linux-kernel - Re: [PATCH v7 03/12] khugepaged: generalize hugepage_vma

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Message-ID: <469db7d1-ba99-4dc7-af13-b5fe850d4031@linux.alibaba.com>
Date: Fri, 23 May 2025 14:55:34 +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: david@...hat.com, ziy@...dia.com, lorenzo.stoakes@...cle.com,
 Liam.Howlett@...cle.com, ryan.roberts@....com, dev.jain@....com,
 corbet@....net, rostedt@...dmis.org, mhiramat@...nel.org,
 mathieu.desnoyers@...icios.com, akpm@...ux-foundation.org,
 baohua@...nel.org, willy@...radead.org, peterx@...hat.com,
 wangkefeng.wang@...wei.com, usamaarif642@...il.com, sunnanyong@...wei.com,
 vishal.moola@...il.com, thomas.hellstrom@...ux.intel.com,
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Subject: Re: [PATCH v7 03/12] khugepaged: generalize hugepage_vma_revalidate
 for mTHP support



On 2025/5/15 11:22, Nico Pache wrote:
> For khugepaged to support different mTHP orders, we must generalize this
> to check if the PMD is not shared by another VMA and the order is
> enabled.
> 
> No functional change in this patch.
> 
> Reviewed-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
> Co-developed-by: Dev Jain <dev.jain@....com>
> Signed-off-by: Dev Jain <dev.jain@....com>
> Signed-off-by: Nico Pache <npache@...hat.com>
> ---
>   mm/khugepaged.c | 10 +++++-----
>   1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 5457571d505a..0c4d6a02d59c 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -920,7 +920,7 @@ static int khugepaged_find_target_node(struct collapse_control *cc)
>   static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
>   				   bool expect_anon,
>   				   struct vm_area_struct **vmap,
> -				   struct collapse_control *cc)
> +				   struct collapse_control *cc, int order)
>   {
>   	struct vm_area_struct *vma;
>   	unsigned long tva_flags = cc->is_khugepaged ? TVA_ENFORCE_SYSFS : 0;
> @@ -934,7 +934,7 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
>   
>   	if (!thp_vma_suitable_order(vma, address, PMD_ORDER))

Sorry, I missed this before. Should we also change 'PMD_ORDER' to 
'order' for the thp_vma_suitable_order()?

>   		return SCAN_ADDRESS_RANGE;
> -	if (!thp_vma_allowable_order(vma, vma->vm_flags, tva_flags, PMD_ORDER))
> +	if (!thp_vma_allowable_order(vma, vma->vm_flags, tva_flags, order))
>   		return SCAN_VMA_CHECK;
>   	/*
>   	 * Anon VMA expected, the address may be unmapped then
> @@ -1130,7 +1130,7 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address,
>   		goto out_nolock;
>   
>   	mmap_read_lock(mm);
> -	result = hugepage_vma_revalidate(mm, address, true, &vma, cc);
> +	result = hugepage_vma_revalidate(mm, address, true, &vma, cc, HPAGE_PMD_ORDER);
>   	if (result != SCAN_SUCCEED) {
>   		mmap_read_unlock(mm);
>   		goto out_nolock;
> @@ -1164,7 +1164,7 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address,
>   	 * mmap_lock.
>   	 */
>   	mmap_write_lock(mm);
> -	result = hugepage_vma_revalidate(mm, address, true, &vma, cc);
> +	result = hugepage_vma_revalidate(mm, address, true, &vma, cc, HPAGE_PMD_ORDER);
>   	if (result != SCAN_SUCCEED)
>   		goto out_up_write;
>   	/* check if the pmd is still valid */
> @@ -2782,7 +2782,7 @@ int madvise_collapse(struct vm_area_struct *vma, struct vm_area_struct **prev,
>   			mmap_read_lock(mm);
>   			mmap_locked = true;
>   			result = hugepage_vma_revalidate(mm, addr, false, &vma,
> -							 cc);
> +							 cc, HPAGE_PMD_ORDER);
>   			if (result  != SCAN_SUCCEED) {
>   				last_fail = result;
>   				goto out_nolock;