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 #include <linux/xarray.h> 15 16 struct mem_cgroup; 17 18 /* list_lru_walk_cb has to always return one of those */ 19 enum lru_status { 20 LRU_REMOVED, /* item removed from list */ 21 LRU_REMOVED_RETRY, /* item removed, but lock has been 22 dropped and reacquired */ 23 LRU_ROTATE, /* item referenced, give another pass */ 24 LRU_SKIP, /* item cannot be locked, skip */ 25 LRU_RETRY, /* item not freeable. May drop the lock 26 internally, but has to return locked. */ 27 LRU_STOP, /* stop lru list walking. May drop the lock 28 internally, but has to return locked. */ 29 }; 30 31 struct list_lru_one { 32 struct list_head list; 33 /* may become negative during memcg reparenting */ 34 long nr_items; 35 /* protects all fields above */ 36 spinlock_t lock; 37 }; 38 39 struct list_lru_memcg { 40 struct rcu_head rcu; 41 /* array of per cgroup per node lists, indexed by node id */ 42 struct list_lru_one node[]; 43 }; 44 45 struct list_lru_node { 46 /* global list, used for the root cgroup in cgroup aware lrus */ 47 struct list_lru_one lru; 48 atomic_long_t nr_items; 49 } ____cacheline_aligned_in_smp; 50 51 struct list_lru { 52 struct list_lru_node *node; 53 #ifdef CONFIG_MEMCG 54 struct list_head list; 55 int shrinker_id; 56 bool memcg_aware; 57 struct xarray xa; 58 #endif 59 #ifdef CONFIG_LOCKDEP 60 struct lock_class_key *key; 61 #endif 62 }; 63 64 void list_lru_destroy(struct list_lru *lru); 65 int __list_lru_init(struct list_lru *lru, bool memcg_aware, 66 struct shrinker *shrinker); 67 68 #define list_lru_init(lru) \ 69 __list_lru_init((lru), false, NULL) 70 #define list_lru_init_memcg(lru, shrinker) \ 71 __list_lru_init((lru), true, shrinker) 72 73 static inline int list_lru_init_memcg_key(struct list_lru *lru, struct shrinker *shrinker, 74 struct lock_class_key *key) 75 { 76 #ifdef CONFIG_LOCKDEP 77 lru->key = key; 78 #endif 79 return list_lru_init_memcg(lru, shrinker); 80 } 81 82 int memcg_list_lru_alloc(struct mem_cgroup *memcg, struct list_lru *lru, 83 gfp_t gfp); 84 void memcg_reparent_list_lrus(struct mem_cgroup *memcg, struct mem_cgroup *parent); 85 86 /** 87 * list_lru_add: add an element to the lru list's tail 88 * @lru: the lru pointer 89 * @item: the item to be added. 90 * @nid: the node id of the sublist to add the item to. 91 * @memcg: the cgroup of the sublist to add the item to. 92 * 93 * If the element is already part of a list, this function returns doing 94 * nothing. Therefore the caller does not need to keep state about whether or 95 * not the element already belongs in the list and is allowed to lazy update 96 * it. Note however that this is valid for *a* list, not *this* list. If 97 * the caller organize itself in a way that elements can be in more than 98 * one type of list, it is up to the caller to fully remove the item from 99 * the previous list (with list_lru_del() for instance) before moving it 100 * to @lru. 101 * 102 * Return: true if the list was updated, false otherwise 103 */ 104 bool list_lru_add(struct list_lru *lru, struct list_head *item, int nid, 105 struct mem_cgroup *memcg); 106 107 /** 108 * list_lru_add_obj: add an element to the lru list's tail 109 * @lru: the lru pointer 110 * @item: the item to be added. 111 * 112 * This function is similar to list_lru_add(), but the NUMA node and the 113 * memcg of the sublist is determined by @item list_head. This assumption is 114 * valid for slab objects LRU such as dentries, inodes, etc. 115 * 116 * Return value: true if the list was updated, false otherwise 117 */ 118 bool list_lru_add_obj(struct list_lru *lru, struct list_head *item); 119 120 /** 121 * list_lru_del: delete an element from the lru list 122 * @lru: the lru pointer 123 * @item: the item to be deleted. 124 * @nid: the node id of the sublist to delete the item from. 125 * @memcg: the cgroup of the sublist to delete the item from. 126 * 127 * This function works analogously as list_lru_add() in terms of list 128 * manipulation. The comments about an element already pertaining to 129 * a list are also valid for list_lru_del(). 130 * 131 * Return: true if the list was updated, false otherwise 132 */ 133 bool list_lru_del(struct list_lru *lru, struct list_head *item, int nid, 134 struct mem_cgroup *memcg); 135 136 /** 137 * list_lru_del_obj: delete an element from the lru list 138 * @lru: the lru pointer 139 * @item: the item to be deleted. 140 * 141 * This function is similar to list_lru_del(), but the NUMA node and the 142 * memcg of the sublist is determined by @item list_head. This assumption is 143 * valid for slab objects LRU such as dentries, inodes, etc. 144 * 145 * Return value: true if the list was updated, false otherwise. 