mm/cgroup: avoid panic when init with low memory

[linux-block.git] / mm / memcontrol.c

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c52ec893e241cf6b52764797f6aea5ed56219e23..76f513cc1b0ee7769e74a3d1a48d5d37ce67da36 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -466,6 +466,8 @@ static void mem_cgroup_update_tree(struct mem_cgroup *memcg, struct page *page)
        struct mem_cgroup_tree_per_node *mctz;
 
        mctz = soft_limit_tree_from_page(page);
+       if (!mctz)
+               return;
        /*
         * Necessary to update all ancestors when hierarchy is used.
         * because their event counter is not touched.
@@ -503,7 +505,8 @@ static void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg)
        for_each_node(nid) {
                mz = mem_cgroup_nodeinfo(memcg, nid);
                mctz = soft_limit_tree_node(nid);
-               mem_cgroup_remove_exceeded(mz, mctz);
+               if (mctz)
+                       mem_cgroup_remove_exceeded(mz, mctz);
        }
 }
 
@@ -2558,7 +2561,7 @@ unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
         * is empty. Do it lockless to prevent lock bouncing. Races
         * are acceptable as soft limit is best effort anyway.
         */
-       if (RB_EMPTY_ROOT(&mctz->rb_root))
+       if (!mctz || RB_EMPTY_ROOT(&mctz->rb_root))
                return 0;
 
        /*