1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * Copyright (c) 2013 Red Hat, Inc. and Parallels Inc. All rights reserved. 4 * Authors: David Chinner and Glauber Costa 5 * 6 * Generic LRU infrastructure 7 */ 8 #ifndef _LRU_LIST_H 9 #define _LRU_LIST_H 10 11 #include <linux/list.h> 12 #include <linux/nodemask.h> 13 #include <linux/shrinker.h> 14 15 struct mem_cgroup; 16 17 /* list_lru_walk_cb has to always return one of those */ 18 enum lru_status { 19 LRU_REMOVED, /* item removed from list */ 20 LRU_REMOVED_RETRY, /* item removed, but lock has been 21 dropped and reacquired */ 22 LRU_ROTATE, /* item referenced, give another pass */ 23 LRU_SKIP, /* item cannot be locked, skip */ 24 LRU_RETRY, /* item not freeable. May drop the lock 25 internally, but has to return locked. */ 26 }; 27 28 struct list_lru_one { 29 struct list_head list; 30 /* may become negative during memcg reparenting */ 31 long nr_items; 32 }; 33 34 struct list_lru_memcg { 35 struct rcu_head rcu; 36 /* array of per cgroup lists, indexed by memcg_cache_id */ 37 struct list_lru_one *lru[0]; 38 }; 39 40 struct list_lru_node { 41 /* protects all lists on the node, including per cgroup */ 42 spinlock_t lock; 43 /* global list, used for the root cgroup in cgroup aware lrus */ 44 struct list_lru_one lru; 45 #ifdef CONFIG_MEMCG_KMEM 46 /* for cgroup aware lrus points to per cgroup lists, otherwise NULL */ 47 struct list_lru_memcg __rcu *memcg_lrus; 48 #endif 49 long nr_items; 50 } ____cacheline_aligned_in_smp; 51 52 struct list_lru { 53 struct list_lru_node *node; 54 #ifdef CONFIG_MEMCG_KMEM 55 struct list_head list; 56 int shrinker_id; 57 #endif 58 }; 59 60 void list_lru_destroy(struct list_lru *lru); 61 int __list_lru_init(struct list_lru *lru, bool memcg_aware, 62 struct lock_class_key *key, struct shrinker *shrinker); 63 64 #define list_lru_init(lru) \ 65 __list_lru_init((lru), false, NULL, NULL) 66 #define list_lru_init_key(lru, key) \ 67 __list_lru_init((lru), false, (key), NULL) 68 #define list_lru_init_memcg(lru, shrinker) \ 69 __list_lru_init((lru), true, NULL, shrinker) 70 71 int memcg_update_all_list_lrus(int num_memcgs); 72 void memcg_drain_all_list_lrus(int src_idx, struct mem_cgroup *dst_memcg); 73 74 /** 75 * list_lru_add: add an element to the lru list's tail 76 * @list_lru: the lru pointer 77 * @item: the item to be added. 78 * 79 * If the element is already part of a list, this function returns doing 80 * nothing. Therefore the caller does not need to keep state about whether or 81 * not the element already belongs in the list and is allowed to lazy update 82 * it. Note however that this is valid for *a* list, not *this* list. If 83 * the caller organize itself in a way that elements can be in more than 84 * one type of list, it is up to the caller to fully remove the item from 85 * the previous list (with list_lru_del() for instance) before moving it 86 * to @list_lru 87 * 88 * Return value: true if the list was updated, false otherwise 89 */ 90 bool list_lru_add(struct list_lru *lru, struct list_head *item); 91 92 /** 93 * list_lru_del: delete an element to the lru list 94 * @list_lru: the lru pointer 95 * @item: the item to be deleted. 96 * 97 * This function works analogously as list_lru_add in terms of list 98 * manipulation. The comments about an element already pertaining to 99 * a list are also valid for list_lru_del. 100 * 101 * Return value: true if the list was updated, false otherwise 102 */ 103 bool list_lru_del(struct list_lru *lru, struct list_head *item); 104 105 /** 106 * list_lru_count_one: return the number of objects currently held by @lru 107 * @lru: the lru pointer. 108 * @nid: the node id to count from. 109 * @memcg: the cgroup to count from. 110 * 111 * Always return a non-negative number, 0 for empty lists. There is no 112 * guarantee that the list is not updated while the count is being computed. 