--- old/src/share/vm/gc/shenandoah/shenandoahHeap.inline.hpp	2016-12-19 17:24:26.923567856 +0100
+++ new/src/share/vm/gc/shenandoah/shenandoahHeap.inline.hpp	2016-12-19 17:24:26.844568853 +0100
@@ -252,6 +252,14 @@
     alloc_from_gclab = false;
   }
 
+#ifdef ASSERT
+  // Checking that current Java thread does not hold Threads_lock when we get here.
+  // If that ever be the case, we'd deadlock in oom_during_evacuation.
+  if ((! Thread::current()->is_GC_task_thread()) && (! Thread::current()->is_ConcurrentGC_thread())) {
+    assert(! Threads_lock->owned_by_self(), "must not hold Threads_lock here");
+  }
+#endif
+
   if (filler == NULL) {
     oom_during_evacuation();
     // If this is a Java thread, it should have waited