diff options
| -rw-r--r-- | mm/memcontrol.c | 33 |
1 files changed, 30 insertions, 3 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 4e705ed74b81..ff648969e402 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -250,6 +250,9 @@ struct mem_cgroup { /* vmpressure notifications */ struct vmpressure vmpressure; + /* css_online() has been completed */ + int initialized; + /* * the counter to account for mem+swap usage. */ @@ -1089,9 +1092,23 @@ skip_node: * skipping css reference should be safe. */ if (next_css) { - if ((next_css == &root->css) || - ((next_css->flags & CSS_ONLINE) && css_tryget(next_css))) - return mem_cgroup_from_css(next_css); + struct mem_cgroup *memcg = mem_cgroup_from_css(next_css); + + if (next_css == &root->css) + return memcg; + + if (css_tryget(next_css)) { + if (memcg->initialized) { + /* + * Make sure the memcg is initialized: + * mem_cgroup_css_online() orders the the + * initialization against setting the flag. + */ + smp_rmb(); + return memcg; + } + css_put(next_css); + } prev_css = next_css; goto skip_node; @@ -6331,6 +6348,16 @@ mem_cgroup_css_online(struct cgroup_subsys_state *css) error = memcg_init_kmem(memcg, &mem_cgroup_subsys); mutex_unlock(&memcg_create_mutex); + + if (!error) { + /* + * Make sure the memcg is initialized: mem_cgroup_iter() + * orders reading memcg->initialized against its callers + * reading the memcg members. + */ + smp_wmb(); + memcg->initialized = 1; + } return error; } |