Re: [PATCH v4 51/66] mm/khugepaged: Use maple tree iterators instead of vma linked list

[Vlastimil Babka]

On 12/1/21 15:30, Liam Howlett wrote:
> From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>

Ah, got tired of copy/pasting for a number of patches, I see :)

> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
> ---
>  mm/huge_memory.c | 4 ++--
>  mm/khugepaged.c  | 9 ++++++---
>  2 files changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index e5483347291c..f0f4ff5239ef 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -2270,11 +2270,11 @@ void vma_adjust_trans_huge(struct vm_area_struct *vma,
>  	split_huge_pmd_if_needed(vma, end);
>  
>  	/*
> -	 * If we're also updating the vma->vm_next->vm_start,
> +	 * If we're also updating the vma_next(vma)->vm_start,

vma_next() takes an iterator, not vma, though.

>  	 * check if we need to split it.
>  	 */
>  	if (adjust_next > 0) {
> -		struct vm_area_struct *next = vma->vm_next;
> +		struct vm_area_struct *next = find_vma(vma->vm_mm, vma->vm_end);
>  		unsigned long nstart = next->vm_start;
>  		nstart += adjust_next;
>  		split_huge_pmd_if_needed(next, nstart);
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 0ff7d72cdd1d..8f0633481791 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -2083,6 +2083,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
>  	struct mm_struct *mm;
>  	struct vm_area_struct *vma;
>  	int progress = 0;
> +	unsigned long address;
>  
>  	VM_BUG_ON(!pages);
>  	lockdep_assert_held(&khugepaged_mm_lock);
> @@ -2106,11 +2107,13 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
>  	vma = NULL;
>  	if (unlikely(!mmap_read_trylock(mm)))
>  		goto breakouterloop_mmap_lock;
> -	if (likely(!khugepaged_test_exit(mm)))
> -		vma = find_vma(mm, khugepaged_scan.address);
>  
>  	progress++;
> -	for (; vma; vma = vma->vm_next) {
> +	if (unlikely(khugepaged_test_exit(mm)))
> +		goto breakouterloop;
> +
> +	address = khugepaged_scan.address;
> +	mt_for_each(&mm->mm_mt, vma, address, ULONG_MAX) {

Why not via mas_for_each()?

>  		unsigned long hstart, hend;
>  
>  		cond_resched();