[PATCH] fix

[Minchan Kim]

Not-Yet-Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
---
 mm/page_io.c | 54 ----------------------------------------------------
 1 file changed, 54 deletions(-)

diff --git a/mm/page_io.c b/mm/page_io.c
index 0bf8e40f4e57..d3eea0a3f1af 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -51,54 +51,6 @@ void end_swap_bio_write(struct bio *bio)
 	bio_put(bio);
 }
 
-static void swap_slot_free_notify(struct page *page)
-{
-	struct swap_info_struct *sis;
-	struct gendisk *disk;
-	swp_entry_t entry;
-
-	/*
-	 * There is no guarantee that the page is in swap cache - the software
-	 * suspend code (at least) uses end_swap_bio_read() against a non-
-	 * swapcache page.  So we must check PG_swapcache before proceeding with
-	 * this optimization.
-	 */
-	if (unlikely(!PageSwapCache(page)))
-		return;
-
-	sis = page_swap_info(page);
-	if (data_race(!(sis->flags & SWP_BLKDEV)))
-		return;
-
-	/*
-	 * The swap subsystem performs lazy swap slot freeing,
-	 * expecting that the page will be swapped out again.
-	 * So we can avoid an unnecessary write if the page
-	 * isn't redirtied.
-	 * This is good for real swap storage because we can
-	 * reduce unnecessary I/O and enhance wear-leveling
-	 * if an SSD is used as the as swap device.
-	 * But if in-memory swap device (eg zram) is used,
-	 * this causes a duplicated copy between uncompressed
-	 * data in VM-owned memory and compressed data in
-	 * zram-owned memory.  So let's free zram-owned memory
-	 * and make the VM-owned decompressed page *dirty*,
-	 * so the page should be swapped out somewhere again if
-	 * we again wish to reclaim it.
-	 */
-	disk = sis->bdev->bd_disk;
-	entry.val = page_private(page);
-	if (disk->fops->swap_slot_free_notify && __swap_count(entry) == 1) {
-		unsigned long offset;
-
-		offset = swp_offset(entry);
-
-		SetPageDirty(page);
-		disk->fops->swap_slot_free_notify(sis->bdev,
-				offset);
-	}
-}
-
 static void end_swap_bio_read(struct bio *bio)
 {
 	struct page *page = bio_first_page_all(bio);
@@ -114,7 +66,6 @@ static void end_swap_bio_read(struct bio *bio)
 	}
 
 	SetPageUptodate(page);
-	swap_slot_free_notify(page);
 out:
 	unlock_page(page);
 	WRITE_ONCE(bio->bi_private, NULL);
@@ -392,11 +343,6 @@ int swap_readpage(struct page *page, bool synchronous)
 	if (sis->flags & SWP_SYNCHRONOUS_IO) {
 		ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
 		if (!ret) {
-			if (trylock_page(page)) {
-				swap_slot_free_notify(page);
-				unlock_page(page);
-			}
-
 			count_vm_event(PSWPIN);
 			goto out;
 		}
-- 
2.35.1.723.g4982287a31-goog