Re: [PATCH v13 52/70] mm/khugepaged: stop using vma linked list

[Davidlohr Bueso]

On Mon, 22 Aug 2022, Liam Howlett wrote:

> From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
>
> Use vma iterator & find_vma() instead of vma linked list.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>

Reviewed-by: Davidlohr Bueso <dave@xxxxxxxxxxxx>

> ---
> mm/huge_memory.c |  4 ++--
> mm/khugepaged.c  | 11 ++++++++---
> 2 files changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 83c47a989260..6c5c23ef658a 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -2339,11 +2339,11 @@ 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 next vma vm_start,
> 	 * 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 d3313b7a8fe5..d8e388106322 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -2053,10 +2053,12 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result,
> 	__releases(&khugepaged_mm_lock)
> 	__acquires(&khugepaged_mm_lock)
> {
> +	struct vma_iterator vmi;
> 	struct mm_slot *mm_slot;
> 	struct mm_struct *mm;
> 	struct vm_area_struct *vma;
> 	int progress = 0;
> +	unsigned long address;

Nit: just use khugepaged_scan.address.

> 	VM_BUG_ON(!pages);
> 	lockdep_assert_held(&khugepaged_mm_lock);
> @@ -2081,11 +2083,14 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result,
> 	vma = NULL;
> 	if (unlikely(!mmap_read_trylock(mm)))
> 		goto breakouterloop_mmap_lock;
> -	if (likely(!hpage_collapse_test_exit(mm)))
> -		vma = find_vma(mm, khugepaged_scan.address);
>
> 	progress++;
> -	for (; vma; vma = vma->vm_next) {
> +	if (unlikely(hpage_collapse_test_exit(mm)))
> +		goto breakouterloop;
> +
> +	address = khugepaged_scan.address;
> +	vma_iter_init(&vmi, mm, address);
> +	for_each_vma(vmi, vma) {
> 		unsigned long hstart, hend;
>
> 		cond_resched();
>
> --
> 2.35.1