
+ */
+#define STRUCT_PAGE_MAX_SHIFT  (order_base_2(sizeof(struct page)))
+
 #define PAGE_FRAG_CACHE_MAX_SIZE       __ALIGN_MASK(32768, ~PAGE_MASK)
 #define PAGE_FRAG_CACHE_MAX_ORDER      get_order(PAGE_FRAG_CACHE_MAX_SIZE)