Re: [PATCH v9 04/14] khugepaged: generalize alloc_charge_folio()

[David Hildenbrand <david@redhat.com>]

On 14.07.25 02:31, Nico Pache wrote:
> From: Dev Jain <dev.jain@arm.com>
> 
> Pass order to alloc_charge_folio() and update mTHP statistics.
> 
> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
> Co-developed-by: Nico Pache <npache@redhat.com>
> Signed-off-by: Nico Pache <npache@redhat.com>
> Signed-off-by: Dev Jain <dev.jain@arm.com>
> ---
>   Documentation/admin-guide/mm/transhuge.rst |  8 ++++++++
>   include/linux/huge_mm.h                    |  2 ++
>   mm/huge_memory.c                           |  4 ++++
>   mm/khugepaged.c                            | 17 +++++++++++------
>   4 files changed, 25 insertions(+), 6 deletions(-)
> 
> diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst
> index dff8d5985f0f..2c523dce6bc7 100644
> --- a/Documentation/admin-guide/mm/transhuge.rst
> +++ b/Documentation/admin-guide/mm/transhuge.rst
> @@ -583,6 +583,14 @@ anon_fault_fallback_charge
>   	instead falls back to using huge pages with lower orders or
>   	small pages even though the allocation was successful.
>   
> +collapse_alloc
> +	is incremented every time a huge page is successfully allocated for a
> +	khugepaged collapse.
> +
> +collapse_alloc_failed
> +	is incremented every time a huge page allocation fails during a
> +	khugepaged collapse.
> +
>   zswpout
>   	is incremented every time a huge page is swapped out to zswap in one
>   	piece without splitting.
> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> index 7748489fde1b..4042078e8cc9 100644
> --- a/include/linux/huge_mm.h
> +++ b/include/linux/huge_mm.h
> @@ -125,6 +125,8 @@ enum mthp_stat_item {
>   	MTHP_STAT_ANON_FAULT_ALLOC,
>   	MTHP_STAT_ANON_FAULT_FALLBACK,
>   	MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE,
> +	MTHP_STAT_COLLAPSE_ALLOC,
> +	MTHP_STAT_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 bd7a623d7ef8..e2ed9493df77 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -614,6 +614,8 @@ 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(collapse_alloc, MTHP_STAT_COLLAPSE_ALLOC);
> +DEFINE_MTHP_STAT_ATTR(collapse_alloc_failed, MTHP_STAT_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);
> @@ -679,6 +681,8 @@ static struct attribute *any_stats_attrs[] = {
>   #endif
>   	&split_attr.attr,
>   	&split_failed_attr.attr,
> +	&collapse_alloc_attr.attr,
> +	&collapse_alloc_failed_attr.attr,
>   	NULL,
>   };
>   
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index fa0642e66790..cc9a35185604 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -1068,21 +1068,26 @@ 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)
> +			      struct collapse_control *cc, u8 order)

u8, really? :)

Just use an "unsigned int" like folio_order() would or what 
__folio_alloc() consumes.



Apart from that

Acked-by: David Hildenbrand <david@redhat.com>

-- 
Cheers,

David / dhildenb