127 static int __try_to_reclaim_swap(struct swap_info_struct *si,  in __try_to_reclaim_swap()  argument
130 	swp_entry_t entry = swp_entry(si->type, offset);  in __try_to_reclaim_swap()
171 static int discard_swap(struct swap_info_struct *si)  in discard_swap()  argument
179 	se = first_se(si);  in discard_swap()
183 		err = blkdev_issue_discard(si->bdev, start_block,  in discard_swap()
194 		err = blkdev_issue_discard(si->bdev, start_block,  in discard_swap()
228 static void discard_swap_cluster(struct swap_info_struct *si,  in discard_swap_cluster()  argument
231 	struct swap_extent *se = offset_to_swap_extent(si, start_page);  in discard_swap_cluster()
245 		if (blkdev_issue_discard(si->bdev, start_block,  in discard_swap_cluster()
338 static inline struct swap_cluster_info *lock_cluster(struct swap_info_struct *si,  in lock_cluster()  argument
343 	ci = si->cluster_info;  in lock_cluster()
362 		struct swap_info_struct *si, unsigned long offset)  in lock_cluster_or_swap_info()  argument
367 	ci = lock_cluster(si, offset);  in lock_cluster_or_swap_info()
370 		spin_lock(&si->lock);  in lock_cluster_or_swap_info()
375 static inline void unlock_cluster_or_swap_info(struct swap_info_struct *si,  in unlock_cluster_or_swap_info()  argument
381 		spin_unlock(&si->lock);  in unlock_cluster_or_swap_info()
440 static void swap_cluster_schedule_discard(struct swap_info_struct *si,  in swap_cluster_schedule_discard()  argument
449 	memset(si->swap_map + idx * SWAPFILE_CLUSTER,  in swap_cluster_schedule_discard()
452 	cluster_list_add_tail(&si->discard_clusters, si->cluster_info, idx);  in swap_cluster_schedule_discard()
454 	schedule_work(&si->discard_work);  in swap_cluster_schedule_discard()
457 static void __free_cluster(struct swap_info_struct *si, unsigned long idx)  in __free_cluster()  argument
459 	struct swap_cluster_info *ci = si->cluster_info;  in __free_cluster()
462 	cluster_list_add_tail(&si->free_clusters, ci, idx);  in __free_cluster()
469 static void swap_do_scheduled_discard(struct swap_info_struct *si)  in swap_do_scheduled_discard()  argument
474 	info = si->cluster_info;  in swap_do_scheduled_discard()
476 	while (!cluster_list_empty(&si->discard_clusters)) {  in swap_do_scheduled_discard()
477 		idx = cluster_list_del_first(&si->discard_clusters, info);  in swap_do_scheduled_discard()
478 		spin_unlock(&si->lock);  in swap_do_scheduled_discard()
480 		discard_swap_cluster(si, idx * SWAPFILE_CLUSTER,  in swap_do_scheduled_discard()
483 		spin_lock(&si->lock);  in swap_do_scheduled_discard()
484 		ci = lock_cluster(si, idx * SWAPFILE_CLUSTER);  in swap_do_scheduled_discard()
485 		__free_cluster(si, idx);  in swap_do_scheduled_discard()
486 		memset(si->swap_map + idx * SWAPFILE_CLUSTER,  in swap_do_scheduled_discard()
494 	struct swap_info_struct *si;  in swap_discard_work()  local
496 	si = container_of(work, struct swap_info_struct, discard_work);  in swap_discard_work()
498 	spin_lock(&si->lock);  in swap_discard_work()
499 	swap_do_scheduled_discard(si);  in swap_discard_work()
500 	spin_unlock(&si->lock);  in swap_discard_work()
503 static void alloc_cluster(struct swap_info_struct *si, unsigned long idx)  in alloc_cluster()  argument
505 	struct swap_cluster_info *ci = si->cluster_info;  in alloc_cluster()
507 	VM_BUG_ON(cluster_list_first(&si->free_clusters) != idx);  in alloc_cluster()
508 	cluster_list_del_first(&si->free_clusters, ci);  in alloc_cluster()
