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).
}
/*
- * increase reference count of swap entry by 1.
+ * Increase reference count of swap entry by 1.
+ * Returns 0 for success, or -ENOMEM if a swap_count_continuation is required
+ * but could not be atomically allocated. Returns 0, just as if it succeeded,
+ * if __swap_duplicate() fails for another reason (-EINVAL or -ENOENT), which
+ * might occur if a page table entry has got corrupted.
*/
int swap_duplicate(swp_entry_t entry)
{