--- old/src/cpu/x86/vm/c1_CodeStubs_x86.cpp	2015-07-27 12:11:17.667415686 +0300
+++ new/src/cpu/x86/vm/c1_CodeStubs_x86.cpp	2015-07-27 12:11:17.627415850 +0300
@@ -416,7 +416,8 @@
   int jmp_off = __ offset();
   __ jmp(_patch_site_entry);
   // Add enough nops so deoptimization can overwrite the jmp above with a call
-  // and not destroy the world.
+  // and not destroy the world. We cannot use fat nops here, since the concurrent
+  // code rewrite may transiently create the illegal instruction sequence.
   for (int j = __ offset() ; j < jmp_off + 5 ; j++ ) {
     __ nop();
   }