Some more checking

Author: Thomas Schatzl

src/hotspot/share/gc/g1/g1CollectedHeap.cpp

@@ -2634,7 +2634,7 @@ void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
   assert(!hr->is_free(), "the region should not be free");
   assert(!hr->is_empty(), "the region should not be empty");
   assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
-  assert(!hr->has_pinned_objects(),
+  guarantee(!hr->has_pinned_objects(),
          "must not free a region which contains pinned objects");
 
   // Reset region metadata to allow reuse.