Custom interrupt handler for the NMI hardware button

Question

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 <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <asm/nmi.h>

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 <[email protected]>");
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?