diff -ru trunk-orig/libgomp/oacc-async.c trunk-work/libgomp/oacc-async.c
--- trunk-orig/libgomp/oacc-async.c	2018-12-14 22:11:29.252251925 +0800
+++ trunk-work/libgomp/oacc-async.c	2018-12-18 22:19:51.923102938 +0800
@@ -70,12 +70,16 @@
 
   struct gomp_device_descr *dev = thr->dev;
 
+  gomp_mutex_lock (&dev->openacc.async.lock);
+
   if (!create
       && (async >= dev->openacc.async.nasyncqueue
 	  || !dev->openacc.async.asyncqueue[async]))
-    return NULL;
+    {
+      gomp_mutex_unlock (&dev->openacc.async.lock);
+      return NULL;
+    }
 
-  gomp_mutex_lock (&dev->openacc.async.lock);
   if (async >= dev->openacc.async.nasyncqueue)
     {
       int diff = async + 1 - dev->openacc.async.nasyncqueue;
@@ -91,6 +95,12 @@
     {
       dev->openacc.async.asyncqueue[async] = dev->openacc.async.construct_func ();
 
+      if (!dev->openacc.async.asyncqueue[async])
+	{
+	  gomp_mutex_unlock (&dev->openacc.async.lock);
+	  gomp_fatal ("async %d creation failed", async);
+	}
+      
       /* Link new async queue into active list.  */
       goacc_aq_list n = gomp_malloc (sizeof (struct goacc_asyncqueue_list));
       n->aq = dev->openacc.async.asyncqueue[async];
diff -ru trunk-orig/libgomp/oacc-host.c trunk-work/libgomp/oacc-host.c
--- trunk-orig/libgomp/oacc-host.c	2018-12-14 18:31:07.487203770 +0800
+++ trunk-work/libgomp/oacc-host.c	2018-12-18 22:23:26.771807667 +0800
@@ -266,6 +266,9 @@
 
       .exec_func = host_openacc_exec,
 
+      .create_thread_data_func = host_openacc_create_thread_data,
+      .destroy_thread_data_func = host_openacc_destroy_thread_data,
+
       .async = {
 	.construct_func = host_openacc_async_construct,
 	.destruct_func = host_openacc_async_destruct,
@@ -278,9 +281,6 @@
 	.host2dev_func = host_openacc_async_host2dev,
       },
 
-      .create_thread_data_func = host_openacc_create_thread_data,
-      .destroy_thread_data_func = host_openacc_destroy_thread_data,
-
       .cuda = {
 	.get_current_device_func = NULL,
 	.get_current_context_func = NULL,
diff -ru trunk-orig/libgomp/oacc-plugin.c trunk-work/libgomp/oacc-plugin.c
--- trunk-orig/libgomp/oacc-plugin.c	2018-12-14 18:31:07.491203745 +0800
+++ trunk-work/libgomp/oacc-plugin.c	2018-12-18 22:27:46.047722004 +0800
@@ -30,6 +30,13 @@
 #include "oacc-plugin.h"
 #include "oacc-int.h"
 
+void
+GOMP_PLUGIN_async_unmap_vars (void *ptr __attribute__((unused)),
+			      int async __attribute__((unused)))
+{
+  gomp_fatal ("invalid plugin function");
+}
+
 /* Return the target-specific part of the TLS data for the current thread.  */
 
 void *
diff -ru trunk-orig/libgomp/plugin/plugin-nvptx.c trunk-work/libgomp/plugin/plugin-nvptx.c