146 */ 147 bool list_lru_del_obj(struct list_lru *lru, struct list_head *item); 148 149 /** 150 * list_lru_count_one: return the number of objects currently held by @lru 151 * @lru: the lru pointer. 152 * @nid: the node id to count from. 153 * @memcg: the cgroup to count from. 154 * 155 * There is no guarantee that the list is not updated while the count is being 156 * computed. Callers that want such a guarantee need to provide an outer lock. 157 * 158 * Return: 0 for empty lists, otherwise the number of objects 159 * currently held by @lru. 160 */ 161 unsigned long list_lru_count_one(struct list_lru *lru, 162 int nid, struct mem_cgroup *memcg); 163 unsigned long list_lru_count_node(struct list_lru *lru, int nid); 164 165 static inline unsigned long list_lru_shrink_count(struct list_lru *lru, 166 struct shrink_control *sc) 167 { 168 return list_lru_count_one(lru, sc->nid, sc->memcg); 169 } 170 171 static inline unsigned long list_lru_count(struct list_lru *lru) 172 { 173 long count = 0; 174 int nid; 175 176 for_each_node_state(nid, N_NORMAL_MEMORY) 177 count += list_lru_count_node(lru, nid); 178 179 return count; 180 } 181 182 void list_lru_isolate(struct list_lru_one *list, struct list_head *item); 183 void list_lru_isolate_move(struct list_lru_one *list, struct list_head *item, 184 struct list_head *head); 185 186 typedef enum lru_status (*list_lru_walk_cb)(struct list_head *item, 187 struct list_lru_one *list, void *cb_arg); 188 189 /** 190 * list_lru_walk_one: walk a @lru, isolating and disposing freeable items. 191 * @lru: the lru pointer. 192 * @nid: the node id to scan from. 193 * @memcg: the cgroup to scan from. 194 * @isolate: callback function that is responsible for deciding what to do with 195 * the item currently being scanned 196 * @cb_arg: opaque type that will be passed to @isolate 197 * @nr_to_walk: how many items to scan. 198 * 199 * This function will scan all elements in a particular @lru, calling the 200 * @isolate callback for each of those items, along with the current list 201 * spinlock and a caller-provided opaque. The @isolate callback can choose to 202 * drop the lock internally, but *must* return with the lock held. The callback 203 * will return an enum lru_status telling the @lru infrastructure what to 204 * do with the object being scanned. 205 * 206 * Please note that @nr_to_walk does not mean how many objects will be freed, 207 * just how many objects will be scanned. 208 * 209 * Return: the number of objects effectively removed from the LRU. 210 */ 211 unsigned long list_lru_walk_one(struct list_lru *lru, 212 int nid, struct mem_cgroup *memcg, 213 list_lru_walk_cb isolate, void *cb_arg, 214 unsigned long *nr_to_walk); 215 /** 216 * list_lru_walk_one_irq: walk a @lru, isolating and disposing freeable items. 217 * @lru: the lru pointer. 218 * @nid: the node id to scan from. 219 * @memcg: the cgroup to scan from. 220 * @isolate: callback function that is responsible for deciding what to do with 221 * the item currently being scanned 222 * @cb_arg: opaque type that will be passed to @isolate 223 * @nr_to_walk: how many items to scan. 224 * 225 * Same as list_lru_walk_one() except that the spinlock is acquired with 226 * spin_lock_irq(). 227 */ 228 unsigned long list_lru_walk_one_irq(struct list_lru *lru, 229 int nid, struct mem_cgroup *memcg, 230 list_lru_walk_cb isolate, void *cb_arg, 231 unsigned long *nr_to_walk); 232 unsigned long list_lru_walk_node(struct list_lru *lru, int nid, 233 list_lru_walk_cb isolate, void *cb_arg, 234 unsigned long *nr_to_walk); 235 236 static inline unsigned long 237 list_lru_shrink_walk(struct list_lru *lru, struct shrink_control *sc, 238 list_lru_walk_cb isolate, void *cb_arg) 239 { 240 return list_lru_walk_one(lru, sc->nid, sc->memcg, isolate, cb_arg, 241 &sc->nr_to_scan); 242 } 243 244 static inline unsigned long 245 list_lru_shrink_walk_irq(struct list_lru *lru, struct shrink_control *sc, 246 list_lru_walk_cb isolate, void *cb_arg) 247 { 248 return list_lru_walk_one_irq(lru, sc->nid, sc->memcg, isolate, cb_arg, 249 &sc->nr_to_scan); 250 } 251 252 static inline unsigned long 253 list_lru_walk(struct list_lru *lru, list_lru_walk_cb isolate, 254 void *cb_arg, unsigned long nr_to_walk) 255 { 256 long isolated = 0; 257 int nid; 258 259 for_each_node_state(nid, N_NORMAL_MEMORY) { 260 isolated += list_lru_walk_node(lru, nid, isolate, 261 cb_arg, &nr_to_walk); 262 if (nr_to_walk <= 0) 263 break; 264 } 265 return isolated; 266 } 267 #endif /* _LRU_LIST_H */ 268