[PATCH RFC 17/35] mm/gup: drop nth_page() usage within folio when recording subpages

David Hildenbrand
2025-08-21T21:33:41Z

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

Signed-off-by: David Hildenbrand <david@redhat.com>
---
mm/gup.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index b2a78f0291273..f017ff6d7d61a 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -491,9 +491,9 @@ static int record_subpages(struct page *page, unsigned long sz,
struct page *start_page;
int nr;

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

return nr;
}
@@ -1512,7 +1512,7 @@ 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