8257999: Parallel GC crash in gc/parallel/TestDynShrinkHeap.java: new region is not in covered_region

Reviewed-by: sjohanss, tschatzl

src/hotspot/share/gc/parallel/psOldGen.cpp

@@ -35,6 +35,7 @@
 #include "logging/log.hpp"
 #include "oops/oop.inline.hpp"
 #include "runtime/java.hpp"
+#include "runtime/orderAccess.hpp"
 #include "utilities/align.hpp"
 
 PSOldGen::PSOldGen(ReservedSpace rs, size_t initial_size, size_t min_size,
@@ -380,7 +381,9 @@ void PSOldGen::post_resize() {
   WorkGang* workers = Thread::current()->is_VM_thread() ?
                       &ParallelScavengeHeap::heap()->workers() : NULL;
 
-  // ALWAYS do this last!!
+  // Ensure the space bounds are updated and made visible to other
+  // threads after the other data structures have been resized.
+  OrderAccess::storestore();
   object_space()->initialize(new_memregion,
                              SpaceDecorator::DontClear,
                              SpaceDecorator::DontMangle,