512 static void free_cluster(struct swap_info_struct *si, unsigned long idx)  in free_cluster()  argument
514 	struct swap_cluster_info *ci = si->cluster_info + idx;  in free_cluster()
522 	if ((si->flags & (SWP_WRITEOK | SWP_PAGE_DISCARD)) ==  in free_cluster()
524 		swap_cluster_schedule_discard(si, idx);  in free_cluster()
528 	__free_cluster(si, idx);  in free_cluster()
576 scan_swap_map_ssd_cluster_conflict(struct swap_info_struct *si,  in scan_swap_map_ssd_cluster_conflict()  argument
583 	conflict = !cluster_list_empty(&si->free_clusters) &&  in scan_swap_map_ssd_cluster_conflict()
584 		offset != cluster_list_first(&si->free_clusters) &&  in scan_swap_map_ssd_cluster_conflict()
585 		cluster_is_free(&si->cluster_info[offset]);  in scan_swap_map_ssd_cluster_conflict()
590 	percpu_cluster = this_cpu_ptr(si->percpu_cluster);  in scan_swap_map_ssd_cluster_conflict()
599 static bool scan_swap_map_try_ssd_cluster(struct swap_info_struct *si,  in scan_swap_map_try_ssd_cluster()  argument
608 	cluster = this_cpu_ptr(si->percpu_cluster);  in scan_swap_map_try_ssd_cluster()
610 		if (!cluster_list_empty(&si->free_clusters)) {  in scan_swap_map_try_ssd_cluster()
611 			cluster->index = si->free_clusters.head;  in scan_swap_map_try_ssd_cluster()
614 		} else if (!cluster_list_empty(&si->discard_clusters)) {  in scan_swap_map_try_ssd_cluster()
619 			swap_do_scheduled_discard(si);  in scan_swap_map_try_ssd_cluster()
620 			*scan_base = *offset = si->cluster_next;  in scan_swap_map_try_ssd_cluster()
633 	max = min_t(unsigned long, si->max,  in scan_swap_map_try_ssd_cluster()
639 	ci = lock_cluster(si, tmp);  in scan_swap_map_try_ssd_cluster()
641 		if (!si->swap_map[tmp]) {  in scan_swap_map_try_ssd_cluster()
673 static void swap_range_alloc(struct swap_info_struct *si, unsigned long offset,  in swap_range_alloc()  argument
678 	if (offset == si->lowest_bit)  in swap_range_alloc()
679 		si->lowest_bit += nr_entries;  in swap_range_alloc()
680 	if (end == si->highest_bit)  in swap_range_alloc()
681 		si->highest_bit -= nr_entries;  in swap_range_alloc()
682 	si->inuse_pages += nr_entries;  in swap_range_alloc()
683 	if (si->inuse_pages == si->pages) {  in swap_range_alloc()
684 		si->lowest_bit = si->max;  in swap_range_alloc()
685 		si->highest_bit = 0;  in swap_range_alloc()
686 		del_from_avail_list(si);  in swap_range_alloc()
702 static void swap_range_free(struct swap_info_struct *si, unsigned long offset,  in swap_range_free()  argument
708 	if (offset < si->lowest_bit)  in swap_range_free()
709 		si->lowest_bit = offset;  in swap_range_free()
710 	if (end > si->highest_bit) {  in swap_range_free()
711 		bool was_full = !si->highest_bit;  in swap_range_free()
713 		si->highest_bit = end;  in swap_range_free()
714 		if (was_full && (si->flags & SWP_WRITEOK))  in swap_range_free()
715 			add_to_avail_list(si);  in swap_range_free()
718 	si->inuse_pages -= nr_entries;  in swap_range_free()
719 	if (si->flags & SWP_BLKDEV)  in swap_range_free()
721 			si->bdev->bd_disk->fops->swap_slot_free_notify;  in swap_range_free()
725 		frontswap_invalidate_page(si->type, offset);  in swap_range_free()
727 			swap_slot_free_notify(si->bdev, offset);  in swap_range_free()
732 static int scan_swap_map_slots(struct swap_info_struct *si,  in scan_swap_map_slots()  argument
757 	si->flags += SWP_SCANNING;  in scan_swap_map_slots()
758 	scan_base = offset = si->cluster_next;  in scan_swap_map_slots()
761 	if (si->cluster_info) {  in scan_swap_map_slots()
