Re: [PATCH v4 08/66] mmap: Use the VMA iterator in count_vma_pages_range()
From: Vlastimil Babka <hidden>
Date: 2021-12-09 15:54:28
Also in:
lkml
On 12/1/21 15:29, Liam Howlett wrote:
From: "Matthew Wilcox (Oracle)" <willy@infradead.org> This simplifies the implementation and is faster than using the linked list.
You mean faster because more cache friendly? OTOH you do max(addr, vma->vm_start) which wasn't the case. I doubt it matters though and yeah it's much simpler...
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Vlastimil Babka <redacted> Btw, no signed-off-by Liam? I now also notice some other patches (e.g. patch 4) have From: and s-o-b by Liam followed by Matthew, despite it's Liam sending them. I guess that's less of an issue than the missing one. Anyway something for you to check and make consistent in the whole series, I won't point it out individually.
quoted hunk ↗ jump to hunk
--- mm/mmap.c | 24 +++++++----------------- 1 file changed, 7 insertions(+), 17 deletions(-)diff --git a/mm/mmap.c b/mm/mmap.c index 9fee6e6b276f..de78fc0ce809 100644 --- a/mm/mmap.c +++ b/mm/mmap.c@@ -669,29 +669,19 @@ 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 += (vm_end - vm_start) / PAGE_SIZE; } return nr_pages;