Re: [PATCH v3 0/4] Implement IOCTL to get and clear soft dirty PTE

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Oct 18, 2022 at 03:36:24PM +0500, Muhammad Usama Anjum wrote:
> /**
>  * struct pagemap_sd_args - Soft-dirty IOCTL argument
>  * @start:		Starting address
>  * @len:		Length of the region
>  * @vec:		Output page_region struct array
>  * @vec_len:		Length of the page_region struct array
>  * @max_out_page:	Optional max output pages (It must be less than vec_len if
> specified)
>  * @flags:		Special flags for the IOCTL
>  * @rmask:		Special flags for the IOCTL
>  * @amask:		Special flags for the IOCTL
>  * @emask:		Special flags for the IOCTL

What do you mean exactly by "special flags"?

>  * @__reserved:		Reserved member to preserve data alignment. Must be 0.
>  */
> struct pagemap_sd_args {
> 	__u64 __user start;
> 	__u64 len;
> 	__u64 __user vec; // page_region

__user is a marking for a pointer, not a u64, right?  Now the fact that
you treat it like a pointer later in the kernel is different, but that
shouldn't be on the uapi header file.  You can put it in the kerneldoc,
which you did not do.

thanks,

greg k-h