Re: [RFC PATCH 02/12] khugepaged: Generalize alloc_charge_folio()

[Baolin Wang]

On 2024/12/17 00:50, Dev Jain wrote:
> Pass order to alloc_charge_folio() and update mTHP statistics.
>
> Signed-off-by: Dev Jain <dev.jain@xxxxxxx>
> ---
>   include/linux/huge_mm.h |  2 ++
>   mm/huge_memory.c        |  4 ++++
>   mm/khugepaged.c         | 13 +++++++++----
>   3 files changed, 15 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> index 93e509b6c00e..8b6d0fed99b3 100644
> --- a/include/linux/huge_mm.h
> +++ b/include/linux/huge_mm.h
> @@ -119,6 +119,8 @@ enum mthp_stat_item {
>   	MTHP_STAT_ANON_FAULT_ALLOC,
>   	MTHP_STAT_ANON_FAULT_FALLBACK,
>   	MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE,
> +	MTHP_STAT_ANON_COLLAPSE_ALLOC,
> +	MTHP_STAT_ANON_COLLAPSE_ALLOC_FAILED,
>   	MTHP_STAT_ZSWPOUT,
>   	MTHP_STAT_SWPIN,
>   	MTHP_STAT_SWPIN_FALLBACK,
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 2da5520bfe24..2e582fad4c77 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -615,6 +615,8 @@ static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
>   DEFINE_MTHP_STAT_ATTR(anon_fault_alloc, MTHP_STAT_ANON_FAULT_ALLOC);
>   DEFINE_MTHP_STAT_ATTR(anon_fault_fallback, MTHP_STAT_ANON_FAULT_FALLBACK);
>   DEFINE_MTHP_STAT_ATTR(anon_fault_fallback_charge, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE);
> +DEFINE_MTHP_STAT_ATTR(anon_collapse_alloc, MTHP_STAT_ANON_COLLAPSE_ALLOC);
> +DEFINE_MTHP_STAT_ATTR(anon_collapse_alloc_failed, MTHP_STAT_ANON_COLLAPSE_ALLOC_FAILED);
>   DEFINE_MTHP_STAT_ATTR(zswpout, MTHP_STAT_ZSWPOUT);
>   DEFINE_MTHP_STAT_ATTR(swpin, MTHP_STAT_SWPIN);
>   DEFINE_MTHP_STAT_ATTR(swpin_fallback, MTHP_STAT_SWPIN_FALLBACK);
> @@ -636,6 +638,8 @@ static struct attribute *anon_stats_attrs[] = {
>   	&anon_fault_alloc_attr.attr,
>   	&anon_fault_fallback_attr.attr,
>   	&anon_fault_fallback_charge_attr.attr,
> +	&anon_collapse_alloc_attr.attr,
> +	&anon_collapse_alloc_failed_attr.attr,
>   #ifndef CONFIG_SHMEM
>   	&zswpout_attr.attr,
>   	&swpin_attr.attr,
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 95643e6e5f31..02cd424b8e48 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -1073,21 +1073,26 @@ static int __collapse_huge_page_swapin(struct mm_struct *mm,
>   }
>   
>   static int alloc_charge_folio(struct folio **foliop, struct mm_struct *mm,
> -			      struct collapse_control *cc)
> +			      int order, struct collapse_control *cc)
>   {
>   	gfp_t gfp = (cc->is_khugepaged ? alloc_hugepage_khugepaged_gfpmask() :
>   		     GFP_TRANSHUGE);
>   	int node = hpage_collapse_find_target_node(cc);
>   	struct folio *folio;
>   
> -	folio = __folio_alloc(gfp, HPAGE_PMD_ORDER, node, &cc->alloc_nmask);
> +	folio = __folio_alloc(gfp, order, node, &cc->alloc_nmask);
>   	if (!folio) {
>   		*foliop = NULL;
>   		count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
> +		if (order != HPAGE_PMD_ORDER)
> +			count_mthp_stat(order, MTHP_STAT_ANON_COLLAPSE_ALLOC_FAILED);
>   		return SCAN_ALLOC_HUGE_PAGE_FAIL;
>   	}
>   
>   	count_vm_event(THP_COLLAPSE_ALLOC);
> +	if (order != HPAGE_PMD_ORDER)
> +		count_mthp_stat(order, MTHP_STAT_ANON_COLLAPSE_ALLOC);

File collapse will also call alloc_charge_folio() to allocate THP, so 
using term '_ANON_' is not suitable for both anon and file collapse.