diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 1688782f3dfb83f8442c751c11afca8b76654968..efd3c2bccf81413cb0b8aed873c8571878e75117 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -4208,10 +4208,13 @@ void free_ftrace_func_mapper(struct ftrace_func_mapper *mapper,
 	struct ftrace_func_entry *entry;
 	struct ftrace_func_map *map;
 	struct hlist_head *hhd;
-	int size = 1 << mapper->hash.size_bits;
-	int i;
+	int size, i;
+
+	if (!mapper)
+		return;
 
 	if (free_func && mapper->hash.count) {
+		size = 1 << mapper->hash.size_bits;
 		for (i = 0; i < size; i++) {
 			hhd = &mapper->hash.buckets[i];
 			hlist_for_each_entry(entry, hhd, hlist) {