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- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * Copyright (c) 2013 Red Hat, Inc. and Parallels Inc. All rights reserved.
- * Authors: David Chinner and Glauber Costa
- *
- * Generic LRU infrastructure
- */
- #include <linux/kernel.h>
- #include <linux/module.h>
- #include <linux/mm.h>
- #include <linux/list_lru.h>
- #include <linux/slab.h>
- #include <linux/mutex.h>
- #include <linux/memcontrol.h>
- #include "slab.h"
- #include "internal.h"
- #ifdef CONFIG_MEMCG_KMEM
- static LIST_HEAD(memcg_list_lrus);
- static DEFINE_MUTEX(list_lrus_mutex);
- static inline bool list_lru_memcg_aware(struct list_lru *lru)
- {
- return lru->memcg_aware;
- }
- static void list_lru_register(struct list_lru *lru)
- {
- if (!list_lru_memcg_aware(lru))
- return;
- mutex_lock(&list_lrus_mutex);
- list_add(&lru->list, &memcg_list_lrus);
- mutex_unlock(&list_lrus_mutex);
- }
- static void list_lru_unregister(struct list_lru *lru)
- {
- if (!list_lru_memcg_aware(lru))
- return;
- mutex_lock(&list_lrus_mutex);
- list_del(&lru->list);
- mutex_unlock(&list_lrus_mutex);
- }
- static int lru_shrinker_id(struct list_lru *lru)
- {
- return lru->shrinker_id;
- }
- static inline struct list_lru_one *
- list_lru_from_memcg_idx(struct list_lru *lru, int nid, int idx)
- {
- if (list_lru_memcg_aware(lru) && idx >= 0) {
- struct list_lru_memcg *mlru = xa_load(&lru->xa, idx);
- return mlru ? &mlru->node[nid] : NULL;
- }
- return &lru->node[nid].lru;
- }
- static inline struct list_lru_one *
- list_lru_from_kmem(struct list_lru *lru, int nid, void *ptr,
- struct mem_cgroup **memcg_ptr)
- {
- struct list_lru_node *nlru = &lru->node[nid];
- struct list_lru_one *l = &nlru->lru;
- struct mem_cgroup *memcg = NULL;
- if (!list_lru_memcg_aware(lru))
- goto out;
- memcg = mem_cgroup_from_slab_obj(ptr);
- if (!memcg)
- goto out;
- l = list_lru_from_memcg_idx(lru, nid, memcg_kmem_id(memcg));
- out:
- if (memcg_ptr)
- *memcg_ptr = memcg;
- return l;
- }
- #else
- static void list_lru_register(struct list_lru *lru)
- {
- }
- static void list_lru_unregister(struct list_lru *lru)
- {
- }
- static int lru_shrinker_id(struct list_lru *lru)
- {
- return -1;
- }
- static inline bool list_lru_memcg_aware(struct list_lru *lru)
- {
- return false;
- }
- static inline struct list_lru_one *
- list_lru_from_memcg_idx(struct list_lru *lru, int nid, int idx)
- {
- return &lru->node[nid].lru;
- }
- static inline struct list_lru_one *
- list_lru_from_kmem(struct list_lru *lru, int nid, void *ptr,
- struct mem_cgroup **memcg_ptr)
- {
- if (memcg_ptr)
- *memcg_ptr = NULL;
- return &lru->node[nid].lru;
- }
- #endif /* CONFIG_MEMCG_KMEM */
- bool list_lru_add(struct list_lru *lru, struct list_head *item)
- {
- int nid = page_to_nid(virt_to_page(item));
- struct list_lru_node *nlru = &lru->node[nid];
- struct mem_cgroup *memcg;
- struct list_lru_one *l;
- spin_lock(&nlru->lock);
- if (list_empty(item)) {
- l = list_lru_from_kmem(lru, nid, item, &memcg);
- list_add_tail(item, &l->list);
- /* Set shrinker bit if the first element was added */
- if (!l->nr_items++)
- set_shrinker_bit(memcg, nid,
- lru_shrinker_id(lru));
- nlru->nr_items++;
- spin_unlock(&nlru->lock);
- return true;
- }
- spin_unlock(&nlru->lock);
- return false;
- }
- EXPORT_SYMBOL_GPL(list_lru_add);
- bool list_lru_del(struct list_lru *lru, struct list_head *item)
- {
- int nid = page_to_nid(virt_to_page(item));
- struct list_lru_node *nlru = &lru->node[nid];
- struct list_lru_one *l;
- spin_lock(&nlru->lock);
- if (!list_empty(item)) {
- l = list_lru_from_kmem(lru, nid, item, NULL);
- list_del_init(item);
- l->nr_items--;
- nlru->nr_items--;
- spin_unlock(&nlru->lock);
- return true;
- }
- spin_unlock(&nlru->lock);
- return false;
- }
- EXPORT_SYMBOL_GPL(list_lru_del);
- void list_lru_isolate(struct list_lru_one *list, struct list_head *item)
- {
- list_del_init(item);
- list->nr_items--;
- }
- EXPORT_SYMBOL_GPL(list_lru_isolate);
- void list_lru_isolate_move(struct list_lru_one *list, struct list_head *item,
- struct list_head *head)
- {
- list_move(item, head);
- list->nr_items--;
- }
- EXPORT_SYMBOL_GPL(list_lru_isolate_move);
- unsigned long list_lru_count_one(struct list_lru *lru,
- int nid, struct mem_cgroup *memcg)
- {
- struct list_lru_one *l;
- long count;
- rcu_read_lock();
- l = list_lru_from_memcg_idx(lru, nid, memcg_kmem_id(memcg));
- count = l ? READ_ONCE(l->nr_items) : 0;
- rcu_read_unlock();
- if (unlikely(count < 0))
- count = 0;
- return count;
- }
- EXPORT_SYMBOL_GPL(list_lru_count_one);
- unsigned long list_lru_count_node(struct list_lru *lru, int nid)
- {
- struct list_lru_node *nlru;
- nlru = &lru->node[nid];
- return nlru->nr_items;
- }
- EXPORT_SYMBOL_GPL(list_lru_count_node);
- static unsigned long
- __list_lru_walk_one(struct list_lru *lru, int nid, int memcg_idx,
- list_lru_walk_cb isolate, void *cb_arg,
- unsigned long *nr_to_walk)
- {
- struct list_lru_node *nlru = &lru->node[nid];
- struct list_lru_one *l;
- struct list_head *item, *n;
- unsigned long isolated = 0;
- restart:
- l = list_lru_from_memcg_idx(lru, nid, memcg_idx);
- if (!l)
- goto out;
- list_for_each_safe(item, n, &l->list) {
- enum lru_status ret;
- /*
- * decrement nr_to_walk first so that we don't livelock if we
- * get stuck on large numbers of LRU_RETRY items
- */
- if (!*nr_to_walk)
- break;
- --*nr_to_walk;
- ret = isolate(item, l, &nlru->lock, cb_arg);
- switch (ret) {
- case LRU_REMOVED_RETRY:
- assert_spin_locked(&nlru->lock);
- fallthrough;
- case LRU_REMOVED:
- isolated++;
- nlru->nr_items--;
- /*
- * If the lru lock has been dropped, our list
- * traversal is now invalid and so we have to
- * restart from scratch.
