* semid identifiers are not unique - find_alloc_undo may have
* allocated an undo structure, it was invalidated by an RMID
* and now a new array with received the same id. Check and fail.
- * This case can be detected checking un->semid. The existance of
+ * This case can be detected checking un->semid. The existence of
* "un" itself is guaranteed by rcu.
*/
error = -EIDRM;