diff --git a/ChangeLog b/ChangeLog
index f2ce6678d3..272150d919 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Mon Jan 31 21:32:44 2011  CHIKANAGA Tomoyuki  <nagachika00@gmail.com>
+
+	* thread.c (thread_start_func_2): check deadlock condition before
+	  release thread stack. fix memory violation when deadlock detected.
+	  reported by Max Aller. [Bug #4009] [ruby-core:32982]
+
 Mon Jan 31 14:45:47 2011  Yuki Sonoda (Yugui)  <yugui@yugui.jp>
 
 	* lib/irb/locale.rb (IRB::Locale::#search_file):
diff --git a/thread.c b/thread.c
index 69fc299fcd..b1a802b89c 100644
--- a/thread.c
+++ b/thread.c
@@ -524,13 +524,14 @@ thread_start_func_2(rb_thread_t *th, VALUE *stack_start, VALUE *register_stack_s
 	    join_th = join_th->join_list_next;
 	}
 
+	thread_unlock_all_locking_mutexes(th);
+	if (th != main_th) rb_check_deadlock(th->vm);
+
 	if (!th->root_fiber) {
 	    rb_thread_recycle_stack_release(th->stack);
 	    th->stack = 0;
 	}
     }
-    thread_unlock_all_locking_mutexes(th);
-    if (th != main_th) rb_check_deadlock(th->vm);
     if (th->vm->main_thread == th) {
 	ruby_cleanup(state);
     }