Re: [PATCH v3 09/40] docs: filesystems: update mmap_prepare docs for discontig kernel pgs

[Zi Yan]

On Thu Sep 17, 2026 at 12:22 PM EDT, Lorenzo Stoakes (ARM) wrote:
> Describe the newly introduced discontiguous kernel page mapping mechanism,
> detailing how to use it sensibly and how the API looks.
>
> Explicitly detail the various discontiguous actions available and how to
> use them.
>
> Signed-off-by: Lorenzo Stoakes (ARM) <ljs@xxxxxxxxxx>
> ---
>  Documentation/filesystems/mmap_prepare.rst | 81 ++++++++++++++++++++++++++++++
>  1 file changed, 81 insertions(+)
>
<snip>

> +* ``discontig_kernel_map_page()`` - Maps a single page, correctly handling
> +  compound pages (if the compound page is bigger than the remaining pages in the
> +  VMA, then only those pages that fit will be mapped). For a compound page, the
> +  head page must be passed.
> +* ``discontig_kernel_map_page_range()`` - Map an array of pages of a specified
> +  size. Note that if the number of pages specified exceeds the VMA size then an
> +  error will arise.

Why do mapping a compound page and a page range have different behaviors
on the bound? Either both do partial mappings or give errors when a
given input cannot be mapped as a whole in the VMA.



-- 
Best Regards,
Yan, Zi