--- x/kernel/ucount.c
+++ y/kernel/ucount.c
@@ -149,11 +149,18 @@ static void hlist_add_ucounts(struct uco
 
 struct ucounts *get_ucounts(struct ucounts *ucounts)
 {
-	if (ucounts && atomic_add_negative(1, &ucounts->count)) {
-		put_ucounts(ucounts);
-		ucounts = NULL;
+	int count;
+
+	if (!ucounts)
+		return NULL;
+
+	count = atomic_read(&ucounts->count);
+
+	while (count > 0 && count + 1 > count) {
+		if (atomic_try_cmpxchg(&ucounts->count, &count, count + 1))
+			return ucounts;
 	}
-	return ucounts;
+	return NULL;
 }
 
 struct ucounts *alloc_ucounts(struct user_namespace *ns, kuid_t uid)
@@ -184,8 +191,8 @@ struct ucounts *alloc_ucounts(struct use
 			return new;
 		}
 	}
-	spin_unlock_irq(&ucounts_lock);
 	ucounts = get_ucounts(ucounts);
+	spin_unlock_irq(&ucounts_lock);
 	return ucounts;
 }