[PATCH 3/3] memcg: fix LRU rotation of isolate_lru_pages with memcg

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

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

This patch tries to fix memcg's lru rotation logic to make memcg use
the same logic as global LRU does.

Now, at __isolate_lru_page() retruns -EBUSY, the page is rotated to
the tail of LRU in global LRU's isolate LRU pages. But in memcg,
it's not handled. This makes memcg do the same behavior as global LRU
and rotate LRU in the page is busy.

Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

---
Index: lumpy-reclaim-trial/mm/vmscan.c
===================================================================
--- lumpy-reclaim-trial.orig/mm/vmscan.c	2009-06-10 19:48:28.000000000 +0900
+++ lumpy-reclaim-trial/mm/vmscan.c	2009-06-10 20:06:55.000000000 +0900
@@ -844,7 +844,6 @@
 		 */
 		ClearPageLRU(page);
 		ret = 0;
-		mem_cgroup_del_lru(page);
 	}
 
 	return ret;
@@ -892,12 +891,14 @@
 		switch (__isolate_lru_page(page, mode, file)) {
 		case 0:
 			list_move(&page->lru, dst);
+			mem_cgroup_del_lru(page);
 			nr_taken++;
 			break;
 
 		case -EBUSY:
 			/* else it is being freed elsewhere */
 			list_move(&page->lru, src);
+			mem_cgroup_rotate_lru_list(page, page_lru(page));
 			continue;
 
 		default:
@@ -941,6 +942,7 @@
 				break;
 			if (__isolate_lru_page(cursor_page, mode, file) == 0) {
 				list_move(&cursor_page->lru, dst);
+				mem_cgroup_del_lru(page);
 				nr_taken++;
 				scan++;
 				break;
Index: lumpy-reclaim-trial/mm/memcontrol.c
===================================================================
--- lumpy-reclaim-trial.orig/mm/memcontrol.c	2009-06-10 17:30:23.000000000 +0900
+++ lumpy-reclaim-trial/mm/memcontrol.c	2009-06-10 20:05:21.000000000 +0900
@@ -649,6 +649,7 @@
 	int zid = zone_idx(z);
 	struct mem_cgroup_per_zone *mz;
 	int lru = LRU_FILE * !!file + !!active;
+	int ret;
 
 	BUG_ON(!mem_cont);
 	mz = mem_cgroup_zoneinfo(mem_cont, nid, zid);
@@ -666,9 +667,19 @@
 			continue;
 
 		scan++;
-		if (__isolate_lru_page(page, mode, file) == 0) {
+		ret = __isolate_lru_page(page, mode, file);
+		switch (ret) {
+		case 0:
 			list_move(&page->lru, dst);
+			mem_cgroup_del_lru(page);
 			nr_taken++;
+			break;
+		case -EBUSY:
+			/* we don't affect global LRU but rotate in our LRU */
+			mem_cgroup_rotate_lru_list(page, page_lru(page));
+			break;
+		default:
+			break;
 		}
 	}
 

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