--- a/src/hotspot/share/gc/g1/collectionSetChooser.cpp	Thu Jun 07 11:20:18 2018 +0200
+++ b/src/hotspot/share/gc/g1/collectionSetChooser.cpp	Thu Jun 07 11:20:30 2018 +0200
@@ -147,7 +147,7 @@
 void CollectionSetChooser::add_region(HeapRegion* hr) {
   assert(!hr->is_pinned(),
          "Pinned region shouldn't be added to the collection set (index %u)", hr->hrm_index());
-  assert(!hr->is_young(), "should not be young!");
+  assert(hr->is_old(), "should be old but is %s", hr->get_type_str());
   assert(hr->rem_set()->is_complete(),
          "Trying to add region %u to the collection set with incomplete remembered set", hr->hrm_index());
   _regions.append(hr);
@@ -185,7 +185,7 @@
 
 void CollectionSetChooser::set_region(uint index, HeapRegion* hr) {
   assert(regions_at(index) == NULL, "precondition");
-  assert(!hr->is_young(), "should not be young!");
+  assert(hr->is_old(), "should be old but is %s", hr->get_type_str());
   regions_at_put(index, hr);
   hr->calc_gc_efficiency();
 }
@@ -233,18 +233,19 @@
     _cset_updater(hrSorted, true /* parallel */, chunk_size) { }
 
   bool do_heap_region(HeapRegion* r) {
-    // Do we have any marking information for this region?
-    if (r->is_marked()) {
-      // We will skip any region that's currently used as an old GC
-      // alloc region (we should not consider those for collection
-      // before we fill them up).
-      if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
-        _cset_updater.add_region(r);
-      } else if (r->is_old()) {
-        // Can clean out the remembered sets of all regions that we did not choose but
-        // we created the remembered set for.
-        r->rem_set()->clear(true);
-      }
+    // We will skip any region that's currently used as an old GC
+    // alloc region (we should not consider those for collection
+    // before we fill them up).
+    if (_cset_updater.should_add(r) && !_g1h->is_old_gc_alloc_region(r)) {
+      _cset_updater.add_region(r);
+    } else if (r->is_old()) {
+      // Keep remembered sets for humongous regions, otherwise clean out remembered
+      // sets for old regions.
+      r->rem_set()->clear(true /* only_cardset */);
+    } else {
+      assert(!r->is_old() || !r->rem_set()->is_tracked(),
+             "Missed to clear unused remembered set of region %u (%s) that is %s",
+             r->hrm_index(), r->get_type_str(), r->rem_set()->get_state_str());
     }
     return false;
   }
@@ -280,11 +281,10 @@
 }
 
 bool CollectionSetChooser::should_add(HeapRegion* hr) const {
-  assert(hr->is_marked(), "pre-condition");
-  assert(!hr->is_young(), "should never consider young regions");
-  return !hr->is_pinned() &&
-          region_occupancy_low_enough_for_evac(hr->live_bytes()) &&
-          hr->rem_set()->is_complete();
+  return !hr->is_young() &&
+         !hr->is_pinned() &&
+         region_occupancy_low_enough_for_evac(hr->live_bytes()) &&
+         hr->rem_set()->is_complete();
 }
 
 void CollectionSetChooser::rebuild(WorkGang* workers, uint n_regions) {

--- a/src/hotspot/share/gc/g1/g1Policy.cpp	Thu Jun 07 11:20:18 2018 +0200
+++ b/src/hotspot/share/gc/g1/g1Policy.cpp	Thu Jun 07 11:20:30 2018 +0200
@@ -825,10 +825,10 @@
 
 size_t G1Policy::predict_bytes_to_copy(HeapRegion* hr) const {
   size_t bytes_to_copy;
-  if (hr->is_marked())
+  if (!hr->is_young()) {
     bytes_to_copy = hr->max_live_bytes();
-  else {
-    assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
+  } else {
+    assert(hr->age_in_surv_rate_group() != -1, "invariant");
     int age = hr->age_in_surv_rate_group();
     double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
     bytes_to_copy = (size_t) (hr->used() * yg_surv_rate);

--- a/src/hotspot/share/gc/g1/heapRegion.hpp	Thu Jun 07 11:20:18 2018 +0200
+++ b/src/hotspot/share/gc/g1/heapRegion.hpp	Thu Jun 07 11:20:30 2018 +0200
@@ -541,10 +541,6 @@
   // objects during evac failure handling.
   void note_self_forwarding_removal_end(size_t marked_bytes);
 
-  // Returns "false" iff no object in the region was allocated when the
-  // last mark phase ended.
-  bool is_marked() { return _prev_top_at_mark_start != bottom(); }
-
   void reset_during_compaction() {
     assert(is_humongous(),
            "should only be called for humongous regions");