Re: [PATCH v2 4/6] mm: drop HIGHPTE support altogether

["Lorenzo Stoakes (ARM)" <ljs@kernel.org>]

On Thu, Nov 12, 2026 at 12:25:26PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> With both x86 and arm having dropped CONFIG_HIGHPTE support, no
> architecture is left using it, so remove the remnants in common code.
>
> It is likely that further cleanups are possible in the page table
> code but those are not obvious from the config options.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

LGTM assuming Mike's changes :)

Acked-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>

> ---
>  include/linux/hugetlb.h | 5 +----
>  include/linux/mm.h      | 1 -
>  include/linux/pgtable.h | 9 ---------
>  3 files changed, 1 insertion(+), 14 deletions(-)
>
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index 58f755e70e96..7c6d191fdf50 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -178,7 +178,6 @@ void hugetlb_bootmem_set_nodes(void);
>
>  /* arch callbacks */
>
> -#ifndef CONFIG_HIGHPTE
>  /*
>   * pte_offset_huge() and pte_alloc_huge() are helpers for those architectures
>   * which may go down to the lowest PTE level in their huge_pte_offset() and
> @@ -193,7 +192,6 @@ static inline pte_t *pte_alloc_huge(struct mm_struct *mm, pmd_t *pmd,
>  {
>  	return pte_alloc(mm, pmd) ? NULL : pte_offset_huge(pmd, address);
>  }
> -#endif
>
>  pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
>  			unsigned long addr, unsigned long sz);
> @@ -1047,9 +1045,8 @@ static inline spinlock_t *huge_pte_lockptr(struct hstate *h,
>  	 */
>  	if (size >= PUD_SIZE)
>  		return pud_lockptr(mm, (pud_t *) pte);
> -	else if (size >= PMD_SIZE || IS_ENABLED(CONFIG_HIGHPTE))
> +	else if (size >= PMD_SIZE)
>  		return pmd_lockptr(mm, (pmd_t *) pte);
> -	/* pte_alloc_huge() only applies with !CONFIG_HIGHPTE */
>  	return ptep_lockptr(mm, pte);
>  }
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 6af3b7008f1a..019de55bd796 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -4025,7 +4025,6 @@ static inline spinlock_t *pte_lockptr(struct mm_struct *mm, pmd_t *pmd)
>
>  static inline spinlock_t *ptep_lockptr(struct mm_struct *mm, pte_t *pte)
>  {
> -	BUILD_BUG_ON(IS_ENABLED(CONFIG_HIGHPTE));
>  	BUILD_BUG_ON(MAX_PTRS_PER_PTE * sizeof(pte_t) > PAGE_SIZE);
>  	return ptlock_ptr(virt_to_ptdesc(pte));
>  }
> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> index 780fe849ff8b..1352b4cee7ae 100644
> --- a/include/linux/pgtable.h
> +++ b/include/linux/pgtable.h
> @@ -100,14 +100,6 @@ static inline pte_t *pte_offset_kernel(pmd_t *pmd, unsigned long address)
>  #define pte_offset_kernel pte_offset_kernel
>  #endif
>
> -#ifdef CONFIG_HIGHPTE
> -#define __pte_map(pmd, address) \
> -	((pte_t *)kmap_local_page(pmd_page(*(pmd))) + pte_index((address)))
> -#define pte_unmap(pte)	do {	\
> -	kunmap_local((pte));	\
> -	rcu_read_unlock();	\
> -} while (0)
> -#else
>  static inline pte_t *__pte_map(pmd_t *pmd, unsigned long address)
>  {
>  	return pte_offset_kernel(pmd, address);
> @@ -116,7 +108,6 @@ static inline void pte_unmap(pte_t *pte)
>  {
>  	rcu_read_unlock();
>  }
> -#endif
>
>  void pte_free_defer(struct mm_struct *mm, pgtable_t pgtable);
>
> --
> 2.53.0
>

--
Cheers, Lorenzo