diff --git a/Makefile b/Makefile
index 1c6214f..767dd84 100644
--- a/Makefile
+++ b/Makefile
@@ -1,10 +1,11 @@
 KDIR=/mnt/mainline
 #KDIR=/usr/src/kernels/$(shell uname -r)
 
-obj-m += demo.o
-obj-m += blk_kprobe.o
-obj-m += kobject-example.o
-obj-m += kprobe_trace.o
+#obj-m += demo.o
+#obj-m += blk_kprobe.o
+#obj-m += kobject-example.o
+#obj-m += kprobe_trace.o
+obj-m += lockup.o
 
 all:
 	make -C $(KDIR) M=$(shell pwd) modules
diff --git a/kprobe_trace.c b/kprobe_trace.c
index 755607c..a001155 100644
--- a/kprobe_trace.c
+++ b/kprobe_trace.c
@@ -17,6 +17,7 @@ void test_func2(struct test_struct p);
 
 void test_func1(struct test_struct *p)
 {
+	printk("%d\n", p->val);
 	printk("%s\n", p->name);
 	printk("%s\n", p->pname);
 	printk("%d\n", p->arr[1]);
@@ -25,6 +26,7 @@ void test_func1(struct test_struct *p)
 
 void test_func2(struct test_struct p)
 {
+	printk("%d\n", p.val);
 	printk("%s\n", p.name);
 	printk("%s\n", p.pname);
 	printk("%d\n", p.arr[1]);
diff --git a/lockup.c b/lockup.c
new file mode 100644
index 0000000..277b7b1
--- /dev/null
+++ b/lockup.c
@@ -0,0 +1,120 @@
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/cdev.h>
+#include <linux/workqueue.h>
+
+MODULE_LICENSE("GPL v2");
+
+static struct work_struct dwork;
+static struct workqueue_struct *wq;
+
+static void demo_work(struct work_struct * unused)
+{
+	int i = 0, j = 0;
+
+	// set_worker_desc("hwc");
+	printk("[cpu%d]: %s %d\n", raw_smp_processor_id(), __func__, __LINE__);
+	while(j < 2000) {
+		for (i = 0; i < 10000000; i++)
+			if (i % 100000 == 0)
+				printk("[cpu%d]: %s %d, i is %d, j is %d\n", raw_smp_processor_id(), __func__, __LINE__, i, j);
+
+		j++;
+	}
+}
+
+static ssize_t demo_read(struct file *filp, char __user *buff, size_t size, loff_t *pos)
+{
+	preempt_disable();
+	printk("[cpu%d]: %s %d\n", raw_smp_processor_id(), __func__, __LINE__);
+	while(1);
+	return size;
+}
+
+static ssize_t demo_write(struct file *filp, const char __user *buff, size_t size, loff_t *pos)
+{
+	printk("[cpu%d]: %s %d\n", raw_smp_processor_id(), __func__, __LINE__);
+	local_irq_disable();
+	while(1);
+	printk("[cpu%d]: %s %d\n", raw_smp_processor_id(), __func__, __LINE__);
+	
+	return size;
+}
+
+static int demo_open(struct inode *inode, struct file *filp)
+{
+	printk("%s %d\n", __func__, __LINE__);
+	return 0;
+}
+
+static int demo_release(struct inode *inode, struct file *filp)
+{
+	printk("%s %d\n", __func__, __LINE__);
+	return 0;
+}
+
+struct file_operations demo_fops = {
+	.owner      = THIS_MODULE,
+	.read       = demo_read,
+	.write      = demo_write,
+	.open       = demo_open,
+	.release    = demo_release,
+};
+
+static dev_t dev;
+static struct cdev *cdev;
+
+static int demo_init(void)
+{
+	int rc;
+
+	INIT_WORK(&dwork, demo_work);
+
+	rc = alloc_chrdev_region(&dev, 0, 1, "demo");
+	if (rc) {
+		printk("failed to alloc chrdev number\n");
+		return rc;
+	}
+
+	cdev = cdev_alloc();
+	if (!cdev) {
+		printk("failed to alloc cdev\n");
+		rc = -ENOMEM;
+		goto out_unregister_chrdev;
+	}
+
+	cdev->owner = THIS_MODULE;
+	cdev_init(cdev, &demo_fops);
+
+	rc = cdev_add(cdev, dev, 1);
+	if (rc) {
+		printk("failed to add char device\n");
+		goto out_free_cdev;
+	}
+
+	wq = create_workqueue("demo123456789abcdefghijklmnopq");
+
+	queue_work(wq, &dwork);
+
+	return 0;
+
+out_free_cdev:
+	kobject_put(&cdev->kobj);	
+
+out_unregister_chrdev:
+	unregister_chrdev_region(dev, 1);
+
+	return rc;
+}
+
+static void demo_exit(void)
+{
+	cdev_del(cdev);
+
+	unregister_chrdev_region(dev, 1);
+
+	destroy_workqueue(wq);
+}
+
+module_init(demo_init);
+module_exit(demo_exit);
diff --git a/mknod.sh b/mknod.sh
index 982b644..d9eb594 100755
--- a/mknod.sh
+++ b/mknod.sh
@@ -1,6 +1,6 @@
 #!/bin/sh
 
-major=$(cat /proc/devices  | grep demo)
+major=$(cat /proc/devices  | grep demo | awk '{print $1}')
 
-mknode /dev/demo c $major 0
+mknod /dev/demo c $major 0