On Wed, Jan 08, 2025 at 04:18:41PM +0000, Lorenzo Stoakes wrote:
> +++ b/include/linux/rmap.h
> @@ -754,6 +754,26 @@ unsigned long page_address_in_vma(const struct folio *folio,
> */
> int folio_mkclean(struct folio *);
>
> +/**
The kerneldoc comment should be with the implementation, not the
prototype.
> + * rmap_wrprotect_file_page() - Traverses the reverse mapping, finding all VMAs
> + * which contain a shared mapping of the single page at PFN @pfn in @mapping at
> + * offset @pgoff and write-protecting the mappings.
After the '-' should come a _short_ description ... maybe "Write protect
all mappings of this page".
> + * The PFN mapped does not have to be a folio, but rather can be a kernel
> + * allocation that is mapped into userland. We therefore do not require that the
> + * PFN maps to a folio with a valid mapping or index field, rather these are
> + * specified in @mapping and @pgoff.
> + *
> + * @mapping: The mapping whose reverse mapping should be traversed.
> + * @pgoff: The page offset at which @pfn is mapped within @mapping.
> + * @nr_pages: The number of physically contiguous base pages spanned.
> + * @pfn: The PFN of the memory mapped in @mapping at @pgoff.
The description of the params comes between the short and full
description of the function.
> + * Return the number of write-protected PTEs, or an error.
colon after Return: so it becomes a section.
> +int rmap_wrprotect_file_page(struct address_space *mapping, pgoff_t pgoff,
> + unsigned long nr_pages, unsigned long pfn)
> +{
> + struct wrprotect_file_state state = {
> + .cleaned = 0,
> + .pgoff = pgoff,
> + .pfn = pfn,
> + .nr_pages = nr_pages,
> + };
> + struct rmap_walk_control rwc = {
> + .arg = (void *)&state,
> + .rmap_one = rmap_wrprotect_file_one,
> + .invalid_vma = invalid_mkclean_vma,
> + };
> +
> + if (!mapping)
> + return 0;
Should it be valid to pass in NULL?
