mem_cgroup_get_nr_swap_pages  662 include/linux/swap.h extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
mem_cgroup_get_nr_swap_pages 2320 mm/vmscan.c    	if (!sc->may_swap || mem_cgroup_get_nr_swap_pages(memcg) <= 0) {