hello_world: loading out-of-tree module taints kernel. hello_world: module verification failed: sign

@kevinpaul468 If you're seeing your output from the init and exit functions in dmesg at the same time, it's usually because you're not adding a newline character at the end of your printk(). It has nothing to do with the signing. Make sure you include a '\n', like this:

pr_info("foo\n");

Even from userspace, this still happens:

echo -n test | sudo tee /dev/kmsg > /dev/null && sudo dmesg | tail -1 | grep test # nothing shows up
echo test | sudo tee /dev/kmsg > /dev/null && sudo dmesg | tail -2 | grep test # both "test" messages get printed out

Why? Simply because messages without a trailing newline can be continued, just like when you call pr_cont(). This behavior is managed by the vprintk_store() function:

    /* A message without a trailing newline can be continued. */
    if (!(flags & LOG_NEWLINE))
        prb_commit(&e);
    else
        prb_final_commit(&e);