2 * Copyright (c) 2013 Red Hat, Inc. and Parallels Inc. All rights reserved.
3 * Authors: David Chinner and Glauber Costa
5 * Generic LRU infrastructure
10 #include <linux/list.h>
11 #include <linux/nodemask.h>
12 #include <linux/shrinker.h>
16 /* list_lru_walk_cb has to always return one of those */
18 LRU_REMOVED, /* item removed from list */
19 LRU_REMOVED_RETRY, /* item removed, but lock has been
20 dropped and reacquired */
21 LRU_ROTATE, /* item referenced, give another pass */
22 LRU_SKIP, /* item cannot be locked, skip */
23 LRU_RETRY, /* item not freeable. May drop the lock
24 internally, but has to return locked. */
28 struct list_head list;
29 /* kept as signed so we can catch imbalance bugs */
33 struct list_lru_memcg {
34 /* array of per cgroup lists, indexed by memcg_cache_id */
35 struct list_lru_one *lru[0];
38 struct list_lru_node {
39 /* protects all lists on the node, including per cgroup */
41 /* global list, used for the root cgroup in cgroup aware lrus */
42 struct list_lru_one lru;
43 #ifdef CONFIG_MEMCG_KMEM
44 /* for cgroup aware lrus points to per cgroup lists, otherwise NULL */
45 struct list_lru_memcg *memcg_lrus;
47 } ____cacheline_aligned_in_smp;
50 struct list_lru_node *node;
51 #ifdef CONFIG_MEMCG_KMEM
52 struct list_head list;
56 void list_lru_destroy(struct list_lru *lru);
57 int __list_lru_init(struct list_lru *lru, bool memcg_aware,
58 struct lock_class_key *key);
60 #define list_lru_init(lru) __list_lru_init((lru), false, NULL)
61 #define list_lru_init_key(lru, key) __list_lru_init((lru), false, (key))
62 #define list_lru_init_memcg(lru) __list_lru_init((lru), true, NULL)
64 int memcg_update_all_list_lrus(int num_memcgs);
67 * list_lru_add: add an element to the lru list's tail
68 * @list_lru: the lru pointer
69 * @item: the item to be added.
71 * If the element is already part of a list, this function returns doing
72 * nothing. Therefore the caller does not need to keep state about whether or
73 * not the element already belongs in the list and is allowed to lazy update
74 * it. Note however that this is valid for *a* list, not *this* list. If
75 * the caller organize itself in a way that elements can be in more than
76 * one type of list, it is up to the caller to fully remove the item from
77 * the previous list (with list_lru_del() for instance) before moving it
80 * Return value: true if the list was updated, false otherwise
82 bool list_lru_add(struct list_lru *lru, struct list_head *item);
85 * list_lru_del: delete an element to the lru list
86 * @list_lru: the lru pointer
87 * @item: the item to be deleted.
89 * This function works analogously as list_lru_add in terms of list
90 * manipulation. The comments about an element already pertaining to
91 * a list are also valid for list_lru_del.
93 * Return value: true if the list was updated, false otherwise
95 bool list_lru_del(struct list_lru *lru, struct list_head *item);
98 * list_lru_count_one: return the number of objects currently held by @lru
99 * @lru: the lru pointer.
100 * @nid: the node id to count from.
101 * @memcg: the cgroup to count from.
103 * Always return a non-negative number, 0 for empty lists. There is no
104 * guarantee that the list is not updated while the count is being computed.
105 * Callers that want such a guarantee need to provide an outer lock.
107 unsigned long list_lru_count_one(struct list_lru *lru,
108 int nid, struct mem_cgroup *memcg);
109 unsigned long list_lru_count_node(struct list_lru *lru, int nid);
111 static inline unsigned long list_lru_shrink_count(struct list_lru *lru,
112 struct shrink_control *sc)
114 return list_lru_count_one(lru, sc->nid, sc->memcg);
117 static inline unsigned long list_lru_count(struct list_lru *lru)
122 for_each_node_state(nid, N_NORMAL_MEMORY)
123 count += list_lru_count_node(lru, nid);
128 void list_lru_isolate(struct list_lru_one *list, struct list_head *item);
129 void list_lru_isolate_move(struct list_lru_one *list, struct list_head *item,
130 struct list_head *head);
132 typedef enum lru_status (*list_lru_walk_cb)(struct list_head *item,
133 struct list_lru_one *list, spinlock_t *lock, void *cb_arg);
136 * list_lru_walk_one: walk a list_lru, isolating and disposing freeable items.
137 * @lru: the lru pointer.
138 * @nid: the node id to scan from.
139 * @memcg: the cgroup to scan from.
140 * @isolate: callback function that is resposible for deciding what to do with
141 * the item currently being scanned
142 * @cb_arg: opaque type that will be passed to @isolate
143 * @nr_to_walk: how many items to scan.
145 * This function will scan all elements in a particular list_lru, calling the
146 * @isolate callback for each of those items, along with the current list
147 * spinlock and a caller-provided opaque. The @isolate callback can choose to
148 * drop the lock internally, but *must* return with the lock held. The callback
149 * will return an enum lru_status telling the list_lru infrastructure what to
150 * do with the object being scanned.
152 * Please note that nr_to_walk does not mean how many objects will be freed,
153 * just how many objects will be scanned.
155 * Return value: the number of objects effectively removed from the LRU.
157 unsigned long list_lru_walk_one(struct list_lru *lru,
158 int nid, struct mem_cgroup *memcg,
159 list_lru_walk_cb isolate, void *cb_arg,
160 unsigned long *nr_to_walk);
161 unsigned long list_lru_walk_node(struct list_lru *lru, int nid,
162 list_lru_walk_cb isolate, void *cb_arg,
163 unsigned long *nr_to_walk);
165 static inline unsigned long
166 list_lru_shrink_walk(struct list_lru *lru, struct shrink_control *sc,
167 list_lru_walk_cb isolate, void *cb_arg)
169 return list_lru_walk_one(lru, sc->nid, sc->memcg, isolate, cb_arg,
173 static inline unsigned long
174 list_lru_walk(struct list_lru *lru, list_lru_walk_cb isolate,
175 void *cb_arg, unsigned long nr_to_walk)
180 for_each_node_state(nid, N_NORMAL_MEMORY) {
181 isolated += list_lru_walk_node(lru, nid, isolate,
182 cb_arg, &nr_to_walk);
188 #endif /* _LRU_LIST_H */