diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 410c336..ab933fe 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -3176,6 +3176,7 @@
 	list_del_rcu(&class->hash_entry);
 	list_del_rcu(&class->lock_entry);
 
+	class->key = NULL;
 }
 
 static inline int within(const void *addr, void *start, unsigned long size)
diff --git a/kernel/lockdep_proc.c b/kernel/lockdep_proc.c
index 6252ff7..fa19aee 100644
--- a/kernel/lockdep_proc.c
+++ b/kernel/lockdep_proc.c
@@ -201,6 +201,9 @@
 
 	for (i = 0; i < chain->depth; i++) {
 		class = lock_chain_get_class(chain, i);
+		if (!class->key)
+			continue;
+
 		seq_printf(m, "[%p] ", class->key);
 		print_name(m, class);
 		seq_puts(m, "\n");