[BUGFIX][PATCH] fix lumpy reclaim lru handiling at isolate_lru_pages v2

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

Sorry for noisy posts. I hope this should be the last trial.
Thank you for all helps.

-Kame
==
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

At lumpy reclaim, a page failed to be taken by __isolate_lru_page() can
be pushed back to "src" list by list_move(). But the page may not be from
"src" list. This pushes the page back to wrong LRU.
And list_move() itself is unnecessary because the page is
not on top of LRU. Then, leave it as it is if __isolate_lru_page() fails.

Changelog: v1->v2
 - removed buggy break.

Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
---
 mm/vmscan.c |   10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

Index: lumpy-reclaim-trial/mm/vmscan.c
===================================================================
--- lumpy-reclaim-trial.orig/mm/vmscan.c
+++ lumpy-reclaim-trial/mm/vmscan.c
@@ -936,18 +936,10 @@ static unsigned long isolate_lru_pages(u
 			/* Check that we have not crossed a zone boundary. */
 			if (unlikely(page_zone_id(cursor_page) != zone_id))
 				continue;
-			switch (__isolate_lru_page(cursor_page, mode, file)) {
-			case 0:
+			if (__isolate_lru_page(cursor_page, mode, file) == 0) {
 				list_move(&cursor_page->lru, dst);
 				nr_taken++;
 				scan++;
-				break;
-
-			case -EBUSY:
-				/* else it is being freed elsewhere */
-				list_move(&cursor_page->lru, src);
-			default:
-				break;	/* ! on LRU or wrong list */
 			}
 		}
 	}

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