};
struct mem_cgroup_reclaim_iter {
- /* css_id of the last scanned hierarchy member */
- int position;
+ /*
+ * last scanned hierarchy member. Valid only if last_dead_count
+ * matches memcg->dead_count of the hierarchy root group.
+ */
+ struct mem_cgroup *last_visited;
+ unsigned long last_dead_count;
+
/* scan generation, increased every round-trip */
unsigned int generation;
};
struct mem_cgroup_stat_cpu nocpu_base;
spinlock_t pcp_counter_lock;
+ atomic_t dead_count;
#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_INET)
struct tcp_memcontrol tcp_mem;
#endif
struct mem_cgroup_reclaim_cookie *reclaim)
{
struct mem_cgroup *memcg = NULL;
- int id = 0;
+ struct mem_cgroup *last_visited = NULL;
+ unsigned long uninitialized_var(dead_count);
if (mem_cgroup_disabled())
return NULL;
root = root_mem_cgroup;
if (prev && !reclaim)
- id = css_id(&prev->css);
-
- if (prev && prev != root)
- css_put(&prev->css);
+ last_visited = prev;
if (!root->use_hierarchy && root != root_mem_cgroup) {
if (prev)
- return NULL;
+ goto out_css_put;
return root;
}
+ rcu_read_lock();
while (!memcg) {
struct mem_cgroup_reclaim_iter *uninitialized_var(iter);
- struct cgroup_subsys_state *css;
if (reclaim) {
int nid = zone_to_nid(reclaim->zone);
mz = mem_cgroup_zoneinfo(root, nid, zid);
iter = &mz->reclaim_iter[reclaim->priority];
- if (prev && reclaim->generation != iter->generation)
- return NULL;
- id = iter->position;
+ last_visited = iter->last_visited;
+ if (prev && reclaim->generation != iter->generation) {
+ iter->last_visited = NULL;
+ goto out_unlock;
+ }
+
+ /*
+ * If the dead_count mismatches, a destruction
+ * has happened or is happening concurrently.
+ * If the dead_count matches, a destruction
+ * might still happen concurrently, but since
+ * we checked under RCU, that destruction
+ * won't free the object until we release the
+ * RCU reader lock. Thus, the dead_count
+ * check verifies the pointer is still valid,
+ * css_tryget() verifies the cgroup pointed to
+ * is alive.
+ */
+ dead_count = atomic_read(&root->dead_count);
+ smp_rmb();
+ last_visited = iter->last_visited;
+ if (last_visited) {
+ if ((dead_count != iter->last_dead_count) ||
+ !css_tryget(&last_visited->css)) {
+ last_visited = NULL;
+ }
+ }
}
- rcu_read_lock();
- css = css_get_next(&mem_cgroup_subsys, id + 1, &root->css, &id);
- if (css) {
- if (css == &root->css || css_tryget(css))
- memcg = mem_cgroup_from_css(css);
- } else
- id = 0;
- rcu_read_unlock();
+ /*
+ * 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;
+ }
+ }
+ }
if (reclaim) {
- iter->position = id;
- if (!css)
+ if (last_visited)
+ css_put(&last_visited->css);
+
+ iter->last_visited = memcg;
+ smp_wmb();
+ iter->last_dead_count = dead_count;
+
+ if (!memcg)
iter->generation++;
else if (!prev && memcg)
reclaim->generation = iter->generation;
}
- if (prev && !css)
- return NULL;
+ if (prev && !memcg)
+ goto out_unlock;
}
+out_unlock:
+ rcu_read_unlock();
+out_css_put:
+ if (prev && prev != root)
+ css_put(&prev->css);
+
return memcg;
}
memcg_limited_groups_array_size = memcg_caches_array_size(num);
}
+static void kmem_cache_destroy_work_func(struct work_struct *w);
+
int memcg_update_cache_size(struct kmem_cache *s, int num_groups)
{
struct memcg_cache_params *cur_params = s->memcg_params;
return -ENOMEM;
}
+ INIT_WORK(&s->memcg_params->destroy,
+ kmem_cache_destroy_work_func);
s->memcg_params->is_root_cache = true;
/*
if (!s->memcg_params)
return -ENOMEM;
+ INIT_WORK(&s->memcg_params->destroy,
+ kmem_cache_destroy_work_func);
if (memcg) {
s->memcg_params->memcg = memcg;
s->memcg_params->root_cache = root_cache;
list_for_each_entry(params, &memcg->memcg_slab_caches, list) {
cachep = memcg_params_to_cache(params);
cachep->memcg_params->dead = true;
- INIT_WORK(&cachep->memcg_params->destroy,
- kmem_cache_destroy_work_func);
schedule_work(&cachep->memcg_params->destroy);
}
mutex_unlock(&memcg->slab_caches_mutex);
return error;
}
+/*
+ * Announce all parents that a group from their hierarchy is gone.
+ */
+static void mem_cgroup_invalidate_reclaim_iterators(struct mem_cgroup *memcg)
+{
+ struct mem_cgroup *parent = memcg;
+
+ while ((parent = parent_mem_cgroup(parent)))
+ atomic_inc(&parent->dead_count);
+
+ /*
+ * if the root memcg is not hierarchical we have to check it
+ * explicitely.
+ */
+ if (!root_mem_cgroup->use_hierarchy)
+ atomic_inc(&root_mem_cgroup->dead_count);
+}
+
static void mem_cgroup_css_offline(struct cgroup *cont)
{
struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+ mem_cgroup_invalidate_reclaim_iterators(memcg);
mem_cgroup_reparent_charges(memcg);
mem_cgroup_destroy_all_caches(memcg);
}
OSDN Git Service
