mm/zswap: avoid unnecessary page scanning

Add SetPageReclaim() before __swap_writepage() so that page can be moved
to the tail of the inactive list, which can avoid unnecessary page
scanning as this page was reclaimed by swap subsystem before.
Signed-off-by: Weijie Yang <weijie.yang@samsung.com>
Reviewed-by: Bob Liu <bob.liu@oracle.com>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/zswap.c

@@ -556,6 +556,9 @@ static int zswap_writeback_entry(struct zbud_pool *pool, unsigned long handle)
 		SetPageUptodate(page);
 	}
 
+	/* move it to the tail of the inactive list after end_writeback */
+	SetPageReclaim(page);
+
 	/* start writeback */
 	__swap_writepage(page, &wbc, end_swap_bio_write);
 	page_cache_release(page);