Re: [PATCH v8 04/15] hugetlb: Mark some function arguments as const

On 7/31/2026 1:07 PM, Matthew Wilcox (Oracle) wrote:
> These functions do not modify their folio argument, so we can mark them=20
> as being const which will allow for some minor optimisations and let us=20
> mark other function arguments as being const in the future. Signed-off-=20
> by: Matthew Wilcox (Oracle)
>=20
>=20
> These functions do not modify their folio argument, so we can mark them
> as being const which will allow for some minor optimisations and let us
> mark other function arguments as being const in the future.
>=20
> Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
> Acked-by: Usama Arif <[email protected]>
> Reviewed-by: Gregory Price <[email protected]>
> Reviewed-by: Miaohe Lin <[email protected]>
> ---
>   include/linux/hugetlb.h | 19 +++++++++----------
>   mm/hugetlb.c            |  2 +-
>   2 files changed, 10 insertions(+), 11 deletions(-)
>=20
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index 50eab2c23299..e200c93088bc 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -176,7 +176,7 @@ bool hugetlbfs_pagecache_present(struct hstate *h,
>   				 struct vm_area_struct *vma,
>   				 unsigned long address);
>  =20
> -struct address_space *hugetlb_folio_mapping_lock_write(struct folio *fol=
io);
> +struct address_space *hugetlb_folio_mapping_lock_write(const struct foli=
o *folio);
>  =20
>   extern int movable_gigantic_pages __read_mostly;
>   extern int sysctl_hugetlb_shm_group __read_mostly;
> @@ -311,8 +311,7 @@ static inline unsigned long hugetlb_total_pages(void)
>   	return 0;
>   }
>  =20
> -static inline struct address_space *hugetlb_folio_mapping_lock_write(
> -							struct folio *folio)
> +static inline struct address_space *hugetlb_folio_mapping_lock_write(con=
st struct folio *folio)
>   {
>   	return NULL;
>   }
> @@ -614,8 +613,8 @@ enum hugetlb_page_flags {
>   #ifdef CONFIG_HUGETLB_PAGE
>   #define TESTHPAGEFLAG(uname, flname)				\
>   static __always_inline						\
> -bool folio_test_hugetlb_##flname(struct folio *folio)		\
> -	{	void *private =3D &folio->private;		\
> +bool folio_test_hugetlb_##flname(const struct folio *folio)	\
> +	{	const void *private =3D &folio->private;		\
>   		return test_bit(HPG_##flname, private);		\
>   	}
>  =20
> @@ -635,7 +634,7 @@ void folio_clear_hugetlb_##flname(struct folio *folio=
)		\
>   #else
>   #define TESTHPAGEFLAG(uname, flname)				\
>   static inline bool						\
> -folio_test_hugetlb_##flname(struct folio *folio)		\
> +folio_test_hugetlb_##flname(const struct folio *folio)		\
>   	{ return 0; }
>  =20
>   #define SETHPAGEFLAG(uname, flname)				\
> @@ -746,7 +745,7 @@ static inline struct hugepage_subpool *subpool_inode(=
struct inode *inode)
>   	return HUGETLBFS_SB(inode->i_sb)->spool;
>   }
>  =20
> -static inline struct hugepage_subpool *hugetlb_folio_subpool(struct foli=
o *folio)
> +static inline struct hugepage_subpool *hugetlb_folio_subpool(const struc=
t folio *folio)
>   {
>   	return folio->_hugetlb_subpool;
>   }
> @@ -876,7 +875,7 @@ static inline bool arch_has_huge_bootmem_alloc(void)
>   }
>   #endif
>  =20
> -static inline struct hstate *folio_hstate(struct folio *folio)
> +static inline struct hstate *folio_hstate(const struct folio *folio)
>   {
>   	VM_BUG_ON_FOLIO(!folio_test_hugetlb(folio), folio);
>   	return size_to_hstate(folio_size(folio));
> @@ -1107,7 +1106,7 @@ static inline unsigned long huge_page_mask_align(st=
ruct file *file)
>   	return 0;
>   }
>  =20
> -static inline struct hugepage_subpool *hugetlb_folio_subpool(struct foli=
o *folio)
> +static inline struct hugepage_subpool *hugetlb_folio_subpool(const struc=
t folio *folio)
>   {
>   	return NULL;
>   }
> @@ -1176,7 +1175,7 @@ static inline struct hstate *hstate_vma(struct vm_a=
rea_struct *vma)
>   	return NULL;
>   }
>  =20
> -static inline struct hstate *folio_hstate(struct folio *folio)
> +static inline struct hstate *folio_hstate(const struct folio *folio)
>   {
>   	return NULL;
>   }
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 571212b80835..cc8d98399913 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1775,7 +1775,7 @@ void init_new_hugetlb_folio(struct folio *folio)
>    * stable.  Due to locking order, we can only trylock_write.  If we can
>    * not get the lock, simply return NULL to caller.
>    */
> -struct address_space *hugetlb_folio_mapping_lock_write(struct folio *fol=
io)
> +struct address_space *hugetlb_folio_mapping_lock_write(const struct foli=
o *folio)
>   {
>   	struct address_space *mapping =3D folio_mapping(folio);
>  =20
> --=20
> 2.47.3
>=20

Reviewed-by: Jane Chu <[email protected]>

thanks,
-jane