On 2020/5/15 12:14, Matthew Wilcox wrote:

On Thu, May 07, 2020 at 03:50:56PM +0800, Zhen Lei wrote:

quoted

+++ b/mm/page_io.c

@@ -38,7 +38,7 @@ static struct bio *get_swap_bio(gfp_t gfp_flags,
 
 		bio->bi_iter.bi_sector = map_swap_page(page, &bdev);
 		bio_set_dev(bio, bdev);
-		bio->bi_iter.bi_sector <<= PAGE_SHIFT - 9;
+		bio->bi_iter.bi_sector *= PAGE_SECTORS;
 		bio->bi_end_io = end_io;

This just doesn't look right.  Why is map_swap_page() returning a sector_t
which isn't actually a sector_t?

I try to understand map_swap_page(). Here maybe a bug. Otherwise, it would be
better to add a temporary variable to cache the return value of map_swap_page(page, &bdev).

.