Re: [PATCH 2/5] mm/hugetlb: Remove prepare_hugepage_range()

Zi Yan
2025-06-13T15:13:57Z

On 13 Jun 2025, at 9:41, Peter Xu wrote:

> Only mips and loongarch implemented this API, however what it does was
> checking against stack overflow for either len or addr. That's already
> done in arch's arch_get_unmapped_area*() functions, hence not needed.
>
> It means the whole API is pretty much obsolete at least now, remove it
> completely.
>
> Cc: Huacai Chen <chenhuacai@kernel.org>
> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> Cc: Muchun Song <muchun.song@linux.dev>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: loongarch@lists.linux.dev
> Cc: linux-mips@vger.kernel.org
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
> arch/loongarch/include/asm/hugetlb.h | 14 --------------
> arch/mips/include/asm/hugetlb.h | 14 --------------
> fs/hugetlbfs/inode.c | 8 ++------
> include/asm-generic/hugetlb.h | 8 --------
> include/linux/hugetlb.h | 6 ------
> 5 files changed, 2 insertions(+), 48 deletions(-)
>
> diff --git a/arch/loongarch/include/asm/hugetlb.h b/arch/loongarch/include/asm/hugetlb.h
> index 4dc4b3e04225..ab68b594f889 100644
> --- a/arch/loongarch/include/asm/hugetlb.h
> +++ b/arch/loongarch/include/asm/hugetlb.h
> @@ -10,20 +10,6 @@
>
> uint64_t pmd_to_entrylo(unsigned long pmd_val);
>
> -#define __HAVE_ARCH_PREPARE_HUGEPAGE_RANGE
> -static inline int prepare_hugepage_range(struct file *file,
> - unsigned long addr,
> - unsigned long len)
> -{
> - unsigned long task_size = STACK_TOP;
> -
> - if (len > task_size)
> - return -ENOMEM;
> - if (task_size - len < addr)
> - return -EINVAL;
> - return 0;
> -}
> -
> #define __HAVE_ARCH_HUGE_PTE_CLEAR
> static inline void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
> pte_t *ptep, unsigned long sz)
> diff --git a/arch/mips/include/asm/hugetlb.h b/arch/mips/include/asm/hugetlb.h
> index fbc71ddcf0f6..8c460ce01ffe 100644
> --- a/arch/mips/include/asm/hugetlb.h
> +++ b/arch/mips/include/asm/hugetlb.h
> @@ -11,20 +11,6 @@
>
> #include <asm/page.h>
>
> -#define __HAVE_ARCH_PREPARE_HUGEPAGE_RANGE
> -static inline int prepare_hugepage_range(struct file *file,
> - unsigned long addr,
> - unsigned long len)
> -{
> - unsigned long task_size = STACK_TOP;
> -
> - if (len > task_size)
> - return -ENOMEM;

arch_get_unmapped_area_topdown() has this check.

> - if (task_size - len < addr)
> - return -EINVAL;

For this one, arch_get_unmapped_area_topdown() instead will try to
provide a different addr if the check fails.

So this patch changes the original code behavior, right?
If yes, it is worth spelling it out in the commit log.

Otherwise, Reviewed-by: Zi Yan <ziy@nvidia.com>

Best Regards,
Yan, Zi