diff options
| -rw-r--r-- | mm/memcontrol.c | 79 |
1 files changed, 46 insertions, 33 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 614d0d9c0deb..2bdac3ececd0 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1073,6 +1073,51 @@ struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm) return memcg; } +/* + * Returns a next (in a pre-order walk) alive memcg (with elevated css + * ref. count) or NULL if the whole root's subtree has been visited. + * + * helper function to be used by mem_cgroup_iter + */ +static struct mem_cgroup *__mem_cgroup_iter_next(struct mem_cgroup *root, + struct mem_cgroup *last_visited) +{ + struct cgroup *prev_cgroup, *next_cgroup; + + /* + * Root is not visited by cgroup iterators so it needs an + * explicit visit. + */ + if (!last_visited) + return root; + + prev_cgroup = (last_visited == root) ? NULL + : last_visited->css.cgroup; +skip_node: + next_cgroup = cgroup_next_descendant_pre( + prev_cgroup, root->css.cgroup); + + /* + * Even if we found a group we have to make sure it is + * alive. css && !memcg means that the groups should be + * skipped and we should continue the tree walk. + * last_visited css is safe to use because it is + * protected by css_get and the tree walk is rcu safe. + */ + if (next_cgroup) { + struct mem_cgroup *mem = mem_cgroup_from_cont( + next_cgroup); + if (css_tryget(&mem->css)) + return mem; + else { + prev_cgroup = next_cgroup; + goto skip_node; + } + } + + return NULL; +} + /** * mem_cgroup_iter - iterate over memory cgroup hierarchy * @root: hierarchy root @@ -1153,39 +1198,7 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root, } } - /* - * Root is not visited by cgroup iterators so it needs an - * explicit visit. - */ - if (!last_visited) { - memcg = root; - } else { - struct cgroup *prev_cgroup, *next_cgroup; - - prev_cgroup = (last_visited == root) ? NULL - : last_visited->css.cgroup; -skip_node: - next_cgroup = cgroup_next_descendant_pre( - prev_cgroup, root->css.cgroup); - - /* - * Even if we found a group we have to make sure it is - * alive. css && !memcg means that the groups should be - * skipped and we should continue the tree walk. - * last_visited css is safe to use because it is - * protected by css_get and the tree walk is rcu safe. - */ - if (next_cgroup) { - struct mem_cgroup *mem = mem_cgroup_from_cont( - next_cgroup); - if (css_tryget(&mem->css)) - memcg = mem; - else { - prev_cgroup = next_cgroup; - goto skip_node; - } - } - } + memcg = __mem_cgroup_iter_next(root, last_visited); if (reclaim) { if (last_visited) |