--- old/src/cpu/x86/vm/macroAssembler_x86.cpp	2013-09-09 10:14:24.681343310 +0200
+++ new/src/cpu/x86/vm/macroAssembler_x86.cpp	2013-09-09 10:14:24.581341472 +0200
@@ -3388,9 +3388,14 @@
   const Register card_addr = tmp;
   lea(card_addr, as_Address(ArrayAddress(cardtable, index)));
 #endif
-  cmpb(Address(card_addr, 0), 0);
+  cmpb(Address(card_addr, 0), (int)CardTableModRefBS::g1_young_card_val());
   jcc(Assembler::equal, done);
 
+  membar(Assembler::Membar_mask_bits(Assembler::StoreLoad));
+  cmpb(Address(card_addr, 0), (int)CardTableModRefBS::dirty_card_val());
+  jcc(Assembler::equal, done);
+
+
   // storing a region crossing, non-NULL oop, card is clean.
   // dirty card and log.