7099824: G1: we should take the pending list lock before doing the remark pause

Summary: Acquire the pending list lock in the prologue method of G1's concurrent VM_Operation and release the lock in the epilogue() method. The locking/unlocking order of the pending list lock and the Heap_lock should match that in the prologue and epilogue methods of VM_GC_Operation.
Reviewed-by: tonyp, ysr

1 files changed, 7 insertions, 1 deletions

diff --git a/src/share/vm/gc_implementation/g1/vm_operations_g1.hpp b/src/share/vm/gc_implementation/g1/vm_operations_g1.hpp
index 825818dd4..c8bbe0619 100644
--- a/src/share/vm/gc_implementation/g1/vm_operations_g1.hpp
+++ b/src/share/vm/gc_implementation/g1/vm_operations_g1.hpp
@@ -93,11 +93,17 @@ public:
   }
 };
 
-// Concurrent GC stop-the-world operations such as initial and final mark;
+// Concurrent GC stop-the-world operations such as remark and cleanup;
 // consider sharing these with CMS's counterparts.
 class VM_CGC_Operation: public VM_Operation {
   VoidClosure* _cl;
   const char* _printGCMessage;
+
+protected:
+  // java.lang.ref.Reference support
+  void acquire_pending_list_lock();
+  void release_and_notify_pending_list_lock();
+
 public:
   VM_CGC_Operation(VoidClosure* cl, const char *printGCMsg)
     : _cl(cl), _printGCMessage(printGCMsg) { }