kmalloc_test.c

#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/moduleparam.h>
#include <asm/io.h>

static void *virtual_addr;
static phys_addr_t physical_addr;
int size = 1024; /* allocate 1024 bytes */

static int alloc_init(void)
{
    virtual_addr = kmalloc(size,GFP_ATOMIC);

    if(!virtual_addr) {
        /* handle error */
        pr_err("memory allocation failed\n");
        return -ENOMEM;
    } else {
        pr_info("Memory allocated successfully Virtual address:%p\n", virtual_addr);
		physical_addr = virt_to_phys(virtual_addr);
		pr_info("Physical address:%llx\n", physical_addr);
		pr_info("Virtual address:%p\n", phys_to_virt(physical_addr));
    }

    return 0;
}

static void alloc_exit(void)
{
    kfree(virtual_addr);
    pr_info("Memory freed\n");
}

module_init(alloc_init);
module_exit(alloc_exit);
MODULE_LICENSE("GPL");