diff -r 9a7135d0a309 -r 7386b3a385ac src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp
--- a/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp	Tue Dec 17 05:07:06 2019 +0000
+++ b/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp	Tue Dec 17 05:26:57 2019 +0000
@@ -869,6 +869,10 @@
   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();
 }
@@ -1955,6 +1959,8 @@
   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 foreground collection to determine
@@ -2768,6 +2774,7 @@
 
   _capacity_at_prologue = capacity();
   _used_at_prologue = used();
+  _cmsSpace->recalculate_used_stable();
 
   // Delegate to CMScollector which knows how to coordinate between
   // this and any other CMS generations that it is responsible for
@@ -2837,6 +2844,7 @@
   _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
@@ -3672,6 +3680,7 @@
     _collectorState = Marking;
   }
   SpecializationStats::print();
+  _cmsGen->cmsSpace()->recalculate_used_stable();
 }
 
 void CMSCollector::checkpointRootsInitialWork(bool asynch) {
@@ -5066,10 +5075,12 @@
                     Mutex::_no_safepoint_check_flag);
     assert(!init_mark_was_synchronous, "but that's impossible!");
     checkpointRootsFinalWork(asynch, clear_all_soft_refs, false);
+    _cmsGen->cmsSpace()->recalculate_used_stable();
   } else {
     // already have all the locks
     checkpointRootsFinalWork(asynch, clear_all_soft_refs,
                              init_mark_was_synchronous);
+    _cmsGen->cmsSpace()->recalculate_used_stable();
   }
   verify_work_stacks_empty();
   verify_overflow_empty();
@@ -6368,6 +6379,10 @@
       // 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;
     }
   } else {
@@ -6467,6 +6482,7 @@
     // Gather statistics on the young generation collection.
     collector()->stats().record_gc0_end(used());
   }
+  _cmsSpace->recalculate_used_stable();
 }
 
 CMSAdaptiveSizePolicy* ConcurrentMarkSweepGeneration::size_policy() {