--- old/src/share/vm/code/nmethod.cpp	2013-08-14 16:14:19.799432337 +0200
+++ new/src/share/vm/code/nmethod.cpp	2013-08-14 16:14:19.527432342 +0200
@@ -1302,6 +1302,13 @@
   methodHandle the_method(method());
   No_Safepoint_Verifier nsv;
 
+  // during patching, depending on the nmethod state we must notify the GC that
+  // code has been unloaded, unregistering it. We cannot do this right while
+  // holding the Patching_lock because we need to use the CodeCache_lock. This
+  // would be prone to deadlocks.
+  // This flag is used to remember whether we need to later lock and unregister.
+  bool nmethod_needs_unregister = false;
+
   {
     // invalidate osr nmethod before acquiring the patching lock since
     // they both acquire leaf locks and we don't want a deadlock.
@@ -1334,10 +1341,11 @@
       inc_decompile_count();
     }
 
-    // If the state is becoming a zombie, unregister the nmethod with heap
+    // If the state is becoming a zombie, signal to unregister the nmethod with
+    // the heap.
     // This nmethod may have already been unloaded during a full GC.
     if ((state == zombie) && !is_unloaded()) {
-      Universe::heap()->unregister_nmethod(this);
+      nmethod_needs_unregister = true;
     }
 
     // Change state
@@ -1375,6 +1383,9 @@
       // safepoint can sneak in, otherwise the oops used by the
       // dependency logic could have become stale.
       MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
+      if (nmethod_needs_unregister) {
+        Universe::heap()->unregister_nmethod(this);
+      }
       flush_dependencies(NULL);
     }
 
@@ -1838,7 +1849,8 @@
 // oops.
 void nmethod::oops_do(OopClosure* f, bool do_strong_roots_only) {
   // make sure the oops ready to receive visitors
-  assert(!is_zombie() && !is_unloaded(),
+  assert(NMethodSweeper::is_sweeping(this) || is_marked_for_deoptimization() ||
+         (!is_zombie() && !is_unloaded()),
          "should not call follow on zombie or unloaded nmethod");
 
   // If the method is not entrant or zombie then a JMP is plastered over the