[PATCH v2 18/37] mm/gup: drop nth_page() usage within folio when recording subpages

David Hildenbrand
2025-09-01T15:31:52Z

nth_page() is no longer required when iterating over pages within a
single folio, so let's just drop it when recording subpages.

Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
mm/gup.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 8157197a19f77..c10cd969c1a3b 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -488,12 +488,11 @@ static int record_subpages(struct page *page, unsigned long sz,
unsigned long addr, unsigned long end,
struct page **pages)
{
- struct page *start_page;
int nr;

- start_page = nth_page(page, (addr & (sz - 1)) >> PAGE_SHIFT);
+ page += (addr & (sz - 1)) >> PAGE_SHIFT;
for (nr = 0; addr != end; nr++, addr += PAGE_SIZE)
- pages[nr] = nth_page(start_page, nr);
+ pages[nr] = page++;

return nr;
}
@@ -1512,7 +1511,7 @@ static long __get_user_pages(struct mm_struct *mm,
}

for (j = 0; j < page_increm; j++) {
- subpage = nth_page(page, j);
+ subpage = page + j;
pages[i + j] = subpage;
flush_anon_page(vma, subpage, start + j * PAGE_SIZE);
flush_dcache_page(subpage);
--
2.50.1