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