Re: [PATCH v3 2/6] mm: mincore: remove special handling for VM_PFNMAP

["David Hildenbrand (Arm)" <david@kernel.org>]

On 7/17/26 10:13, Kefeng Wang wrote:
> As David pointed out, "it’s hard to believe that someone depends
> on pages in VM_PFNMAP to *not* be present", so remove the historical
> behavior that always reports VM_PFNMAP pages as non-resident.
> 
> Adding mincore_pud_range() allows the page table walker to traverse
> the full page table hierarchy without splitting a huge PUD, enabling
> much more precise identification of resident pages in PFNMAP VMAs.
> 
> Link: https://lore.kernel.org/linux-mm/0e619d71-1c3d-4534-8376-2982c7348c31@kernel.org/
> Suggested-by: David Hildenbrand (Arm) <david@kernel.org>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
>  mm/mincore.c | 24 ++++++++++++++++--------
>  1 file changed, 16 insertions(+), 8 deletions(-)
> 
> diff --git a/mm/mincore.c b/mm/mincore.c
> index 53b982803771..3fccaa5c96f8 100644
> --- a/mm/mincore.c
> +++ b/mm/mincore.c
> @@ -160,6 +160,21 @@ static int mincore_unmapped_range(unsigned long addr, unsigned long end,
>  	return 0;
>  }
>  
> +static int mincore_pud_range(pud_t *pudp, unsigned long addr, unsigned long end,

s/mincore_pud_range/mincore_pud_entry/

> +		struct mm_walk *walk)
> +{
> +	if (pud_is_huge(pudp_get(pudp))) {
> +		int nr = (end - addr) >> PAGE_SHIFT;

Could be const.

> +		unsigned char *vec = walk->private;

Might be able to just cast that as part of the memset.

> +
> +		memset(vec, 1, nr);
> +		walk->action = ACTION_CONTINUE;
> +		walk->private += nr;
> +	}
> +
> +	return 0;
> +}

With the rename

Acked-by: David Hildenbrand (Arm) <david@kernel.org>

-- 
Cheers,

David