Custom interrupt handler for the NMI hardware button

I'm trying to create a custom interrupt handler for the NMI hardware button which exists on my motherboard. To test this functionality I've created this simple module: #include #include #include #include static int nmi_custom_handler(unsigned int val, struct pt_regs* regs) { pr_info("My custom NMI: 0x%x\n", val); return NMI_HANDLED; } static int __init nmi_handler_init(void) { pr_info("nmi_handler_init\n"); register_nmi_handler(NMI_UNKNOWN, nmi_custom_handler, 0, "my_custom_nmi"); return 0; } static void __exit nmi_handler_exit(void) { pr_info("nmi_handler_exit\n"); unregister_nmi_handler(NMI_UNKNOWN, "my_custom_nmi"); } module_init(nmi_handler_init); module_exit(nmi_handler_exit); MODULE_AUTHOR("Konstantin Aladyshev "); MODULE_LICENSE("GPL"); If I load this module and press NMI button one time, there will be "My custom NMI" message for every CPU core in my system. The same can be seen in the "/proc/interrupt" interface. NMI interrupt count increases from 0 to 1 for every CPU. But for some reason this works only once. Next button presses don't get logged by my module or the /proc interface. Why? What should I change to be able to use NMI hardware interrupt again?