Re: [PATCH v1 06/10] mm/huge_memory: remove folio split check for READ_ONLY_THP_FOR_FS

Lorenzo Stoakes (Oracle)
2026-03-27T12:50:39Z

On Thu, Mar 26, 2026 at 09:42:51PM -0400, Zi Yan wrote:
> Without READ_ONLY_THP_FOR_FS, large file-backed folios cannot be created by
> a FS without large folio support. The check is no longer needed.
>
> Signed-off-by: Zi Yan <ziy@nvidia.com>

Seems legitimate, so:

Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>

> ---
> mm/huge_memory.c | 22 ----------------------
> 1 file changed, 22 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 1da1467328a3..30eddcbf86f1 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -3732,28 +3732,6 @@ int folio_check_splittable(struct folio *folio, unsigned int new_order,
> /* order-1 is not supported for anonymous THP. */
> if (new_order == 1)
> return -EINVAL;
> - } else if (split_type == SPLIT_TYPE_NON_UNIFORM || new_order) {
> - if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) &&
> - !mapping_large_folio_support(folio->mapping)) {
> - /*
> - * We can always split a folio down to a single page
> - * (new_order == 0) uniformly.
> - *
> - * For any other scenario
> - * a) uniform split targeting a large folio
> - * (new_order > 0)
> - * b) any non-uniform split
> - * we must confirm that the file system supports large
> - * folios.
> - *
> - * Note that we might still have THPs in such
> - * mappings, which is created from khugepaged when
> - * CONFIG_READ_ONLY_THP_FOR_FS is enabled. But in that
> - * case, the mapping does not actually support large
> - * folios properly.
> - */
> - return -EINVAL;
> - }
> }
>
> /*
> --
> 2.43.0
>