Re: [RFC PATCH 01/11] mm: khugepaged: add khugepaged_max_ptes_none check in collapse_file()

[Dev Jain]

On 20/08/25 2:37 pm, Baolin Wang wrote:
> Similar to the anonymous folios collapse, we should also check the 'khugepaged_max_ptes_none'
> when trying to collapse shmem/file folios.
>
> Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
> ---
>   mm/khugepaged.c | 7 +++++++
>   1 file changed, 7 insertions(+)
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 5a3386043f39..5d4493b77f3c 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -2125,6 +2125,13 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
>   					}
>   				}
>   				nr_none++;
> +
> +				if (cc->is_khugepaged && nr_none > khugepaged_max_ptes_none) {
> +					result = SCAN_EXCEED_NONE_PTE;
> +					count_vm_event(THP_SCAN_EXCEED_NONE_PTE);
> +					goto xa_locked;
> +				}
> +
>   				index++;
>   				continue;
>   			}

Isn't this already being checked in collapse_scan_file(), in the block
if (cc->is_khugepaged && present < HPAGE_PMD_NR - khugepaged_max_ptes_none)?