[PATCH for v5.8 3/3] mm/memory: fix IO cost for anonymous page

[js1304]

From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>

With synchronous IO swap device, swap-in is directly handled in fault
code. Since IO cost notation isn't added there, with synchronous IO swap
device, LRU balancing could be wrongly biased. Fix it to count it
in fault code.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
---
 mm/memory.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/mm/memory.c b/mm/memory.c
index bc6a471..3359057 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3143,6 +3143,14 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 				if (err)
 					goto out_page;
 
+				/*
+				 * XXX: Move to lru_cache_add() when it
+				 * supports new vs putback
+				 */
+				spin_lock_irq(&page_pgdat(page)->lru_lock);
+				lru_note_cost_page(page);
+				spin_unlock_irq(&page_pgdat(page)->lru_lock);
+
 				lru_cache_add(page);
 				swap_readpage(page, true);
 			}
-- 
2.7.4