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[]; 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 bool memcg_aware; 58 #endif 59 }; 60 61 void list_lru_destroy(struct list_lru *lru); 62 int __list_lru_init(struct list_lru *lru, bool memcg_aware, 63 struct lock_class_key *key, struct shrinker *shrinker); 64 65 #define list_lru_init(lru) \ 66 __list_lru_init((lru), false, NULL, NULL) 67 #define list_lru_init_key(lru, key) \ 68 __list_lru_init((lru), false, (key), NULL) 69 #define list_lru_init_memcg(lru, shrinker) \ 70 __list_lru_init((lru), true, NULL, shrinker) 71 72 int memcg_update_all_list_lrus(int num_memcgs); 73 void memcg_drain_all_list_lrus(int src_idx, struct mem_cgroup *dst_memcg); 74 75 /** 76 * list_lru_add: add an element to the lru list's tail 77 * @list_lru: the lru pointer 78 * @item: the item to be added. 79 * 80 * If the element is already part of a list, this function returns doing 81 * nothing. Therefore the caller does not need to keep state about whether or 82 * not the element already belongs in the list and is allowed to lazy update 83 * it. Note however that this is valid for *a* list, not *this* list. If 84 * the caller organize itself in a way that elements can be in more than 85 * one type of list, it is up to the caller to fully remove the item from 86 * the previous list (with list_lru_del() for instance) before moving it 87 * to @list_lru 88 * 89 * Return value: true if the list was updated, false otherwise 90 */ 91 bool list_lru_add(struct list_lru *lru, struct list_head *item); 92 93 /** 94 * list_lru_del: delete an element to the lru list 95 * @list_lru: the lru pointer 96 * @item: the item to be deleted. 97 * 98 * This function works analogously as list_lru_add in terms of list 99 * manipulation. The comments about an element already pertaining to 100 * a list are also valid for list_lru_del. 101 * 102 * Return value: true if the list was updated, false otherwise 103 */ 104 bool list_lru_del(struct list_lru *lru, struct list_head *item); 105 106 /** 107 * list_lru_count_one: return the number of objects currently held by @lru 108 * @lru: the lru pointer. 109 * @nid: the node id to count from. 110 * @memcg: the cgroup to count from. 111 * 112 * Always return a non-negative number, 0 for empty lists. There is no 113 * guarantee that the list is not updated while the count is being computed. 114 * Callers that want such a guarantee need to provide an outer lock. 115 */ 116 unsigned long list_lru_count_one(struct list_lru *lru, 117 int nid, struct mem_cgroup *memcg); 118 unsigned long list_lru_count_node(struct list_lru *lru, int nid); 119 120 static inline unsigned long list_lru_shrink_count(struct list_lru *lru, 121 struct shrink_control *sc) 122 { 123 return list_lru_count_one(lru, sc->nid, sc->memcg); 124 } 125 126 static inline unsigned long list_lru_count(struct list_lru *lru) 127 { 128 long count = 0; 129 int nid; 130 131 for_each_node_state(nid, N_NORMAL_MEMORY) 132 count += list_lru_count_node(lru, nid); 133 134 return count; 135 } 136 137 void list_lru_isolate(struct list_lru_one *list, struct list_head *item); 138 void list_lru_isolate_move(struct list_lru_one *list, struct list_head *item, 139 struct list_head *head); 140 141 typedef enum lru_status (*list_lru_walk_cb)(struct list_head *item, 142 struct list_lru_one *list, spinlock_t *lock, void *cb_arg); 143 144 /** 145 * list_lru_walk_one: walk a list_lru, isolating and disposing freeable items. 146 * @lru: the lru pointer. 147 * @nid: the node id to scan from. 148 * @memcg: the cgroup to scan from. 149 * @isolate: callback function that is responsible for deciding what to do with 150 * the item currently being scanned 151 * @cb_arg: opaque type that will be passed to @isolate 152 * @nr_to_walk: how many items to scan. 153 * 154 * This function will scan all elements in a particular list_lru, calling the 155 * @isolate callback for each of those items, along with the current list 156 * spinlock and a caller-provided opaque. The @isolate callback can choose to 157 * drop the lock internally, but *must* return with the lock held. The callback 158 * will return an enum lru_status telling the list_lru infrastructure what to 159 * do with the object being scanned. 160 * 161 * Please note that nr_to_walk does not mean how many objects will be freed, 162 * just how many objects will be scanned. 163 * 164 * Return value: the number of objects effectively removed from the LRU. 165 */ 166 unsigned long list_lru_walk_one(struct list_lru *lru, 167 int nid, struct mem_cgroup *memcg, 168 list_lru_walk_cb isolate, void *cb_arg, 169 unsigned long *nr_to_walk); 170 /** 171 * list_lru_walk_one_irq: walk a list_lru, isolating and disposing freeable items. 172 * @lru: the lru pointer. 173 * @nid: the node id to scan from. 174 * @memcg: the cgroup to scan from. 175 * @isolate: callback function that is responsible for deciding what to do with 176 * the item currently being scanned 177 * @cb_arg: opaque type that will be passed to @isolate 178 * @nr_to_walk: how many items to scan. 179 * 180 * Same as @list_lru_walk_one except that the spinlock is acquired with 181 * spin_lock_irq(). 182 */ 183 unsigned long list_lru_walk_one_irq(struct list_lru *lru, 184 int nid, struct mem_cgroup *memcg, 185 list_lru_walk_cb isolate, void *cb_arg, 186 unsigned long *nr_to_walk); 187 unsigned long list_lru_walk_node(struct list_lru *lru, int nid, 188 list_lru_walk_cb isolate, void *cb_arg, 189 unsigned long *nr_to_walk); 190 191 static inline unsigned long 192 list_lru_shrink_walk(struct list_lru *lru, struct shrink_control *sc, 193 list_lru_walk_cb isolate, void *cb_arg) 194 { 195 return list_lru_walk_one(lru, sc->nid, sc->memcg, isolate, cb_arg, 196 &sc->nr_to_scan); 197 } 198 199 static inline unsigned long 200 list_lru_shrink_walk_irq(struct list_lru *lru, struct shrink_control *sc, 201 list_lru_walk_cb isolate, void *cb_arg) 202 { 203 return list_lru_walk_one_irq(lru, sc->nid, sc->memcg, isolate, cb_arg, 204 &sc->nr_to_scan); 205 } 206 207 static inline unsigned long 208 list_lru_walk(struct list_lru *lru, list_lru_walk_cb isolate, 209 void *cb_arg, unsigned long nr_to_walk) 210 { 211 long isolated = 0; 212 int nid; 213 214 for_each_node_state(nid, N_NORMAL_MEMORY) { 215 isolated += list_lru_walk_node(lru, nid, isolate, 216 cb_arg, &nr_to_walk); 217 if (nr_to_walk <= 0) 218 break; 219 } 220 return isolated; 221 } 222 #endif /* _LRU_LIST_H */ 223