3 files changed, 21 insertions, 11 deletions

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 39d49ecea8e8..20117a4b8ab6 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -18,6 +18,7 @@
 #include <asm/pgtable.h>
 
 #include <linux/hugetlb.h>
+#include "internal.h"
 
 const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
 static unsigned long nr_huge_pages, free_huge_pages;
@@ -106,7 +107,7 @@ struct page *alloc_huge_page(struct vm_area_struct *vma, unsigned long addr)
                 return NULL;
         }
         spin_unlock(&hugetlb_lock);
-        set_page_count(page, 1);
+        set_page_refcounted(page);
         for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); ++i)
                 clear_user_highpage(&page[i], addr);
         return page;
@@ -152,7 +153,7 @@ static void update_and_free_page(struct page *page)
                                 1 << PG_private | 1<< PG_writeback);
         }
         page[1].lru.next = NULL;
-        set_page_count(page, 1);
+        set_page_refcounted(page);
         __free_pages(page, HUGETLB_PAGE_ORDER);
 }
 
diff --git a/mm/internal.h b/mm/internal.h
index 7bb339779818..d20e3cc4aef0 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -13,8 +13,19 @@
 
 #include <linux/mm.h>
 
-static inline void set_page_refs(struct page *page, int order)
+static inline void set_page_count(struct page *page, int v)
 {
+        atomic_set(&page->_count, v);
+}
+
+/*
+ * Turn a non-refcounted page (->_count == 0) into refcounted with
+ * a count of one.
+ */
+static inline void set_page_refcounted(struct page *page)
+{
+        BUG_ON(PageCompound(page) && page_private(page) != (unsigned long)page);
+        BUG_ON(atomic_read(&page->_count));
         set_page_count(page, 1);
 }
 
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e197818a7cf6..7f65b5a63bb3 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -442,7 +442,7 @@ void fastcall __init __free_pages_bootmem(struct page *page, unsigned int order)
         if (order == 0) {
                 __ClearPageReserved(page);
                 set_page_count(page, 0);
-                set_page_refs(page, 0);
+                set_page_refcounted(page);
                 __free_page(page);
         } else {
                 int loop;
@@ -457,7 +457,7 @@ void fastcall __init __free_pages_bootmem(struct page *page, unsigned int order)
                         set_page_count(p, 0);
                 }
 
-                set_page_refs(page, order);
+                set_page_refcounted(page);
                 __free_pages(page, order);
         }
 }
@@ -525,7 +525,7 @@ static int prep_new_page(struct page *page, int order)
                         1 << PG_referenced | 1 << PG_arch_1 |
                         1 << PG_checked | 1 << PG_mappedtodisk);
         set_page_private(page, 0);
-        set_page_refs(page, order);
+        set_page_refcounted(page);
         kernel_map_pages(page, 1 << order, 1);
         return 0;
 }
@@ -755,10 +755,8 @@ void split_page(struct page *page, unsigned int order)
 
         BUG_ON(PageCompound(page));
         BUG_ON(!page_count(page));
-        for (i = 1; i < (1 << order); i++) {
-                BUG_ON(page_count(page + i));
-                set_page_count(page + i, 1);
-        }
+        for (i = 1; i < (1 << order); i++)
+                set_page_refcounted(page + i);
 }
 
 /*
@@ -1771,7 +1769,7 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
                         continue;
                 page = pfn_to_page(pfn);
                 set_page_links(page, zone, nid, pfn);
-                set_page_count(page, 1);
+                init_page_count(page);
                 reset_page_mapcount(page);
                 SetPageReserved(page);
                 INIT_LIST_HEAD(&page->lru);