Re: [PATCH v8 01/10] fs: Allow fine-grained control of folio sizes

[Matthew Wilcox]

On Tue, Jul 09, 2024 at 04:29:07PM +0000, Pankaj Raghav (Samsung) wrote:
> +++ b/include/linux/pagemap.h
> @@ -394,13 +394,24 @@ static inline void mapping_set_folio_order_range(struct address_space *mapping,
>                                                  unsigned int min,
>                                                  unsigned int max)
>  {
> -       if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
> +       if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
> +               VM_WARN_ONCE(1, 
> +       "THP needs to be enabled to support mapping folio order range");
>                 return;
> +       }

No.  Filesystems call mapping_set_folio_order_range() without it being
conditional on CONFIG_TRANSPARENT_HUGEPAGE.  Usually that takes the
form of an unconditional call to mapping_set_large_folios().