struct data{
    struct data *next;
    struct msghdr *msg;
    size_t len;
}

struct data *head = NULL;

void add_to_end(struct data *newData){
    struct data *temp1;
    if (head == NULL){
        head = (struct data *)kmalloc(sizeof(struct data),GFP_KERNEL);
        head = newData;
    } else {
        temp1 = (struct data *)kmalloc(sizeof(struct data),GFP_KERNEL);
        temp1 = head;
        while(temp1->next!=NULL) {
            temp1 = temp->next;
        }
        temp1->next = newData;
    }
}

struct data *temp;

temp = (struct data *)kmalloc(sizeof(struct data),GFP_KERNEL);
temp->next = NULL;
temp->msg = (struct msghdr *)kmalloc(sizeof(struct msghdr),GFP_KERNEL);
temp->msg = message;
temp->len = length;
add_to_end(temp);

temp->msg = (struct msghdr *)kmalloc(sizeof(struct msghdr),GFP_KERNEL);
    // temp->msg = message;
    memcpy(temp->msg, message, sizeof(struct msghdr));

DEFINE_RAW_SPINLOCK(mylock);
    LIST_HEAD(vm_list);

    ....
    my_function() {
            ....
        raw_spin_lock(&kvm_lock);
        list_for_each_entry(kvm, &vm_list, vm_list)
            *val += *(u32 *)((void *)kvm + offset);
        raw_spin_unlock(&kvm_lock);

     }

head = (struct data *)kmalloc(sizeof(struct data),GFP_KERNEL);
    head = newData;