762 		if (scan_swap_map_try_ssd_cluster(si, &offset, &scan_base))  in scan_swap_map_slots()
768 	if (unlikely(!si->cluster_nr--)) {  in scan_swap_map_slots()
769 		if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER) {  in scan_swap_map_slots()
770 			si->cluster_nr = SWAPFILE_CLUSTER - 1;  in scan_swap_map_slots()
774 		spin_unlock(&si->lock);  in scan_swap_map_slots()
782 		scan_base = offset = si->lowest_bit;  in scan_swap_map_slots()
786 		for (; last_in_cluster <= si->highest_bit; offset++) {  in scan_swap_map_slots()
787 			if (si->swap_map[offset])  in scan_swap_map_slots()
790 				spin_lock(&si->lock);  in scan_swap_map_slots()
792 				si->cluster_next = offset;  in scan_swap_map_slots()
793 				si->cluster_nr = SWAPFILE_CLUSTER - 1;  in scan_swap_map_slots()
803 		spin_lock(&si->lock);  in scan_swap_map_slots()
804 		si->cluster_nr = SWAPFILE_CLUSTER - 1;  in scan_swap_map_slots()
808 	if (si->cluster_info) {  in scan_swap_map_slots()
809 		while (scan_swap_map_ssd_cluster_conflict(si, offset)) {  in scan_swap_map_slots()
813 			if (!scan_swap_map_try_ssd_cluster(si, &offset,  in scan_swap_map_slots()
818 	if (!(si->flags & SWP_WRITEOK))  in scan_swap_map_slots()
820 	if (!si->highest_bit)  in scan_swap_map_slots()
822 	if (offset > si->highest_bit)  in scan_swap_map_slots()
823 		scan_base = offset = si->lowest_bit;  in scan_swap_map_slots()
825 	ci = lock_cluster(si, offset);  in scan_swap_map_slots()
827 	if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) {  in scan_swap_map_slots()
830 		spin_unlock(&si->lock);  in scan_swap_map_slots()
831 		swap_was_freed = __try_to_reclaim_swap(si, offset, TTRS_ANYWAY);  in scan_swap_map_slots()
832 		spin_lock(&si->lock);  in scan_swap_map_slots()
839 	if (si->swap_map[offset]) {  in scan_swap_map_slots()
846 	si->swap_map[offset] = usage;  in scan_swap_map_slots()
847 	inc_cluster_info_page(si, si->cluster_info, offset);  in scan_swap_map_slots()
850 	swap_range_alloc(si, offset, 1);  in scan_swap_map_slots()
851 	si->cluster_next = offset + 1;  in scan_swap_map_slots()
852 	slots[n_ret++] = swp_entry(si->type, offset);  in scan_swap_map_slots()
855 	if ((n_ret == nr) || (offset >= si->highest_bit))  in scan_swap_map_slots()
864 		spin_unlock(&si->lock);  in scan_swap_map_slots()
866 		spin_lock(&si->lock);  in scan_swap_map_slots()
871 	if (si->cluster_info) {  in scan_swap_map_slots()
872 		if (scan_swap_map_try_ssd_cluster(si, &offset, &scan_base))  in scan_swap_map_slots()
881 	if (si->cluster_nr && !si->swap_map[offset]) {  in scan_swap_map_slots()
882 		--si->cluster_nr;  in scan_swap_map_slots()
887 	si->flags -= SWP_SCANNING;  in scan_swap_map_slots()
891 	spin_unlock(&si->lock);  in scan_swap_map_slots()
892 	while (++offset <= si->highest_bit) {  in scan_swap_map_slots()
893 		if (!si->swap_map[offset]) {  in scan_swap_map_slots()
894 			spin_lock(&si->lock);  in scan_swap_map_slots()
897 		if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) {  in scan_swap_map_slots()
898 			spin_lock(&si->lock);  in scan_swap_map_slots()
906 	offset = si->lowest_bit;  in scan_swap_map_slots()
908 		if (!si->swap_map[offset]) {  in scan_swap_map_slots()
909 			spin_lock(&si->lock);  in scan_swap_map_slots()
912 		if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) {  in scan_swap_map_slots()
913 			spin_lock(&si->lock);  in scan_swap_map_slots()
922 	spin_lock(&si->lock);  in scan_swap_map_slots()
925 	si->flags -= SWP_SCANNING;  in scan_swap_map_slots()
