diff -r ba42fd5e00e6 -r 7b835924c31c src/share/vm/gc_implementation/g1/concurrentMark.cpp
--- a/src/share/vm/gc_implementation/g1/concurrentMark.cpp	Wed Apr 10 13:27:35 2013 +0200
+++ b/src/share/vm/gc_implementation/g1/concurrentMark.cpp	Wed Apr 10 14:26:49 2013 +0200
@@ -101,6 +101,10 @@
 }
 #endif
 
+void CMBitMapRO::print_on_error(outputStream* st, const char* prefix) const {
+  _bm.print_on_error(st, prefix);
+}
+
 bool CMBitMap::allocate(ReservedSpace heap_rs) {
   _bmStartWord = (HeapWord*)(heap_rs.base());
   _bmWordSize  = heap_rs.size()/HeapWordSize;    // heap_rs.size() is in bytes
@@ -3277,6 +3281,13 @@
   }
 }
 
+void ConcurrentMark::print_on_error(outputStream* st) const {
+  st->print_cr("Marking Bits (Prev, Next): (CMBitMap*) " PTR_FORMAT ", (CMBitMap*) " PTR_FORMAT,
+      _prevMarkBitMap, _nextMarkBitMap);
+  _prevMarkBitMap->print_on_error(st, " Prev Bits: ");
+  _nextMarkBitMap->print_on_error(st, " Next Bits: ");
+}
+
 // We take a break if someone is trying to stop the world.
 bool ConcurrentMark::do_yield_check(uint worker_id) {
   if (should_yield()) {