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 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 resposible 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 resposible 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 */