--- old/src/hotspot/share/gc/g1/g1ConcurrentMark.cpp	2018-04-19 00:46:37.218820834 -0400
+++ new/src/hotspot/share/gc/g1/g1ConcurrentMark.cpp	2018-04-19 00:46:36.990808900 -0400
@@ -1695,14 +1695,6 @@
     assert(!rp->discovery_enabled(), "Post condition");
   }
 
-  assert(has_overflown() || _global_mark_stack.is_empty(),
-         "Mark stack should be empty (unless it has overflown)");
-
-  {
-    GCTraceTime(Debug, gc, phases) debug("Weak Processing", _gc_timer_cm);
-    WeakProcessor::weak_oops_do(&g1_is_alive, &do_nothing_cl);
-  }
-
   if (has_overflown()) {
     // We can not trust g1_is_alive if the marking stack overflowed
     return;
@@ -1710,6 +1702,11 @@
 
   assert(_global_mark_stack.is_empty(), "Marking should have completed");
 
+  {
+    GCTraceTime(Debug, gc, phases) debug("Weak Processing", _gc_timer_cm);
+    WeakProcessor::weak_oops_do(&g1_is_alive, &do_nothing_cl);
+  }
+
   // Unload Klasses, String, Symbols, Code Cache, etc.
   if (ClassUnloadingWithConcurrentMark) {
     GCTraceTime(Debug, gc, phases) debug("Class Unloading", _gc_timer_cm);