1 files changed, 31 insertions, 0 deletions

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 84374d8cf814..6cd0a8f90dc7 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -723,6 +723,37 @@ int free_swap_and_cache(swp_entry_t entry)
         return p != NULL;
 }
 
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR
+/**
+ * mem_cgroup_count_swap_user - count the user of a swap entry
+ * @ent: the swap entry to be checked
+ * @pagep: the pointer for the swap cache page of the entry to be stored
+ *
+ * Returns the number of the user of the swap entry. The number is valid only
+ * for swaps of anonymous pages.
+ * If the entry is found on swap cache, the page is stored to pagep with
+ * refcount of it being incremented.
+ */
+int mem_cgroup_count_swap_user(swp_entry_t ent, struct page **pagep)
+{
+        struct page *page;
+        struct swap_info_struct *p;
+        int count = 0;
+
+        page = find_get_page(&swapper_space, ent.val);
+        if (page)
+                count += page_mapcount(page);
+        p = swap_info_get(ent);
+        if (p) {
+                count += swap_count(p->swap_map[swp_offset(ent)]);
+                spin_unlock(&swap_lock);
+        }
+
+        *pagep = page;
+        return count;
+}
+#endif
+
 #ifdef CONFIG_HIBERNATION
 /*
  * Find the swap type that corresponds to given device (if any).