Re: [PATCH v4 52/66] mm/ksm: Use maple tree iterators instead of vma linked list

From: Vlastimil Babka
Date: Wed Jan 19 2022 - 12:59:05 EST


On 12/1/21 15:30, Liam Howlett wrote:
> From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>

Acked-by: Vlastimil Babka <vbabka@xxxxxxx>

> ---
> mm/ksm.c | 19 ++++++++++++-------
> 1 file changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/mm/ksm.c b/mm/ksm.c
> index 0662093237e4..d309249c95a4 100644
> --- a/mm/ksm.c
> +++ b/mm/ksm.c
> @@ -973,11 +973,13 @@ static int unmerge_and_remove_all_rmap_items(void)
> struct mm_slot, mm_list);
> spin_unlock(&ksm_mmlist_lock);
>
> - for (mm_slot = ksm_scan.mm_slot;
> - mm_slot != &ksm_mm_head; mm_slot = ksm_scan.mm_slot) {
> + for (mm_slot = ksm_scan.mm_slot; mm_slot != &ksm_mm_head;
> + mm_slot = ksm_scan.mm_slot) {
> + MA_STATE(mas, &mm_slot->mm->mm_mt, 0, 0);

VMA_ITERATOR would be a bit shorter.

> +
> mm = mm_slot->mm;
> mmap_read_lock(mm);
> - for (vma = mm->mmap; vma; vma = vma->vm_next) {
> + mas_for_each(&mas, vma, ULONG_MAX) {
> if (ksm_test_exit(mm))
> break;
> if (!(vma->vm_flags & VM_MERGEABLE) || !vma->anon_vma)
> @@ -2226,6 +2228,7 @@ static struct rmap_item *scan_get_next_rmap_item(struct page **page)
> struct vm_area_struct *vma;
> struct rmap_item *rmap_item;
> int nid;
> + MA_STATE(mas, NULL, 0, 0);
>
> if (list_empty(&ksm_mm_head.mm_list))
> return NULL;
> @@ -2283,13 +2286,14 @@ static struct rmap_item *scan_get_next_rmap_item(struct page **page)
> }
>
> mm = slot->mm;
> + mas.tree = &mm->mm_mt;
> + mas_set(&mas, ksm_scan.address);
> +
> mmap_read_lock(mm);
> if (ksm_test_exit(mm))
> - vma = NULL;
> - else
> - vma = find_vma(mm, ksm_scan.address);
> + goto no_vmas;
>
> - for (; vma; vma = vma->vm_next) {
> + mas_for_each(&mas, vma, ULONG_MAX) {
> if (!(vma->vm_flags & VM_MERGEABLE))
> continue;
> if (ksm_scan.address < vma->vm_start)
> @@ -2327,6 +2331,7 @@ static struct rmap_item *scan_get_next_rmap_item(struct page **page)
> }
>
> if (ksm_test_exit(mm)) {
> +no_vmas:
> ksm_scan.address = 0;
> ksm_scan.rmap_list = &slot->rmap_list;
> }