diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 6690e8b..413284a 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1287,6 +1287,8 @@
 						unsigned long long);
 	int (*revalidate_disk) (struct gendisk *);
 	int (*getgeo)(struct block_device *, struct hd_geometry *);
+	/* this callback is with swap_lock and sometimes page table lock held */
+	void (*swap_slot_free_notify) (struct block_device *, unsigned long);
 	struct module *owner;
 };