diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 0892e38..a9dfa04 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -272,9 +272,11 @@ int perf_kprobe_init(struct perf_event *p_event, bool is_retprobe)
 		goto out;
 	}
 
+	mutex_lock(&event_mutex);
 	ret = perf_trace_event_init(tp_event, p_event);
 	if (ret)
 		destroy_local_trace_kprobe(tp_event);
+	mutex_unlock(&event_mutex);
 out:
 	kfree(func);
 	return ret;
@@ -282,8 +284,10 @@ out:
 
 void perf_kprobe_destroy(struct perf_event *p_event)
 {
+	mutex_lock(&event_mutex);
 	perf_trace_event_close(p_event);
 	perf_trace_event_unreg(p_event);
+	mutex_unlock(&event_mutex);
 
 	destroy_local_trace_kprobe(p_event->tp_event);
 }
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 57648c5..7482a14 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -679,6 +679,8 @@ static bool synth_field_signed(char *type)
 {
 	if (str_has_prefix(type, "u"))
 		return false;
+	if (strcmp(type, "gfp_t") == 0)
+		return false;
 
 	return true;
 }