Re: [PATCH 1/8] mm/khugepaged: refactor per-scan state clearing into collapse_control_init_scan()

[Usama Arif <usama.arif@linux.dev>]

On Mon,  6 Jul 2026 09:44:48 -0600 Nico Pache <npache@redhat.com> wrote:

> Extract the repeated clearing of node_load, alloc_nmask, and
> mthp_present_ptes into a helper to reduce duplication in
> collapse_scan_pmd() and collapse_scan_file(). Althought file scans do not
> current use the bitmap, they will in the future, and clearing it now is
> harmless.
> 
> Signed-off-by: Nico Pache <npache@redhat.com>
> ---
>  mm/khugepaged.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
> 
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 617bca76db49..b3985b854e77 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -628,6 +628,17 @@ void __khugepaged_exit(struct mm_struct *mm)
>  	}
>  }
>  
> +/*
> + * collapse_control_init_scan() - initialize/reset collapse_control variables
> + * that require being cleared once per-scan.
> + */

Probably don't need the above comment, but apart from that

Acked-by: Usama Arif <usama.arif@linux.dev>

> +static void collapse_control_init_scan(struct collapse_control *cc)
> +{
> +	memset(cc->node_load, 0, sizeof(cc->node_load));
> +	nodes_clear(cc->alloc_nmask);
> +	bitmap_zero(cc->mthp_present_ptes, MAX_PTRS_PER_PTE);
> +}
> +
>  static void release_pte_folio(struct folio *folio)
>  {
>  	node_stat_mod_folio(folio,
> @@ -1616,9 +1627,7 @@ static enum scan_result collapse_scan_pmd(struct mm_struct *mm,
>  		goto out;
>  	}
>  
> -	bitmap_zero(cc->mthp_present_ptes, MAX_PTRS_PER_PTE);
> -	memset(cc->node_load, 0, sizeof(cc->node_load));
> -	nodes_clear(cc->alloc_nmask);
> +	collapse_control_init_scan(cc);
>  
>  	enabled_orders = collapse_possible_orders(vma, vma->vm_flags, tva_flags);
>  
> @@ -2686,8 +2695,7 @@ static enum scan_result collapse_scan_file(struct mm_struct *mm,
>  
>  	present = 0;
>  	swap = 0;
> -	memset(cc->node_load, 0, sizeof(cc->node_load));
> -	nodes_clear(cc->alloc_nmask);
> +	collapse_control_init_scan(cc);
>  	rcu_read_lock();
>  	xas_for_each(&xas, folio, start + HPAGE_PMD_NR - 1) {
>  		if (xas_retry(&xas, folio))
> -- 
> 2.54.0
> 
>