linux-kernel - Re: [PATCH v4 04/12] khugepaged: generalize alloc_charge

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Message-ID: <977ef858-ea03-4ea7-9420-6275ecd6a40d@linux.alibaba.com>
Date: Wed, 23 Apr 2025 15:06:40 +0800
From: Baolin Wang <baolin.wang@...ux.alibaba.com>
To: Nico Pache <npache@...hat.com>, linux-mm@...ck.org,
 linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-trace-kernel@...r.kernel.org
Cc: akpm@...ux-foundation.org, corbet@....net, rostedt@...dmis.org,
 mhiramat@...nel.org, mathieu.desnoyers@...icios.com, david@...hat.com,
 baohua@...nel.org, ryan.roberts@....com, willy@...radead.org,
 peterx@...hat.com, ziy@...dia.com, wangkefeng.wang@...wei.com,
 usamaarif642@...il.com, sunnanyong@...wei.com, vishal.moola@...il.com,
 thomas.hellstrom@...ux.intel.com, yang@...amperecomputing.com,
 kirill.shutemov@...ux.intel.com, aarcange@...hat.com, raquini@...hat.com,
 dev.jain@....com, anshuman.khandual@....com, catalin.marinas@....com,
 tiwai@...e.de, will@...nel.org, dave.hansen@...ux.intel.com, jack@...e.cz,
 cl@...two.org, jglisse@...gle.com, surenb@...gle.com, zokeefe@...gle.com,
 hannes@...xchg.org, rientjes@...gle.com, mhocko@...e.com,
 rdunlap@...radead.org
Subject: Re: [PATCH v4 04/12] khugepaged: generalize alloc_charge_folio()



On 2025/4/17 08:02, Nico Pache wrote:
> From: Dev Jain <dev.jain@....com>
> 
> Pass order to alloc_charge_folio() and update mTHP statistics.
> 
> Co-developed-by: Nico Pache <npache@...hat.com>
> Signed-off-by: Nico Pache <npache@...hat.com>
> Signed-off-by: Dev Jain <dev.jain@....com>

LGTM.
Reviewed-by: Baolin Wang <baolin.wang@...ux.alibaba.com>

> ---
>   include/linux/huge_mm.h |  2 ++
>   mm/huge_memory.c        |  4 ++++
>   mm/khugepaged.c         | 17 +++++++++++------
>   3 files changed, 17 insertions(+), 6 deletions(-)
> 
> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> index f190998b2ebd..55b242335420 100644
> --- a/include/linux/huge_mm.h
> +++ b/include/linux/huge_mm.h
> @@ -123,6 +123,8 @@ 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 e97a97586478..7798c9284533 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(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);
> @@ -680,6 +682,8 @@ 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 54d7f43da69c..883e9a46359f 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -1074,21 +1074,26 @@ 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)
>   {
>   	gfp_t gfp = (cc->is_khugepaged ? alloc_hugepage_khugepaged_gfpmask() :
>   		     GFP_TRANSHUGE);
>   	int node = khugepaged_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_vm_event(THP_COLLAPSE_ALLOC_FAILED);
> +		count_mthp_stat(order, MTHP_STAT_COLLAPSE_ALLOC_FAILED);
>   		return SCAN_ALLOC_HUGE_PAGE_FAIL;
>   	}
>   
> -	count_vm_event(THP_COLLAPSE_ALLOC);
> +	if (order == HPAGE_PMD_ORDER)
> +		count_vm_event(THP_COLLAPSE_ALLOC);
> +	count_mthp_stat(order, MTHP_STAT_COLLAPSE_ALLOC);
> +
>   	if (unlikely(mem_cgroup_charge(folio, mm, gfp))) {

Nit: while we are at it, why not add a 
‘MTHP_STAT_COLLAPSE_CHARGE_FAILED’, which is the same as anonymous and 
shmem mTHP allocation?

>   		folio_put(folio);
>   		*foliop = NULL;
> @@ -1125,7 +1130,7 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address,
>   	 */
>   	mmap_read_unlock(mm);
>   
> -	result = alloc_charge_folio(&folio, mm, cc);
> +	result = alloc_charge_folio(&folio, mm, cc, HPAGE_PMD_ORDER);
>   	if (result != SCAN_SUCCEED)
>   		goto out_nolock;
>   
> @@ -1849,7 +1854,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
>   	VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem);
>   	VM_BUG_ON(start & (HPAGE_PMD_NR - 1));
>   
> -	result = alloc_charge_folio(&new_folio, mm, cc);
> +	result = alloc_charge_folio(&new_folio, mm, cc, HPAGE_PMD_ORDER);
>   	if (result != SCAN_SUCCEED)
>   		goto out;
>