929 static int swap_alloc_cluster(struct swap_info_struct *si, swp_entry_t *slot)  in swap_alloc_cluster()  argument
945 	if (cluster_list_empty(&si->free_clusters))  in swap_alloc_cluster()
948 	idx = cluster_list_first(&si->free_clusters);  in swap_alloc_cluster()
950 	ci = lock_cluster(si, offset);  in swap_alloc_cluster()
951 	alloc_cluster(si, idx);  in swap_alloc_cluster()
954 	map = si->swap_map + offset;  in swap_alloc_cluster()
958 	swap_range_alloc(si, offset, SWAPFILE_CLUSTER);  in swap_alloc_cluster()
959 	*slot = swp_entry(si->type, offset);  in swap_alloc_cluster()
964 static void swap_free_cluster(struct swap_info_struct *si, unsigned long idx)  in swap_free_cluster()  argument
969 	ci = lock_cluster(si, offset);  in swap_free_cluster()
970 	memset(si->swap_map + offset, 0, SWAPFILE_CLUSTER);  in swap_free_cluster()
972 	free_cluster(si, idx);  in swap_free_cluster()
974 	swap_range_free(si, offset, SWAPFILE_CLUSTER);  in swap_free_cluster()
977 static unsigned long scan_swap_map(struct swap_info_struct *si,  in scan_swap_map()  argument
983 	n_ret = scan_swap_map_slots(si, usage, 1, &entry);  in scan_swap_map()
995 	struct swap_info_struct *si, *next;  in get_swap_pages()  local
1019 	plist_for_each_entry_safe(si, next, &swap_avail_heads[node], avail_lists[node]) {  in get_swap_pages()
1021 		plist_requeue(&si->avail_lists[node], &swap_avail_heads[node]);  in get_swap_pages()
1023 		spin_lock(&si->lock);  in get_swap_pages()
1024 		if (!si->highest_bit || !(si->flags & SWP_WRITEOK)) {  in get_swap_pages()
1026 			if (plist_node_empty(&si->avail_lists[node])) {  in get_swap_pages()
1027 				spin_unlock(&si->lock);  in get_swap_pages()
1030 			WARN(!si->highest_bit,  in get_swap_pages()
1032 			     si->type);  in get_swap_pages()
1033 			WARN(!(si->flags & SWP_WRITEOK),  in get_swap_pages()
1035 			     si->type);  in get_swap_pages()
1036 			__del_from_avail_list(si);  in get_swap_pages()
1037 			spin_unlock(&si->lock);  in get_swap_pages()
1041 			if (!(si->flags & SWP_FS))  in get_swap_pages()
1042 				n_ret = swap_alloc_cluster(si, swp_entries);  in get_swap_pages()
1044 			n_ret = scan_swap_map_slots(si, SWAP_HAS_CACHE,  in get_swap_pages()
1046 		spin_unlock(&si->lock);  in get_swap_pages()
1050 			si->type);  in get_swap_pages()
1082 	struct swap_info_struct *si = swap_type_to_swap_info(type);  in get_swap_page_of_type()  local
1085 	if (!si)  in get_swap_page_of_type()
1088 	spin_lock(&si->lock);  in get_swap_page_of_type()
1089 	if (si->flags & SWP_WRITEOK) {  in get_swap_page_of_type()
1092 		offset = scan_swap_map(si, 1);  in get_swap_page_of_type()
1094 			spin_unlock(&si->lock);  in get_swap_page_of_type()
1099 	spin_unlock(&si->lock);  in get_swap_page_of_type()
1251 	struct swap_info_struct *si;  in get_swap_device()  local
1256 	si = swp_swap_info(entry);  in get_swap_device()
1257 	if (!si)  in get_swap_device()
1261 	if (!(si->flags & SWP_VALID))  in get_swap_device()
1264 	if (offset >= si->max)  in get_swap_device()
1267 	return si;  in get_swap_device()
1330 	struct swap_info_struct *si;  in put_swap_page()  local
1336 	si = _swap_info_get(entry);  in put_swap_page()
1337 	if (!si)  in put_swap_page()
1340 	ci = lock_cluster_or_swap_info(si, offset);  in put_swap_page()
1343 		map = si->swap_map + offset;  in put_swap_page()
1352 			unlock_cluster_or_swap_info(si, ci);  in put_swap_page()
1353 			spin_lock(&si->lock);  in put_swap_page()
