--- old/src/hotspot/share/gc/g1/g1OopClosures.inline.hpp 2018-10-30 11:38:02.137985633 +0100 +++ new/src/hotspot/share/gc/g1/g1OopClosures.inline.hpp 2018-10-30 11:38:01.705972352 +0100 @@ -84,7 +84,8 @@ prefetch_and_push(p, obj); } else if (!HeapRegion::is_in_same_region(p, obj)) { handle_non_cset_obj_common(state, p, obj); - if (_scanning_in_young) { + assert(_scanning_in_young != Uninitialized, "Scan location has not been initialized."); + if (_scanning_in_young == True) { return; } _par_scan_state->enqueue_card_if_tracked(p, obj);