--- a/src/share/vm/gc_implementation/shenandoah/shenandoahBarrierSet.cpp	Fri Jan 16 23:59:37 2015 +0100
+++ b/src/share/vm/gc_implementation/shenandoah/shenandoahBarrierSet.cpp	Mon Jan 19 17:31:19 2015 +0100
@@ -277,6 +277,11 @@
 
 oop ShenandoahBarrierSet::resolve_and_maybe_copy_oop_work2(oop src) {
   ShenandoahHeap *sh = (ShenandoahHeap*) Universe::heap();
+  if (! sh->is_evacuation_in_progress()) {
+    // We may get here through a barrier that just took a safepoint that
+    // turned off evacuation. In this case, return right away.
+    return ShenandoahBarrierSet::resolve_oop_static(src);
+  }
   assert(src != NULL, "only evacuated non NULL oops");
   assert(sh->heap_region_containing(src)->is_in_collection_set(), "only evacuate objects in collection set");
   assert(! sh->heap_region_containing(src)->is_humonguous(), "never evacuate humonguous objects");

--- a/src/share/vm/gc_implementation/shenandoah/shenandoahHeap.cpp	Fri Jan 16 23:59:37 2015 +0100
+++ b/src/share/vm/gc_implementation/shenandoah/shenandoahHeap.cpp	Mon Jan 19 17:31:19 2015 +0100
@@ -1074,8 +1074,6 @@
 
 void ShenandoahHeap::prepare_for_concurrent_evacuation() {
 
-  _cancelled_evacuation = false;
-
   if (! ShenandoahUpdateRefsEarly) {
     recycle_dirty_regions();
   }
@@ -1166,7 +1164,7 @@
     ShenandoahHeapRegion* region = _regions->claim_next();
     ShenandoahHeap* heap = ShenandoahHeap::heap();
     while (region != NULL) {
-      if (! ((region->is_in_collection_set() && ! heap->cancelled_evacuation()) || region->is_humonguous_continuation())) {
+      if ((! region->is_in_collection_set() || heap->cancelled_evacuation()) && ! region->is_humonguous_continuation()) {
         HeapWord* failed = region->object_iterate_careful(&update_refs_cl);
         assert(failed == NULL, "careful iteration is implemented safe for now in Shenandaoh");
       }
@@ -1489,6 +1487,8 @@
     if (forwarded_oop != heap_oop) {
       // tty->print_cr("updating old ref: %p pointing to %p to new ref: %p", p, heap_oop, forwarded_oop);
       assert(forwarded_oop->is_oop(), "oop required");
+      assert(is_in(forwarded_oop), "forwardee must be in heap");
+      assert(! heap_region_containing(forwarded_oop)->is_in_collection_set(), "forwardee must not be in collection set");
       // If this fails, another thread wrote to p before us, it will be logged in SATB and the
       // reference be updated later.
       oop result = (oop) Atomic::cmpxchg_ptr(forwarded_oop, p, heap_oop);
@@ -2337,7 +2337,6 @@
     // until all GC threads are done, and then we
     // return the forwardee.
     oop resolved = ShenandoahBarrierSet::resolve_oop_static(p);
-    tty->print_cr("possible emergency allocation needed: %p", (oopDesc*) resolved);
     return resolved;
   }