failed experiment: build "Hello World" kernel module for Raspberry Pi

It is a failed experiment to build "Hello World" kernel module for Raspberry Pi, follow the step:

• Run with a new installed Raspbian, wheezy, 2014-01-07.
• Download and transfer the source code of Raspberry Pi
• Create hello.c and Makefile follow "The Linux Kernel Module Programming Guide", 2.3. Hello World (part 2).
  
  hello.c
  

  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/init.h>
  
  static int __init hello_init(void)
  { 
   printk(KERN_INFO "Hello Raspberry Pi!\n");
   return 0;
  }
  
  static void __exit hello_exit(void)
  {
   printk(KERN_INFO "Bye Raspberry Pi!\n");
  }
  
  module_init(hello_init);
  module_exit(hello_exit);
  

  
  Makefile
  

  obj-m += hello.o
  
  all:
   make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
  
  clean:
   make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
  

  
  
• Then make it, without error.
• When I try to insert the module hello.ko, error of invalid module format reported.
  $ sudo insmod ./hello.ko
  Error: could not insert module ./hello.ko: Invalid module format
  
  
  
  
• "disagrees about version of symbol module_layout" logged in /var/log/messages'. I assume it is something mis-match between the kernel version in my source and the running system.
• Then I update Raspberry Pi to most update with:
  $ sudo rpi-update
  $ sudo apt-get update
  $ sudo apt-get upgrade
  and reboot
• I try to insmod again, but fail with "Unable to handle NULL pointer dereference at virtual address 00000004", and the system hang-up.

  

  "Unable to handle NULL pointer dereference at virtual address 00000004"

I'm a newbies in Linux programming, and ask for help. Please leave me comment for any advice.

Related:
- Half success, half fail experiment, cross compile kernel module for Raspberry Pi on Ubuntu