+static int shrinker_nr_max;
+
+/* The shrinker_info is expanded in a batch of BITS_PER_LONG */
+static inline int shrinker_map_size(int nr_items)
+{
+ return (DIV_ROUND_UP(nr_items, BITS_PER_LONG) * sizeof(unsigned long));
+}
+
+static inline int shrinker_defer_size(int nr_items)
+{
+ return (round_up(nr_items, BITS_PER_LONG) * sizeof(atomic_long_t));
+}
+
+static struct shrinker_info *shrinker_info_protected(struct mem_cgroup *memcg,
+ int nid)
+{
+ return rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_info,
+ lockdep_is_held(&shrinker_rwsem));
+}
+
+static int expand_one_shrinker_info(struct mem_cgroup *memcg,
+ int map_size, int defer_size,
+ int old_map_size, int old_defer_size)
+{
+ struct shrinker_info *new, *old;
+ struct mem_cgroup_per_node *pn;
+ int nid;
+ int size = map_size + defer_size;
+
+ for_each_node(nid) {
+ pn = memcg->nodeinfo[nid];
+ old = shrinker_info_protected(memcg, nid);
+ /* Not yet online memcg */
+ if (!old)
+ return 0;
+
+ new = kvmalloc_node(sizeof(*new) + size, GFP_KERNEL, nid);
+ if (!new)
+ return -ENOMEM;
+
+ new->nr_deferred = (atomic_long_t *)(new + 1);
+ new->map = (void *)new->nr_deferred + defer_size;
+
+ /* map: set all old bits, clear all new bits */
+ memset(new->map, (int)0xff, old_map_size);
+ memset((void *)new->map + old_map_size, 0, map_size - old_map_size);
+ /* nr_deferred: copy old values, clear all new values */
+ memcpy(new->nr_deferred, old->nr_deferred, old_defer_size);
+ memset((void *)new->nr_deferred + old_defer_size, 0,
+ defer_size - old_defer_size);
+
+ rcu_assign_pointer(pn->shrinker_info, new);
+ kvfree_rcu(old, rcu);
+ }
+
+ return 0;
+}
+
+void free_shrinker_info(struct mem_cgroup *memcg)
+{
+ struct mem_cgroup_per_node *pn;
+ struct shrinker_info *info;
+ int nid;
+
+ for_each_node(nid) {
+ pn = memcg->nodeinfo[nid];
+ info = rcu_dereference_protected(pn->shrinker_info, true);
+ kvfree(info);
+ rcu_assign_pointer(pn->shrinker_info, NULL);
+ }
+}
+
+int alloc_shrinker_info(struct mem_cgroup *memcg)
+{
+ struct shrinker_info *info;
+ int nid, size, ret = 0;
+ int map_size, defer_size = 0;
+
+ down_write(&shrinker_rwsem);
+ map_size = shrinker_map_size(shrinker_nr_max);
+ defer_size = shrinker_defer_size(shrinker_nr_max);
+ size = map_size + defer_size;
+ for_each_node(nid) {
+ info = kvzalloc_node(sizeof(*info) + size, GFP_KERNEL, nid);
+ if (!info) {
+ free_shrinker_info(memcg);
+ ret = -ENOMEM;
+ break;
+ }
+ info->nr_deferred = (atomic_long_t *)(info + 1);
+ info->map = (void *)info->nr_deferred + defer_size;
+ rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_info, info);
+ }
+ up_write(&shrinker_rwsem);
+
+ return ret;
+}
+
+static inline bool need_expand(int nr_max)
+{
+ return round_up(nr_max, BITS_PER_LONG) >
+ round_up(shrinker_nr_max, BITS_PER_LONG);
+}
+
+static int expand_shrinker_info(int new_id)
+{
+ int ret = 0;
+ int new_nr_max = new_id + 1;
+ int map_size, defer_size = 0;
+ int old_map_size, old_defer_size = 0;
+ struct mem_cgroup *memcg;
+
+ if (!need_expand(new_nr_max))
+ goto out;
+
+ if (!root_mem_cgroup)
+ goto out;
+
+ lockdep_assert_held(&shrinker_rwsem);
+
+ map_size = shrinker_map_size(new_nr_max);
+ defer_size = shrinker_defer_size(new_nr_max);
+ old_map_size = shrinker_map_size(shrinker_nr_max);
+ old_defer_size = shrinker_defer_size(shrinker_nr_max);
+
+ memcg = mem_cgroup_iter(NULL, NULL, NULL);
+ do {
+ ret = expand_one_shrinker_info(memcg, map_size, defer_size,
+ old_map_size, old_defer_size);
+ if (ret) {
+ mem_cgroup_iter_break(NULL, memcg);
+ goto out;
+ }
+ } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL);
+out:
+ if (!ret)
+ shrinker_nr_max = new_nr_max;
+
+ return ret;
+}
+
+void set_shrinker_bit(struct mem_cgroup *memcg, int nid, int shrinker_id)
+{
+ if (shrinker_id >= 0 && memcg && !mem_cgroup_is_root(memcg)) {
+ struct shrinker_info *info;
+
+ rcu_read_lock();
+ info = rcu_dereference(memcg->nodeinfo[nid]->shrinker_info);
+ /* Pairs with smp mb in shrink_slab() */
+ smp_mb__before_atomic();
+ set_bit(shrinker_id, info->map);
+ rcu_read_unlock();
+ }
+}