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
15struct mem_cgroup;
16
17/* list_lru_walk_cb has to always return one of those */
18enum 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
28struct list_lru_one {
29 struct list_head list;
30 /* may become negative during memcg reparenting */
31 long nr_items;
32};
33
34struct 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
40struct 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
52struct list_lru {
53 struct list_lru_node *node;
54#ifdef CONFIG_MEMCG_KMEM
55 struct list_head list;
56 int shrinker_id;
57#endif
58};
59
60void list_lru_destroy(struct list_lru *lru);
61int __list_lru_init(struct list_lru *lru, bool memcg_aware,
62 struct lock_class_key *key, struct shrinker *shrinker);
63
64#define list_lru_init(lru) \
65 __list_lru_init((lru), false, NULL, NULL)
66#define list_lru_init_key(lru, key) \
67 __list_lru_init((lru), false, (key), NULL)
68#define list_lru_init_memcg(lru, shrinker) \
69 __list_lru_init((lru), true, NULL, shrinker)
70
71int memcg_update_all_list_lrus(int num_memcgs);
72void memcg_drain_all_list_lrus(int src_idx, struct mem_cgroup *dst_memcg);
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 */
90bool 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 */
103bool 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 */
115unsigned long list_lru_count_one(struct list_lru *lru,
116 int nid, struct mem_cgroup *memcg);
117unsigned long list_lru_count_node(struct list_lru *lru, int nid);
118
119static inline unsigned long list_lru_shrink_count(struct list_lru *lru,
120 struct shrink_control *sc)
121{
122 return list_lru_count_one(lru, sc->nid, sc->memcg);
123}
124
125static inline unsigned long list_lru_count(struct list_lru *lru)
126{
127 long count = 0;
128 int nid;
129
130 for_each_node_state(nid, N_NORMAL_MEMORY)
131 count += list_lru_count_node(lru, nid);
132
133 return count;
134}
135
136void list_lru_isolate(struct list_lru_one *list, struct list_head *item);
137void list_lru_isolate_move(struct list_lru_one *list, struct list_head *item,
138 struct list_head *head);
139
140typedef 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 resposible 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 */
165unsigned 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 resposible 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 */
182unsigned 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);
186unsigned 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
190static inline unsigned long
191list_lru_shrink_walk(struct list_lru *lru, struct shrink_control *sc,
192 list_lru_walk_cb isolate, void *cb_arg)
193{
194 return list_lru_walk_one(lru, sc->nid, sc->memcg, isolate, cb_arg,
195 &sc->nr_to_scan);
196}
197
198static inline unsigned long
199list_lru_shrink_walk_irq(struct list_lru *lru, struct shrink_control *sc,
200 list_lru_walk_cb isolate, void *cb_arg)
201{
202 return list_lru_walk_one_irq(lru, sc->nid, sc->memcg, isolate, cb_arg,
203 &sc->nr_to_scan);
204}
205
206static inline unsigned long
207list_lru_walk(struct list_lru *lru, list_lru_walk_cb isolate,
208 void *cb_arg, unsigned long nr_to_walk)
209{
210 long isolated = 0;
211 int nid;
212
213 for_each_node_state(nid, N_NORMAL_MEMORY) {
214 isolated += list_lru_walk_node(lru, nid, isolate,
215 cb_arg, &nr_to_walk);
216 if (nr_to_walk <= 0)
217 break;
218 }
219 return isolated;
220}
221#endif /* _LRU_LIST_H */
222