2022-08-22 15:08:51

by Liam R. Howlett

Subject: [PATCH v13 10/70] mmap: use the VMA iterator in count_vma_pages_range()

From: "Matthew Wilcox (Oracle)" <[email protected]>

This simplifies the implementation and is faster than using the linked
list.

Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Signed-off-by: Liam R. Howlett <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
---
mm/mmap.c | 24 +++++++-----------------
1 file changed, 7 insertions(+), 17 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 20718645d82f..f1b07751a1e4 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -629,29 +629,19 @@ munmap_vma_range(struct mm_struct *mm, unsigned long start, unsigned long len,

return 0;
}
+
static unsigned long count_vma_pages_range(struct mm_struct *mm,
unsigned long addr, unsigned long end)
{
- unsigned long nr_pages = 0;
+ VMA_ITERATOR(vmi, mm, addr);
struct vm_area_struct *vma;
+ unsigned long nr_pages = 0;

- /* Find first overlapping mapping */
- vma = find_vma_intersection(mm, addr, end);
- if (!vma)
- return 0;
-
- nr_pages = (min(end, vma->vm_end) -
- max(addr, vma->vm_start)) >> PAGE_SHIFT;
-
- /* Iterate over the rest of the overlaps */
- for (vma = vma->vm_next; vma; vma = vma->vm_next) {
- unsigned long overlap_len;
-
- if (vma->vm_start > end)
- break;
+ for_each_vma_range(vmi, vma, end) {
+ unsigned long vm_start = max(addr, vma->vm_start);
+ unsigned long vm_end = min(end, vma->vm_end);

- overlap_len = min(end, vma->vm_end) - vma->vm_start;
- nr_pages += overlap_len >> PAGE_SHIFT;
+ nr_pages += PHYS_PFN(vm_end - vm_start);
}

return nr_pages;
--
2.35.1

2022-08-31 03:05:43

by Davidlohr Bueso

Subject: Re: [PATCH v13 10/70] mmap: use the VMA iterator in count_vma_pages_range()

On Mon, 22 Aug 2022, Liam Howlett wrote:

>From: "Matthew Wilcox (Oracle)" <[email protected]>
>
>This simplifies the implementation and is faster than using the linked
>list.
>
>Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
>Signed-off-by: Liam R. Howlett <[email protected]>
>Acked-by: Vlastimil Babka <[email protected]>
>Reviewed-by: David Hildenbrand <[email protected]>

Reviewed-by: Davidlohr Bueso <[email protected]>