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Diffstat (limited to 'include/linux/list_lru.h')
| -rw-r--r-- | include/linux/list_lru.h | 289 |
1 files changed, 289 insertions, 0 deletions
diff --git a/include/linux/list_lru.h b/include/linux/list_lru.h new file mode 100644 index 000000000000..fe739d35a864 --- /dev/null +++ b/include/linux/list_lru.h @@ -0,0 +1,289 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (c) 2013 Red Hat, Inc. and Parallels Inc. All rights reserved. + * Authors: David Chinner and Glauber Costa + * + * Generic LRU infrastructure + */ +#ifndef _LRU_LIST_H +#define _LRU_LIST_H + +#include <linux/list.h> +#include <linux/nodemask.h> +#include <linux/shrinker.h> +#include <linux/xarray.h> + +struct mem_cgroup; + +/* list_lru_walk_cb has to always return one of those */ +enum lru_status { + LRU_REMOVED, /* item removed from list */ + LRU_REMOVED_RETRY, /* item removed, but lock has been + dropped and reacquired */ + LRU_ROTATE, /* item referenced, give another pass */ + LRU_SKIP, /* item cannot be locked, skip */ + LRU_RETRY, /* item not freeable. May drop the lock + internally, but has to return locked. */ + LRU_STOP, /* stop lru list walking. May drop the lock + internally, but has to return locked. */ +}; + +struct list_lru_one { + struct list_head list; + /* may become negative during memcg reparenting */ + long nr_items; + /* protects all fields above */ + spinlock_t lock; +}; + +struct list_lru_memcg { + struct rcu_head rcu; + /* array of per cgroup per node lists, indexed by node id */ + struct list_lru_one node[]; +}; + +struct list_lru_node { + /* global list, used for the root cgroup in cgroup aware lrus */ + struct list_lru_one lru; + atomic_long_t nr_items; +} ____cacheline_aligned_in_smp; + +struct list_lru { + struct list_lru_node *node; +#ifdef CONFIG_MEMCG + struct list_head list; + int shrinker_id; + bool memcg_aware; + struct xarray xa; +#endif +#ifdef CONFIG_LOCKDEP + struct lock_class_key *key; +#endif +}; + +void list_lru_destroy(struct list_lru *lru); +int __list_lru_init(struct list_lru *lru, bool memcg_aware, + struct shrinker *shrinker); + +#define list_lru_init(lru) \ + __list_lru_init((lru), false, NULL) +#define list_lru_init_memcg(lru, shrinker) \ + __list_lru_init((lru), true, shrinker) + +static inline int list_lru_init_memcg_key(struct list_lru *lru, struct shrinker *shrinker, + struct lock_class_key *key) +{ +#ifdef CONFIG_LOCKDEP + lru->key = key; +#endif + return list_lru_init_memcg(lru, shrinker); +} + +int memcg_list_lru_alloc(struct mem_cgroup *memcg, struct list_lru *lru, + gfp_t gfp); +void memcg_reparent_list_lrus(struct mem_cgroup *memcg, struct mem_cgroup *parent); + +/** + * list_lru_add: add an element to the lru list's tail + * @lru: the lru pointer + * @item: the item to be added. + * @nid: the node id of the sublist to add the item to. + * @memcg: the cgroup of the sublist to add the item to. + * + * If the element is already part of a list, this function returns doing + * nothing. This means that it is not necessary to keep state about whether or + * not the element already belongs in the list. That said, this logic only + * works if the item is in *this* list. If the item might be in some other + * list, then you cannot rely on this check and you must remove it from the + * other list before trying to insert it. + * + * The lru list consists of many sublists internally; the @nid and @memcg + * parameters are used to determine which sublist to insert the item into. + * It's important to use the right value of @nid and @memcg when deleting the + * item, since it might otherwise get deleted from the wrong sublist. + * + * This also applies when attempting to insert the item multiple times - if + * the item is currently in one sublist and you call list_lru_add() again, you + * must pass the right @nid and @memcg parameters so that the same sublist is + * used. + * + * You must ensure that the memcg is not freed during this call (e.g., with + * rcu or by taking a css refcnt). + * + * Return: true if the list was updated, false otherwise + */ +bool list_lru_add(struct list_lru *lru, struct list_head *item, int nid, + struct mem_cgroup *memcg); + +/** + * list_lru_add_obj: add an element to the lru list's tail + * @lru: the lru pointer + * @item: the item to be added. + * + * This function is similar to list_lru_add(), but the NUMA node and the + * memcg of the sublist is determined by @item list_head. This assumption is + * valid for slab objects LRU such as dentries, inodes, etc. + * + * Return: true if the list was updated, false otherwise + */ +bool list_lru_add_obj(struct list_lru *lru, struct list_head *item); + +/** + * list_lru_del: delete an element from the lru list + * @lru: the lru pointer + * @item: the item to be deleted. + * @nid: the node id of the sublist to delete the item from. + * @memcg: the cgroup of the sublist to delete the item from. + * + * This function works analogously as list_lru_add() in terms of list + * manipulation. + * + * The comments in list_lru_add() about an element already being in a list are + * also valid for list_lru_del(), that is, you can delete an item that has + * already been removed or never been added. However, if the item is in a + * list, it must