113 * Callers that want such a guarantee need to provide an outer lock. 114 */ 115 unsigned long list_lru_count_one(struct list_lru *lru, 116 int nid, struct mem_cgroup *memcg); 117 unsigned long list_lru_count_node(struct list_lru *lru, int nid); 118 119 static inline unsigned long list_lru_shrink_count(struct list_lru *lru, 120 struct shrink_control *sc) 121 { 122 return list_lru_count_one(lru, sc->nid, sc->memcg); 123 } 124 125 static inline unsigned long list_lru_count(struct list_lru *lru) 126 { 127 long count = 0; 128 int nid; 129 130 for_each_node_state(nid, N_NORMAL_MEMORY) 131 count += list_lru_count_node(lru, nid); 132 133 return count; 134 } 135 136 void list_lru_isolate(struct list_lru_one *list, struct list_head *item); 137 void list_lru_isolate_move(struct list_lru_one *list, struct list_head *item, 138 struct list_head *head); 139 140 typedef enum lru_status (*list_lru_walk_cb)(struct list_head *item, 141 struct list_lru_one *list, spinlock_t *lock, void *cb_arg); 142 143 /** 144 * list_lru_walk_one: walk a list_lru, isolating and disposing freeable items. 145 * @lru: the lru pointer. 146 * @nid: the node id to scan from. 147 * @memcg: the cgroup to scan from. 148 * @isolate: callback function that is resposible for deciding what to do with 149 * the item currently being scanned 150 * @cb_arg: opaque type that will be passed to @isolate 151 * @nr_to_walk: how many items to scan. 152 * 153 * This function will scan all elements in a particular list_lru, calling the 154 * @isolate callback for each of those items, along with the current list 155 * spinlock and a caller-provided opaque. The @isolate callback can choose to 156 * drop the lock internally, but *must* return with the lock held. The callback 157 * will return an enum lru_status telling the list_lru infrastructure what to 158 * do with the object being scanned. 159 * 160 * Please note that nr_to_walk does not mean how many objects will be freed, 161 * just how many objects will be scanned. 162 * 163 * Return value: the number of objects effectively removed from the LRU. 164 */ 165 unsigned long list_lru_walk_one(struct list_lru *lru, 166 int nid, struct mem_cgroup *memcg, 167 list_lru_walk_cb isolate, void *cb_arg, 168 unsigned long *nr_to_walk); 169 /** 170 * list_lru_walk_one_irq: walk a list_lru, isolating and disposing freeable items. 171 * @lru: the lru pointer. 172 * @nid: the node id to scan from. 173 * @memcg: the cgroup to scan from. 174 * @isolate: callback function that is resposible for deciding what to do with 175 * the item currently being scanned 176 * @cb_arg: opaque type that will be passed to @isolate 177 * @nr_to_walk: how many items to scan. 178 * 179 * Same as @list_lru_walk_one except that the spinlock is acquired with 180 * spin_lock_irq(). 181 */ 182 unsigned long list_lru_walk_one_irq(struct list_lru *lru, 183 int nid, struct mem_cgroup *memcg, 184 list_lru_walk_cb isolate, void *cb_arg, 185 unsigned long *nr_to_walk); 186 unsigned long list_lru_walk_node(struct list_lru *lru, int nid, 187 list_lru_walk_cb isolate, void *cb_arg, 188 unsigned long *nr_to_walk); 189 190 static inline unsigned long 191 list_lru_shrink_walk(struct list_lru *lru, struct shrink_control *sc, 192 list_lru_walk_cb isolate, void *cb_arg) 193 { 194 return list_lru_walk_one(lru, sc->nid, sc->memcg, isolate, cb_arg, 195 &sc->nr_to_scan); 196 } 197 198 static inline unsigned long 199 list_lru_shrink_walk_irq(struct list_lru *lru, struct shrink_control *sc, 200 list_lru_walk_cb isolate, void *cb_arg) 201 { 202 return list_lru_walk_one_irq(lru, sc->nid, sc->memcg, isolate, cb_arg, 203 &sc->nr_to_scan); 204 } 205 206 static inline unsigned long 207 list_lru_walk(struct list_lru *lru, list_lru_walk_cb isolate, 208 void *cb_arg, unsigned long nr_to_walk) 209 { 210 long isolated = 0; 211 int nid; 212 213 for_each_node_state(nid, N_NORMAL_MEMORY) { 214 isolated += list_lru_walk_node(lru, nid, isolate, 215 cb_arg, &nr_to_walk); 216 if (nr_to_walk <= 0) 217 break; 218 } 219 return isolated; 220 } 221 #endif /* _LRU_LIST_H */ 222