Sometimes it is useful to panic a linux machine, specially when testing various HA setups or kdump thingies.

I found that "echo c > /proc/sysrq-trigger" is not enough. It produces a kernel dump but the machine keeps running. So I went with the more "hardcore" option: a kernel module that calls panic(). The idea is described in Linux Crash Howto, but here it is upgraded for the 2.6 kernel.

** panic.c: **
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/init.h>
  
  static int __init enter_module(void)
  {
    panic("forcing kernel panic.\n");
    return 0;
  }
  
  static void __exit exit_module(void)
  {
  /* dead code here */
    printk("Bye!\n");
  }
  
  module_init(enter_module);
  module_exit(exit_module);
  
  MODULE_AUTHOR("John Doe");
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("Panic mode on!");


** Makefile: **
  obj-m += panic.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

Have kernel sources handy, put these two files in a directory of your liking and simply say "make". You're presented with a panic.ko, which you simply insmod to kill the machine.