--- old/src/hotspot/share/gc/cms/concurrentMarkSweepGeneration.cpp	Fri Jun 28 13:57:43 2019
+++ new/src/hotspot/share/gc/cms/concurrentMarkSweepGeneration.cpp	Fri Jun 28 13:57:42 2019
@@ -692,6 +692,10 @@
   return _cmsSpace->max_alloc_in_words() * HeapWordSize;
 }
 
+size_t ConcurrentMarkSweepGeneration::used_stable() const {
+  return cmsSpace()->used_stable();
+}
+
 size_t ConcurrentMarkSweepGeneration::max_available() const {
   return free() + _virtual_space.uncommitted_size();
 }
@@ -1523,6 +1527,8 @@
   FreelistLocker z(this);
   MetaspaceGC::compute_new_size();
   _cmsGen->compute_new_size_free_list();
+  // recalculate CMS used space after CMS collection
+  _cmsGen->cmsSpace()->recalculate_used_stable();
 }
 
 // A work method used by the foreground collector to do
@@ -2051,6 +2057,7 @@
 
   _capacity_at_prologue = capacity();
   _used_at_prologue = used();
+  _cmsSpace->recalculate_used_stable();
 
   // We enable promotion tracking so that card-scanning can recognize
   // which objects have been promoted during this GC and skip them.
@@ -2123,6 +2130,7 @@
   _eden_chunk_index = 0;
 
   size_t cms_used   = _cmsGen->cmsSpace()->used();
+  _cmsGen->cmsSpace()->recalculate_used_stable();
 
   // update performance counters - this uses a special version of
   // update_counters() that allows the utilization to be passed as a
@@ -2816,6 +2824,8 @@
     rp->enable_discovery();
     _collectorState = Marking;
   }
+
+  _cmsGen->cmsSpace()->recalculate_used_stable();
 }
 
 void CMSCollector::checkpointRootsInitialWork() {
@@ -4177,6 +4187,7 @@
     MutexLocker y(bitMapLock(),
                   Mutex::_no_safepoint_check_flag);
     checkpointRootsFinalWork();
+    _cmsGen->cmsSpace()->recalculate_used_stable();
   }
   verify_work_stacks_empty();
   verify_overflow_empty();
@@ -5337,9 +5348,14 @@
     // further below.
     {
       CMSTokenSyncWithLocks ts(true, _cmsGen->freelistLock());
+      
       // Update heap occupancy information which is used as
       // input to soft ref clearing policy at the next gc.
       Universe::update_heap_info_at_gc();
+   
+      // recalculate CMS used space after CMS collection
+      _cmsGen->cmsSpace()->recalculate_used_stable();
+ 
       _collectorState = Resizing;
     }
   }
@@ -5428,6 +5444,7 @@
     // Gather statistics on the young generation collection.
     collector()->stats().record_gc0_end(used());
   }
+  _cmsSpace->recalculate_used_stable();
 }
 
 void CMSCollector::sweepWork(ConcurrentMarkSweepGeneration* old_gen) {