diff -r 5743a702da65 -r 80ac3ee51955 src/share/vm/gc_implementation/g1/g1RemSet.cpp
--- a/src/share/vm/gc_implementation/g1/g1RemSet.cpp	Tue Mar 24 10:04:10 2015 +0000
+++ b/src/share/vm/gc_implementation/g1/g1RemSet.cpp	Wed Mar 25 11:03:16 2015 +0100
@@ -147,11 +147,9 @@
 
     // Set the "from" region in the closure.
     _oc->set_region(r);
-    HeapWord* card_start = _bot_shared->address_for_index(index);
-    HeapWord* card_end = card_start + G1BlockOffsetSharedArray::N_words;
-    Space *sp = SharedHeap::heap()->space_containing(card_start);
-    MemRegion sm_region = sp->used_region_at_save_marks();
-    MemRegion mr = sm_region.intersection(MemRegion(card_start,card_end));
+    MemRegion card_region(_bot_shared->address_for_index(index), G1BlockOffsetSharedArray::N_words);
+    MemRegion pre_gc_allocated(r->bottom(), r->scan_top());
+    MemRegion mr = pre_gc_allocated.intersection(card_region);
     if (!mr.is_empty() && !_ct_bs->is_card_claimed(index)) {
       // We make the card as "claimed" lazily (so races are possible
       // but they're benign), which reduces the number of duplicate