[PATCH] memcg: fix mem_cgroup_isolate_lru_page to use the same rotate logic at busy path

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

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

This patch tries to fix memcg's lru rotation sanity...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.

Note: __isolate_lru_page() is not isolate_lru_page() and it's just used
in sc->isolate_pages() logic.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

---
 mm/memcontrol.c |   13 ++++++++++++-
 mm/vmscan.c     |    4 +++-
 2 files changed, 15 insertions(+), 2 deletions(-)

Index: mmotm-2.6.30-Jun4/mm/vmscan.c
===================================================================
--- mmotm-2.6.30-Jun4.orig/mm/vmscan.c
+++ mmotm-2.6.30-Jun4/mm/vmscan.c
@@ -842,7 +842,6 @@ int __isolate_lru_page(struct page *page
 		 */
 		ClearPageLRU(page);
 		ret = 0;
-		mem_cgroup_del_lru(page);
 	}
 
 	return ret;
@@ -890,12 +889,14 @@ static unsigned long isolate_lru_pages(u
 		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:
@@ -937,6 +938,7 @@ static unsigned long isolate_lru_pages(u
 			switch (__isolate_lru_page(cursor_page, mode, file)) {
 			case 0:
 				list_move(&cursor_page->lru, dst);
+				mem_cgroup_del_lru(page);
 				nr_taken++;
 				scan++;
 				break;
Index: mmotm-2.6.30-Jun4/mm/memcontrol.c
===================================================================
--- mmotm-2.6.30-Jun4.orig/mm/memcontrol.c
+++ mmotm-2.6.30-Jun4/mm/memcontrol.c
@@ -649,6 +649,7 @@ unsigned long mem_cgroup_isolate_pages(u
 	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 @@ unsigned long mem_cgroup_isolate_pages(u
 			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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