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/* 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. */
};
struct list_lru_one {
struct list_head list;
/* may become negative during memcg reparenting */
long nr_items;
};
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 {
/* protects all lists on the node, including per cgroup */
spinlock_t lock;
/* global list, used for the root cgroup in cgroup aware lrus */
struct list_lru_one lru;
long nr_items;
} ____cacheline_aligned_in_smp;
struct list_lru {
struct list_lru_node *node;
#ifdef CONFIG_MEMCG_KMEM
struct list_head list;
int shrinker_id;
bool memcg_aware;
struct xarray xa;
#endif
};
void list_lru_destroy(struct list_lru *lru);
int __list_lru_init(struct list_lru *lru, bool memcg_aware,
struct lock_class_key *key, struct shrinker *shrinker);
#define list_lru_init(lru) \
__list_lru_init((lru), false, NULL, NULL)
#define list_lru_init_key(lru, key) \
__list_lru_init((lru), false, (key), NULL)
#define list_lru_init_memcg(lru, shrinker) \
__list_lru_init((lru), true, NULL, 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. Therefore the caller does not need to keep state about whether or
* not the element already belongs in the list and is allowed to lazy update
* it. Note however that this is valid for *a* list, not *this* list. If
* the caller organize itself in a way that elements can be in more than
* one type of list, it is up to the caller to fully remove the item from
* the previous list (with list_lru_del() for instance) before moving it
* to @lru.
*
* 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 value: 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 about an element already pertaining to
* a list are also valid for list_lru_del().
*
* 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 value: 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);
/**
* list_lru_putback: undo list_lru_isolate
* @lru: the lru pointer.
* @item: the item to put back.
* @nid: the node id of the sublist to put the item back to.
* @memcg: the cgroup of the sublist to put the item back to.
*
* Put back an isolated item into its original LRU. Note that unlike
* list_lru_add, this does not increment the node LRU count (as
* list_lru_isolate does not originally decrement this count).
*
* Since we might have dropped the LRU lock in between, recompute list_lru_one
* from the node's id and memcg.
*/
void list_lru_putback(struct list_lru *lru, struct list_head *item, int nid,
struct mem_cgroup *memcg);
typedef enum lru_status (*list_lru_walk_cb)(struct list_head *item,
struct list_lru_one *list, spinlock_t *lock, 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 */