Re: [PATCH 1/3] mm: mprotect: always skip dma pinned folio in prot_numa_skip()

[Sidhartha Kumar <sidhartha.kumar@oracle.com>]

On 10/13/25 8:15 AM, Kefeng Wang wrote:
> If the folio(even not CoW folio) is dma pinned, it can't be
> migrated, so always skip pinned folio to avoid a waste of cycles
> when folios migration.
> 
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>

Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>

> ---
>   mm/mprotect.c | 9 ++++++---
>   1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/mprotect.c b/mm/mprotect.c
> index 113b48985834..51a28781de9d 100644
> --- a/mm/mprotect.c
> +++ b/mm/mprotect.c
> @@ -136,9 +136,12 @@ static bool prot_numa_skip(struct vm_area_struct *vma, unsigned long addr,
>   	if (folio_is_zone_device(folio) || folio_test_ksm(folio))
>   		goto skip;
>   
> -	/* Also skip shared copy-on-write pages */
> -	if (is_cow_mapping(vma->vm_flags) &&
> -	    (folio_maybe_dma_pinned(folio) || folio_maybe_mapped_shared(folio)))
> +	/* Also skip shared copy-on-write folios */
> +	if (is_cow_mapping(vma->vm_flags) && folio_maybe_mapped_shared(folio))
> +		goto skip;
> +
> +	/* Folios are pinned and can't be migrated */
> +	if (folio_maybe_dma_pinned(folio))
>   		goto skip;
>   
>   	/*