mem_cgroup_get_nr_swap_pages
extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
mem_cgroup_get_nr_swap_pages(memcg) < MIN_LRU_BATCH)
if (mem_cgroup_get_nr_swap_pages(memcg) > 0)
if (mem_cgroup_get_nr_swap_pages(eviction_memcg) > 0) {