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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 : 0 : static inline unsigned long list_lru_shrink_count(struct list_lru *lru,
121 : : struct shrink_control *sc)
122 : : {
123 : 0 : return list_lru_count_one(lru, sc->nid, sc->memcg);
124 : : }
125 : :
126 : 48 : static inline unsigned long list_lru_count(struct list_lru *lru)
127 : : {
128 : 48 : long count = 0;
129 : 48 : int nid;
130 : :
131 [ + + ]: 144 : for_each_node_state(nid, N_NORMAL_MEMORY)
132 : 48 : count += list_lru_count_node(lru, nid);
133 : :
134 : 48 : 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 : 0 : list_lru_shrink_walk(struct list_lru *lru, struct shrink_control *sc,
193 : : list_lru_walk_cb isolate, void *cb_arg)
194 : : {
195 : 0 : 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 : 0 : list_lru_shrink_walk_irq(struct list_lru *lru, struct shrink_control *sc,
201 : : list_lru_walk_cb isolate, void *cb_arg)
202 : : {
203 : 0 : 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 : 48 : list_lru_walk(struct list_lru *lru, list_lru_walk_cb isolate,
209 : : void *cb_arg, unsigned long nr_to_walk)
210 : : {
211 : 48 : long isolated = 0;
212 : 48 : int nid;
213 : :
214 [ + + ]: 192 : for_each_node_state(nid, N_NORMAL_MEMORY) {
215 : 48 : isolated += list_lru_walk_node(lru, nid, isolate,
216 : : cb_arg, &nr_to_walk);
217 [ + - ]: 48 : if (nr_to_walk <= 0)
218 : : break;
219 : : }
220 : 48 : return isolated;
221 : : }
222 : : #endif /* _LRU_LIST_H */
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