--- old/src/hotspot/share/gc/g1/g1CollectedHeap.cpp	2019-06-07 13:19:20.931518841 +0200
+++ new/src/hotspot/share/gc/g1/g1CollectedHeap.cpp	2019-06-07 13:19:20.619508957 +0200
@@ -4658,7 +4658,7 @@
 
   bool const during_im = collector_state()->in_initial_mark_gc();
   if (during_im && allocated_bytes > 0) {
-    _cm->root_regions()->add(alloc_region);
+    _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
   }
   _hr_printer.retire(alloc_region);
 }