On Thu, Aug 28, 2025 at 12:01:22AM +0200, David Hildenbrand wrote:
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
This looks correct to me, so notwithtsanding suggestion below, LGTM and:
Reviewed-by: Lorenzo Stoakes lorenzo.stoakes@oracle.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++;
This is really nice, but I wonder if (while we're here) we can't be even more clear as to what's going on here, e.g.:
static int record_subpages(struct page *page, unsigned long sz, unsigned long addr, unsigned long end, struct page **pages) { size_t offset_in_folio = (addr & (sz - 1)) >> PAGE_SHIFT; struct page *subpage = page + offset_in_folio;
for (; addr != end; addr += PAGE_SIZE) *pages++ = subpage++;
return nr; }
Or some variant of that with the masking stuff self-documented.
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
Cheers, Lorenzo