On Fri, Jan 29, 2021 at 04:29:02PM +0100, Miroslav Benes wrote:

quoted

 
-	mutex_lock(&module_mutex);
+	rcu_read_lock_sched();
 	/*
 	 * We do not want to block removal of patched modules and therefore
 	 * we do not take a reference here. The patches are removed by

@@ -74,7 +75,7 @@ static void klp_find_object_module(struct klp_object *obj)
 	if (mod && mod->klp_alive)

RCU always baffles me a bit, so I'll ask. Don't we need 
rcu_dereference_sched() here? "mod" comes from a RCU-protected list, so I 
wonder.

rcu_dereference* is only used for dereferencing points where that
reference itself is RCU protected, that is the lookup of mod itself down
in find_module_all in this case.