be in *this* list, and you must pass the right value of @nid + * and @memcg so that the right sublist is used. + * + * You must ensure that the memcg is not freed during this call (e.g., with + * rcu or by taking a css refcnt). When a memcg is deleted, list_lru entries + * are automatically moved to the parent memcg. This is done in a race-free + * way, so during deletion of an memcg both the old and new memcg will resolve + * to the same sublist internally. + * + * Return: true if the list was updated, false otherwise + */ +bool list_lru_del(struct list_lru *lru, struct list_head *item, int nid, + struct mem_cgroup *memcg); + +/** + * list_lru_del_obj: delete an element from the lru list + * @lru: the lru pointer + * @item: the item to be deleted. + * + * This function is similar to list_lru_del(), but the NUMA node and the + * memcg of the sublist is determined by @item list_head. This assumption is + * valid for slab objects LRU such as dentries, inodes, etc. + * + * Return: true if the list was updated, false otherwise. + */ +bool list_lru_del_obj(struct list_lru *lru, struct list_head *item); + +/** + * list_lru_count_one: return the number of objects currently held by @lru + * @lru: the lru pointer. + * @nid: the node id to count from. + * @memcg: the cgroup to count from. + * + * There is no guarantee that the list is not updated while the count is being + * computed. Callers that want such a guarantee need to provide an outer lock. + * + * Return: 0 for empty lists, otherwise the number of objects + * currently held by @lru. + */ +unsigned long list_lru_count_one(struct list_lru *lru, + int nid, struct mem_cgroup *memcg); +unsigned long list_lru_count_node(struct list_lru *lru, int nid); + +static inline unsigned long list_lru_shrink_count(struct list_lru *lru, + struct shrink_control *sc) +{ + return list_lru_count_one(lru, sc->nid, sc->memcg); +} + +static inline unsigned long list_lru_count(struct list_lru *lru) +{ + long count = 0; + int nid; + + for_each_node_state(nid, N_NORMAL_MEMORY) + count += list_lru_count_node(lru, nid); + + return count; +} + +void list_lru_isolate(struct list_lru_one *list, struct list_head *item); +void list_lru_isolate_move(struct list_lru_one *list, struct list_head *item, + struct list_head *head); + +typedef enum lru_status (*list_lru_walk_cb)(struct list_head *item, + struct list_lru_one *list, void *cb_arg); + +/** + * list_lru_walk_one: walk a @lru, isolating and disposing freeable items. + * @lru: the lru pointer. + * @nid: the node id to scan from. + * @memcg: the cgroup to scan from. + * @isolate: callback function that is responsible for deciding what to do with + * the item currently being scanned + * @cb_arg: opaque type that will be passed to @isolate + * @nr_to_walk: how many items to scan. + * + * This function will scan all elements in a particular @lru, calling the + * @isolate callback for each of those items, along with the current list + * spinlock and a caller-provided opaque. The @isolate callback can choose to + * drop the lock internally, but *must* return with the lock held. The callback + * will return an enum lru_status telling the @lru infrastructure what to + * do with the object being scanned. + * + * Please note that @nr_to_walk does not mean how many objects will be freed, + * just how many objects will be scanned. + * + * Return: the number of objects effectively removed from the LRU. + */ +unsigned long list_lru_walk_one(struct list_lru *lru, + int nid, struct mem_cgroup *memcg, + list_lru_walk_cb isolate, void *cb_arg, + unsigned long *nr_to_walk); +/** + * list_lru_walk_one_irq: walk a @lru, isolating and disposing freeable items. + * @lru: the lru pointer. + * @nid: the node id to scan from. + * @memcg: the cgroup to scan from. + * @isolate: callback function that is responsible for deciding what to do with + * the item currently being scanned + * @cb_arg: opaque type that will be passed to @isolate + * @nr_to_walk: how many items to scan. + * + * Same as list_lru_walk_one() except that the spinlock is acquired with + * spin_lock_irq(). + */ +unsigned long list_lru_walk_one_irq(struct list_lru *lru, + int nid, struct mem_cgroup *memcg, + list_lru_walk_cb isolate, void *cb_arg, + unsigned long *nr_to_walk); +unsigned long list_lru_walk_node(struct list_lru *lru, int nid, + list_lru_walk_cb isolate, void *cb_arg, + unsigned long *nr_to_walk); + +static inline unsigned long +list_lru_shrink_walk(struct list_lru *lru, struct shrink_control *sc, + list_lru_walk_cb isolate, void *cb_arg) +{ + return list_lru_walk_one(lru, sc->nid, sc->memcg, isolate, cb_arg, + &sc->nr_to_scan); +} + +static inline unsigned long +list_lru_shrink_walk_irq(struct list_lru *lru, struct shrink_control *sc, + list_lru_walk_cb isolate, void *cb_arg) +{ + return list_lru_walk_one_irq(lru, sc->nid, sc->memcg, isolate, cb_arg, + &sc->nr_to_scan); +} + +static inline unsigned long +list_lru_walk(struct list_lru *lru, list_lru_walk_cb isolate, + void *cb_arg, unsigned long nr_to_walk) +{ + long isolated = 0; + int nid; + + for_each_node_state(nid, N_NORMAL_MEMORY) { + isolated += list_lru_walk_node(lru, nid, isolate, + cb_arg, &nr_to_walk); + if (nr_to_walk <= 0) + break; + } + return isolated; +} +#endif /* _LRU_LIST_H */ |