Re: [PATCH v6 2/5] userfaultfd: add /dev/userfaultfd for fine grained access control

[Greg KH]

On Wed, Aug 17, 2022 at 02:47:25PM -0700, Axel Rasmussen wrote:
>  static int __init userfaultfd_init(void)
>  {
> +	WARN_ON(misc_register(&userfaultfd_misc));

Please no.

Spell this out and properly error out if there is an issue:
	int ret;

	ret = misc_register(&userfaultfd_misc);
	if (ret)
		return ret;

Handle issues properly, don't paper over them with WARN_ON().

thanks,

greg k-h