[PATCH 05/11] memcg: add null check to page_cgroup_zoneinfo()

KOSAKI Motohiro
2008-12-01T12:15:20Z

if CONFIG_CGROUP_MEM_RES_CTLR_SWAP=y, page_cgroup::mem_cgroup can be NULL.
Therefore null checking is better.

latter patch use this function.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
---
mm/memcontrol.c | 3 +++
1 file changed, 3 insertions(+)

Index: b/mm/memcontrol.c
===================================================================
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -231,6 +231,9 @@ page_cgroup_zoneinfo(struct page_cgroup
int nid = page_cgroup_nid(pc);
int zid = page_cgroup_zid(pc);

+ if (!mem)
+ return NULL;
+
return mem_cgroup_zoneinfo(mem, nid, zid);
}