--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -470,11 +470,12 @@ struct action_data {
 	 * When a histogram trigger is hit, the values of any
 	 * references to variables, including variables being passed
 	 * as parameters to synthetic events, are collected into a
-	 * var_ref_vals array.  This var_ref_idx is the index of the
-	 * first param in the array to be passed to the synthetic
-	 * event invocation.
+	 * var_ref_vals array.  This var_ref_idx array is an array of
+	 * indices into the var_ref_vals array, one for each synthetic
+	 * event param, and is passed to the synthetic event
+	 * invocation.
 	 */
-	unsigned int		var_ref_idx;
+	unsigned int		var_ref_idx[TRACING_MAP_VARS_MAX];
 	struct synth_event	*synth_event;
 	bool			use_trace_keyword;
 	char			*synth_event_name;
@@ -875,14 +876,14 @@ static struct trace_event_functions synt
 
 static notrace void trace_event_raw_event_synth(void *__data,
 						u64 *var_ref_vals,
-						unsigned int var_ref_idx)
+						unsigned int *var_ref_idx)
 {
 	struct trace_event_file *trace_file = __data;
 	struct synth_trace_event *entry;
 	struct trace_event_buffer fbuffer;
 	struct ring_buffer *buffer;
 	struct synth_event *event;
-	unsigned int i, n_u64;
+	unsigned int i, n_u64, val_idx;
 	int fields_size = 0;
 
 	event = trace_file->event_call->data;
@@ -905,15 +906,16 @@ static notrace void trace_event_raw_even
 		goto out;
 
 	for (i = 0, n_u64 = 0; i < event->n_fields; i++) {
+		val_idx = var_ref_idx[i];
 		if (event->fields[i]->is_string) {
-			char *str_val = (char *)(long)var_ref_vals[var_ref_idx + i];
+			char *str_val = (char *)(long)var_ref_vals[val_idx];
 			char *str_field = (char *)&entry->fields[n_u64];
 
 			strscpy(str_field, str_val, STR_VAR_LEN_MAX);
 			n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
 		} else {
 			struct synth_field *field = event->fields[i];
-			u64 val = var_ref_vals[var_ref_idx + i];
+			u64 val = var_ref_vals[val_idx];
 
 			switch (field->size) {
 			case 1:
@@ -1113,10 +1115,10 @@ static struct tracepoint *alloc_synth_tr
 }
 
 typedef void (*synth_probe_func_t) (void *__data, u64 *var_ref_vals,
-				    unsigned int var_ref_idx);
+				    unsigned int *var_ref_idx);
 
 static inline void trace_synth(struct synth_event *event, u64 *var_ref_vals,
-			       unsigned int var_ref_idx)
+			       unsigned int *var_ref_idx)
 {
 	struct tracepoint *tp = event->tp;
 
@@ -2655,6 +2657,22 @@ static int init_var_ref(struct hist_fiel
 	goto out;
 }
 
+static int find_var_ref_idx(struct hist_trigger_data *hist_data,
+			    struct hist_field *var_field)
+{
+	struct hist_field *ref_field;
+	int i;
+
+	for (i = 0; i < hist_data->n_var_refs; i++) {
+		ref_field = hist_data->var_refs[i];
+		if (ref_field->var.idx == var_field->var.idx &&
+		    ref_field->var.hist_data == var_field->hist_data)
+			return i;
+	}
+
+	return -ENOENT;
+}
+
 /**
  * create_var_ref - Create a variable reference and attach it to trigger
  * @hist_data: The trigger that will be referencing the variable
@@ -4228,11 +4246,11 @@ static int trace_action_create(struct hi
 	struct trace_array *tr = hist_data->event_file->tr;
 	char *event_name, *param, *system = NULL;
 	struct hist_field *hist_field, *var_ref;
-	unsigned int i, var_ref_idx;
+	unsigned int i;
 	unsigned int field_pos = 0;
 	struct synth_event *event;
 	char *synth_event_name;
-	int ret = 0;
+	int var_ref_idx, ret = 0;
 
 	lockdep_assert_held(&event_mutex);
 
@@ -4249,8 +4267,6 @@ static int trace_action_create(struct hi
 
 	event->ref++;
 
-	var_ref_idx = hist_data->n_var_refs;
-
 	for (i = 0; i < data->n_params; i++) {
 		char *p;
 
@@ -4299,6 +4315,14 @@ static int trace_action_create(struct hi
 				goto err;
 			}
 
+			var_ref_idx = find_var_ref_idx(hist_data, var_ref);
+			if (WARN_ON(var_ref_idx < 0)) {
+				ret = var_ref_idx;
+				goto err;
+			}
+
+			data->var_ref_idx[i] = var_ref_idx;
+
 			field_pos++;
 			kfree(p);
 			continue;
@@ -4317,7 +4341,6 @@ static int trace_action_create(struct hi
 	}
 
 	data->synth_event = event;
-	data->var_ref_idx = var_ref_idx;
  out:
 	return ret;
  err:
