*** old/src/cpu/x86/vm/macroAssembler_x86.cpp	Tue Nov  5 11:43:58 2013
--- new/src/cpu/x86/vm/macroAssembler_x86.cpp	Tue Nov  5 11:43:58 2013

*** 1379,1390 ****
--- 1379,1393 ----
    subptr(tmp, os::vm_page_size());
    subl(size, os::vm_page_size());
    jcc(Assembler::greater, loop);
  
    // Bang down shadow pages too.
!   // The -1 because we already subtracted 1 page.
    for (int i = 0; i< StackShadowPages-1; i++) {
!   // At this point, (tmp-0) is the last address touched, so don't touch it again.
+   // (It was touched as (tmp-pagesize) but then tmp was post-decremented.)
+   // Skip this address by starting at i=1, and touch a few more pages below.
+   // N.B.  It is important to touch all the down to and including i=StackShadowPages.
+   for (int i = 1; i <= StackShadowPages; i++) {
      // this could be any sized move but this is can be a debugging crumb
      // so the bigger the better.
      movptr(Address(tmp, (-i*os::vm_page_size())), size );
    }
  }