1 files changed, 16 insertions, 0 deletions

diff --git a/mm/util.c b/mm/util.c
index 3704bf1bef94..16a73195a37b 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -5,6 +5,7 @@
 #include <linux/err.h>
 #include <linux/sched.h>
 #include <linux/security.h>
+#include <linux/swap.h>
 #include <asm/uaccess.h>
 
 #include "internal.h"
@@ -382,6 +383,21 @@ unsigned long vm_mmap(struct file *file, unsigned long addr,
 }
 EXPORT_SYMBOL(vm_mmap);
 
+struct address_space *page_mapping(struct page *page)
+{
+        struct address_space *mapping = page->mapping;
+
+        VM_BUG_ON(PageSlab(page));
+#ifdef CONFIG_SWAP
+        if (unlikely(PageSwapCache(page)))
+                mapping = &swapper_space;
+        else
+#endif
+        if ((unsigned long)mapping & PAGE_MAPPING_ANON)
+                mapping = NULL;
+        return mapping;
+}
+
 /* Tracepoints definitions. */
 EXPORT_TRACEPOINT_SYMBOL(kmalloc);
 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc);