151 	/* Always discard instead of demoting to lower tier memory */
1529 		 * Reclaiming directly from top tier nodes is not often desired  in shrink_folio_list()
1531 		 * should be reclaimed from lower tier nodes and demoted from  in shrink_folio_list()
1532 		 * top tier nodes.  in shrink_folio_list()
1534 		 * However, disabling reclaim from top tier nodes entirely  in shrink_folio_list()
1535 		 * would cause ooms in edge scenarios where lower tier memory  in shrink_folio_list()
1538 		 * from top tier nodes in proactive reclaim though as that is  in shrink_folio_list()
3045  * The P term is refaulted/(evicted+protected) from a tier in the generation
3050  * The setpoint (SP) is always the first tier of one type; the process variable
3051  * (PV) is either any tier of the other type or any other tier of the same
3067 static void read_ctrl_pos(struct lruvec *lruvec, int type, int tier, int gain,  in read_ctrl_pos()  argument
3073 	pos->refaulted = lrugen->avg_refaulted[type][tier] +  in read_ctrl_pos()
3074 			 atomic_long_read(&lrugen->refaulted[hist][type][tier]);  in read_ctrl_pos()
3075 	pos->total = lrugen->avg_total[type][tier] +  in read_ctrl_pos()
3076 		     atomic_long_read(&lrugen->evicted[hist][type][tier]);  in read_ctrl_pos()
3077 	if (tier)  in read_ctrl_pos()
3078 		pos->total += lrugen->protected[hist][type][tier - 1];  in read_ctrl_pos()
3084 	int hist, tier;  in reset_ctrl_pos()  local
3096 	for (tier = 0; tier < MAX_NR_TIERS; tier++) {  in reset_ctrl_pos()
3100 			sum = lrugen->avg_refaulted[type][tier] +  in reset_ctrl_pos()
3101 			      atomic_long_read(&lrugen->refaulted[hist][type][tier]);  in reset_ctrl_pos()
3102 			WRITE_ONCE(lrugen->avg_refaulted[type][tier], sum / 2);  in reset_ctrl_pos()
3104 			sum = lrugen->avg_total[type][tier] +  in reset_ctrl_pos()
3105 			      atomic_long_read(&lrugen->evicted[hist][type][tier]);  in reset_ctrl_pos()
3106 			if (tier)  in reset_ctrl_pos()
3107 				sum += lrugen->protected[hist][type][tier - 1];  in reset_ctrl_pos()
3108 			WRITE_ONCE(lrugen->avg_total[type][tier], sum / 2);  in reset_ctrl_pos()
3112 			atomic_long_set(&lrugen->refaulted[hist][type][tier], 0);  in reset_ctrl_pos()
3113 			atomic_long_set(&lrugen->evicted[hist][type][tier], 0);  in reset_ctrl_pos()
3114 			if (tier)  in reset_ctrl_pos()
3115 				WRITE_ONCE(lrugen->protected[hist][type][tier - 1], 0);  in reset_ctrl_pos()
4298 	int tier = lru_tier_from_refs(refs);  in sort_folio()  local
4320 	if (tier > tier_idx || refs == BIT(LRU_REFS_WIDTH)) {  in sort_folio()
4326 		WRITE_ONCE(lrugen->protected[hist][type][tier - 1],  in sort_folio()
4327 			   lrugen->protected[hist][type][tier - 1] + delta);  in sort_folio()
4384 		       int type, int tier, struct list_head *list)  in scan_folios()  argument
4421 			if (sort_folio(lruvec, folio, sc, tier))  in scan_folios()
4466 	int tier;  in get_tier_idx()  local
4471 	 * This value is chosen because any other tier would have at least twice  in get_tier_idx()
4472 	 * as many refaults as the first tier.  in get_tier_idx()
4475 	for (tier = 1; tier < MAX_NR_TIERS; tier++) {  in get_tier_idx()
4476 		read_ctrl_pos(lruvec, type, tier, 2, &pv);  in get_tier_idx()
4481 	return tier - 1;  in get_tier_idx()
4486 	int type, tier;  in get_type_to_scan()  local
4491 	 * Compare the first tier of anon with that of file to determine which  in get_type_to_scan()
4493 	 * with the first tier of the other type to determine the last tier (of  in get_type_to_scan()
4501 	for (tier = 1; tier < MAX_NR_TIERS; tier++) {  in get_type_to_scan()
4502 		read_ctrl_pos(lruvec, type, tier, gain[type], &pv);  in get_type_to_scan()
4507 	*tier_idx = tier - 1;  in get_type_to_scan()
4518 	int tier = -1;  in isolate_folios()  local
4540 		type = get_type_to_scan(lruvec, swappiness, &tier);  in isolate_folios()
4543 		if (tier < 0)  in isolate_folios()
4544 			tier = get_tier_idx(lruvec, type);  in isolate_folios()
4546 		scanned = scan_folios(lruvec, sc, type, tier, list);  in isolate_folios()
4551 		tier = -1;  in isolate_folios()
5255 	int type, tier;  in lru_gen_seq_show_full()  local
5260 	for (tier = 0; tier < MAX_NR_TIERS; tier++) {  in lru_gen_seq_show_full()
5261 		seq_printf(m, "            %10d", tier);  in lru_gen_seq_show_full()
5268 				n[0] = READ_ONCE(lrugen->avg_refaulted[type][tier]);  in lru_gen_seq_show_full()
5269 				n[1] = READ_ONCE(lrugen->avg_total[type][tier]);  in lru_gen_seq_show_full()
5272 				n[0] = atomic_long_read(&lrugen->refaulted[hist][type][tier]);  in lru_gen_seq_show_full()
5273 				n[1] = atomic_long_read(&lrugen->evicted[hist][type][tier]);  in lru_gen_seq_show_full()
5274 				if (tier)  in lru_gen_seq_show_full()
5275 					n[2] = READ_ONCE(lrugen->protected[hist][type][tier - 1]);  in lru_gen_seq_show_full()