diff --git a/kernel/exit.c b/kernel/exit.c
index 2913b35..09b81da 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1678,6 +1678,29 @@ void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
 				TASK_INTERRUPTIBLE, 1, p);
 }
 
+static void debug_dump(void)
+{
+	struct task_struct *tsk = current;
+	struct task_struct *p;
+
+	if (strcmp(current->comm, "gdb"))
+		return;
+
+	printk("gdb is going to sleep ...\n");
+	
+	printk("gdb children list:\n");
+	read_lock(&tasklist_lock);
+	list_for_each_entry(p, &tsk->children, sibling)
+		printk("    pid=%d, exit_state=%d, exit_signal=%d\n",
+			p->pid, p->exit_state, p->exit_signal);
+
+	printk("gdb ptrace list:\n");
+	list_for_each_entry(p, &tsk->ptraced, ptrace_entry)
+		printk("    pid=%d, exit_state=%d, exit_signal=%d\n",
+			p->pid, p->exit_state, p->exit_signal);
+	read_unlock(&tasklist_lock);
+}
+
 static long do_wait(struct wait_opts *wo)
 {
 	struct task_struct *tsk;
@@ -1722,6 +1745,7 @@ notask:
 	if (!retval && !(wo->wo_flags & WNOHANG)) {
 		retval = -ERESTARTSYS;
 		if (!signal_pending(current)) {
+			debug_dump();
 			schedule();
 			goto repeat;
 		}
@@ -1815,6 +1839,9 @@ SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
 			__WNOTHREAD|__WCLONE|__WALL))
 		return -EINVAL;
 
+	if (!strcmp(current->comm, "gdb"))
+		printk("gdb wait for pid=%d\n", upid);
+
 	if (upid == -1)
 		type = PIDTYPE_MAX;
 	else if (upid < 0) {