1355 			swap_free_cluster(si, idx);  in put_swap_page()
1356 			spin_unlock(&si->lock);  in put_swap_page()
1361 		if (!__swap_entry_free_locked(si, offset + i, SWAP_HAS_CACHE)) {  in put_swap_page()
1362 			unlock_cluster_or_swap_info(si, ci);  in put_swap_page()
1366 			lock_cluster_or_swap_info(si, offset);  in put_swap_page()
1369 	unlock_cluster_or_swap_info(si, ci);  in put_swap_page()
1375 	struct swap_info_struct *si;  in split_swap_cluster()  local
1379 	si = _swap_info_get(entry);  in split_swap_cluster()
1380 	if (!si)  in split_swap_cluster()
1382 	ci = lock_cluster(si, offset);  in split_swap_cluster()
1450 	struct swap_info_struct *si;  in __swap_count()  local
1454 	si = get_swap_device(entry);  in __swap_count()
1455 	if (si) {  in __swap_count()
1456 		count = swap_count(si->swap_map[offset]);  in __swap_count()
1457 		put_swap_device(si);  in __swap_count()
1462 static int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry)  in swap_swapcount()  argument
1468 	ci = lock_cluster_or_swap_info(si, offset);  in swap_swapcount()
1469 	count = swap_count(si->swap_map[offset]);  in swap_swapcount()
1470 	unlock_cluster_or_swap_info(si, ci);  in swap_swapcount()
1482 	struct swap_info_struct *si;  in __swp_swapcount()  local
1484 	si = get_swap_device(entry);  in __swp_swapcount()
1485 	if (si) {  in __swp_swapcount()
1486 		count = swap_swapcount(si, entry);  in __swp_swapcount()
1487 		put_swap_device(si);  in __swp_swapcount()
1538 static bool swap_page_trans_huge_swapped(struct swap_info_struct *si,  in swap_page_trans_huge_swapped()  argument
1542 	unsigned char *map = si->swap_map;  in swap_page_trans_huge_swapped()
1548 	ci = lock_cluster_or_swap_info(si, offset);  in swap_page_trans_huge_swapped()
1561 	unlock_cluster_or_swap_info(si, ci);  in swap_page_trans_huge_swapped()
1568 	struct swap_info_struct *si;  in page_swapped()  local
1575 	si = _swap_info_get(entry);  in page_swapped()
1576 	if (si)  in page_swapped()
1577 		return swap_page_trans_huge_swapped(si, entry);  in page_swapped()
1586 	struct swap_info_struct *si;  in page_trans_huge_map_swapcount()  local
1610 		si = _swap_info_get(entry);  in page_trans_huge_map_swapcount()
1611 		if (si) {  in page_trans_huge_map_swapcount()
1612 			map = si->swap_map;  in page_trans_huge_map_swapcount()
1617 		ci = lock_cluster(si, offset);  in page_trans_huge_map_swapcount()
1809 	struct swap_info_struct *si = swap_type_to_swap_info(type);  in swapdev_block()  local
1811 	if (!si || !(si->flags & SWP_WRITEOK))  in swapdev_block()
1917 	struct swap_info_struct *si;  in unuse_pte_range()  local
1922 	si = swap_info[type];  in unuse_pte_range()
1935 		if (frontswap && !frontswap_test(si, offset))  in unuse_pte_range()
1939 		swap_map = &si->swap_map[offset];  in unuse_pte_range()
2092 static unsigned int find_next_to_unuse(struct swap_info_struct *si,  in find_next_to_unuse()  argument
2104 	for (i = prev + 1; i < si->max; i++) {  in find_next_to_unuse()
2105 		count = READ_ONCE(si->swap_map[i]);  in find_next_to_unuse()
2107 			if (!frontswap || frontswap_test(si, i))  in find_next_to_unuse()
2113 	if (i == si->max)  in find_next_to_unuse()
2130 	struct swap_info_struct *si = swap_info[type];  in try_to_unuse()  local
2135 	if (!si->inuse_pages)  in try_to_unuse()
2151 	while (si->inuse_pages &&  in try_to_unuse()
2180 	while (si->inuse_pages &&  in try_to_unuse()
2182 	       (i = find_next_to_unuse(si, i, frontswap)) != 0) {  in try_to_unuse()
