[PATCH v1 18/36] mm/gup: drop nth_page() usage within folio when recording subpages

David Hildenbrand david at redhat.com
Wed Aug 27 15:01:22 PDT 2025


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 at redhat.com>
---
 mm/gup.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index b2a78f0291273..89ca0813791ab 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




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