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SubjectRe: [PATCH v10 10/69] mmap: use the VMA iterator in count_vma_pages_range()
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On 21.06.22 22:46, Liam Howlett wrote:
> From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
>
> This simplifies the implementation and is faster than using the linked
> list.
>
> Link: https://lkml.kernel.org/r/20220504010716.661115-12-Liam.Howlett@oracle.com
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
> Acked-by: Vlastimil Babka <vbabka@suse.cz>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: David Howells <dhowells@redhat.com>
> Cc: SeongJae Park <sj@kernel.org>
> Cc: Will Deacon <will@kernel.org>
> Cc: Davidlohr Bueso <dave@stgolabs.net>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
> mm/mmap.c | 24 +++++++-----------------
> 1 file changed, 7 insertions(+), 17 deletions(-)
>
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 6be7833c781b..d7e6baa2f40f 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -675,29 +675,19 @@ 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);

I thought using max_t and min_t was the latest advisory. I might be
wrong and simply kept doing it that way ;)

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

PHYS_PFN(vm_end - vm_start)

> }
>
> return nr_pages;

Reviewed-by: David Hildenbrand <david@redhat.com>

--
Thanks,

David / dhildenb

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