2222 	if (si->inuse_pages) {  in try_to_unuse()
2567 		struct swap_info_struct *si = p;  in SYSCALL_DEFINE1()  local
2570 		plist_for_each_entry_continue(si, &swap_active_head, list) {  in SYSCALL_DEFINE1()
2571 			si->prio++;  in SYSCALL_DEFINE1()
2572 			si->list.prio--;  in SYSCALL_DEFINE1()
2574 				if (si->avail_lists[nid].prio != 1)  in SYSCALL_DEFINE1()
2575 					si->avail_lists[nid].prio--;  in SYSCALL_DEFINE1()
2711 	struct swap_info_struct *si;  in swap_start()  local
2720 	for (type = 0; (si = swap_type_to_swap_info(type)); type++) {  in swap_start()
2721 		if (!(si->flags & SWP_USED) || !si->swap_map)  in swap_start()
2724 			return si;  in swap_start()
2732 	struct swap_info_struct *si = v;  in swap_next()  local
2738 		type = si->type + 1;  in swap_next()
2740 	for (; (si = swap_type_to_swap_info(type)); type++) {  in swap_next()
2741 		if (!(si->flags & SWP_USED) || !si->swap_map)  in swap_next()
2744 		return si;  in swap_next()
2757 	struct swap_info_struct *si = v;  in swap_show()  local
2761 	if (si == SEQ_START_TOKEN) {  in swap_show()
2766 	file = si->swap_file;  in swap_show()
2772 			si->pages << (PAGE_SHIFT - 10),  in swap_show()
2773 			si->inuse_pages << (PAGE_SHIFT - 10),  in swap_show()
2774 			si->prio);  in swap_show()
3092 static bool swap_discardable(struct swap_info_struct *si)  in swap_discardable()  argument
3094 	struct request_queue *q = bdev_get_queue(si->bdev);  in swap_discardable()
3357 		struct swap_info_struct *si = swap_info[type];  in si_swapinfo()  local
3359 		if ((si->flags & SWP_USED) && !(si->flags & SWP_WRITEOK))  in si_swapinfo()
3360 			nr_to_be_unused += si->inuse_pages;  in si_swapinfo()
3524 	struct swap_info_struct *si;  in add_swap_count_continuation()  local
3539 	si = get_swap_device(entry);  in add_swap_count_continuation()
3540 	if (!si) {  in add_swap_count_continuation()
3547 	spin_lock(&si->lock);  in add_swap_count_continuation()
3551 	ci = lock_cluster(si, offset);  in add_swap_count_continuation()
3553 	count = si->swap_map[offset] & ~SWAP_HAS_CACHE;  in add_swap_count_continuation()
3574 	head = vmalloc_to_page(si->swap_map + offset);  in add_swap_count_continuation()
3577 	spin_lock(&si->cont_lock);  in add_swap_count_continuation()
3586 		si->flags |= SWP_CONTINUED;  in add_swap_count_continuation()
3614 	spin_unlock(&si->cont_lock);  in add_swap_count_continuation()
3617 	spin_unlock(&si->lock);  in add_swap_count_continuation()
3618 	put_swap_device(si);  in add_swap_count_continuation()
3634 static bool swap_count_continued(struct swap_info_struct *si,  in swap_count_continued()  argument
3642 	head = vmalloc_to_page(si->swap_map + offset);  in swap_count_continued()
3648 	spin_lock(&si->cont_lock);  in swap_count_continued()
3714 	spin_unlock(&si->cont_lock);  in swap_count_continued()
3722 static void free_swap_count_continuations(struct swap_info_struct *si)  in free_swap_count_continuations()  argument
3726 	for (offset = 0; offset < si->max; offset += PAGE_SIZE) {  in free_swap_count_continuations()
3728 		head = vmalloc_to_page(si->swap_map + offset);  in free_swap_count_continuations()
3744 	struct swap_info_struct *si, *next;  in mem_cgroup_throttle_swaprate()  local
3759 	plist_for_each_entry_safe(si, next, &swap_avail_heads[node],  in mem_cgroup_throttle_swaprate()
3761 		if (si->bdev) {  in mem_cgroup_throttle_swaprate()
3762 			blkcg_schedule_throttle(bdev_get_queue(si->bdev),  in mem_cgroup_throttle_swaprate()