- */
- if (ret == LRU_REMOVED_RETRY)
- goto restart;
- break;
- case LRU_ROTATE:
- list_move_tail(item, &l->list);
- break;
- case LRU_SKIP:
- break;
- case LRU_RETRY:
- /*
- * The lru lock has been dropped, our list traversal is
- * now invalid and so we have to restart from scratch.
- */
- assert_spin_locked(&nlru->lock);
- goto restart;
- default:
- BUG();
- }
- }
- out:
- return isolated;
- }
- 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)
- {
- struct list_lru_node *nlru = &lru->node[nid];
- unsigned long ret;
- spin_lock(&nlru->lock);
- ret = __list_lru_walk_one(lru, nid, memcg_kmem_id(memcg), isolate,
- cb_arg, nr_to_walk);
- spin_unlock(&nlru->lock);
- return ret;
- }
- EXPORT_SYMBOL_GPL(list_lru_walk_one);
- 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)
- {
- struct list_lru_node *nlru = &lru->node[nid];
- unsigned long ret;
- spin_lock_irq(&nlru->lock);
- ret = __list_lru_walk_one(lru, nid, memcg_kmem_id(memcg), isolate,
- cb_arg, nr_to_walk);
- spin_unlock_irq(&nlru->lock);
- return ret;
- }
- 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)
- {
- long isolated = 0;
- isolated += list_lru_walk_one(lru, nid, NULL, isolate, cb_arg,
- nr_to_walk);
- #ifdef CONFIG_MEMCG_KMEM
- if (*nr_to_walk > 0 && list_lru_memcg_aware(lru)) {
- struct list_lru_memcg *mlru;
- unsigned long index;
- xa_for_each(&lru->xa, index, mlru) {
- struct list_lru_node *nlru = &lru->node[nid];
- spin_lock(&nlru->lock);
- isolated += __list_lru_walk_one(lru, nid, index,
- isolate, cb_arg,
- nr_to_walk);
- spin_unlock(&nlru->lock);
- if (*nr_to_walk <= 0)
- break;
- }
- }
- #endif
- return isolated;
- }
- EXPORT_SYMBOL_GPL(list_lru_walk_node);
- static void init_one_lru(struct list_lru_one *l)
- {
- INIT_LIST_HEAD(&l->list);
- l->nr_items = 0;
- }
- #ifdef CONFIG_MEMCG_KMEM
- static struct list_lru_memcg *memcg_init_list_lru_one(gfp_t gfp)
- {
- int nid;
- struct list_lru_memcg *mlru;
- mlru = kmalloc(struct_size(mlru, node, nr_node_ids), gfp);
- if (!mlru)
- return NULL;
- for_each_node(nid)
- init_one_lru(&mlru->node[nid]);
- return mlru;
- }
- static void memcg_list_lru_free(struct list_lru *lru, int src_idx)
- {
- struct list_lru_memcg *mlru = xa_erase_irq(&lru->xa, src_idx);
- /*
- * The __list_lru_walk_one() can walk the list of this node.
- * We need kvfree_rcu() here. And the walking of the list
- * is under lru->node[nid]->lock, which can serve as a RCU
- * read-side critical section.
- */
- if (mlru)
- kvfree_rcu(mlru, rcu);
- }
- static inline void memcg_init_list_lru(struct list_lru *lru, bool memcg_aware)
- {
- if (memcg_aware)
- xa_init_flags(&lru->xa, XA_FLAGS_LOCK_IRQ);
- lru->memcg_aware = memcg_aware;
- }
- static void memcg_destroy_list_lru(struct list_lru *lru)
- {
- XA_STATE(xas, &lru->xa, 0);
- struct list_lru_memcg *mlru;
- if (!list_lru_memcg_aware(lru))
- return;
- xas_lock_irq(&xas);
- xas_for_each(&xas, mlru, ULONG_MAX) {
- kfree(mlru);
- xas_store(&xas, NULL);
- }
- xas_unlock_irq(&xas);
- }
- static void memcg_reparent_list_lru_node(struct list_lru *lru, int nid,
- int src_idx, struct mem_cgroup *dst_memcg)
- {
- struct list_lru_node *nlru = &lru->node[nid];
- int dst_idx = dst_memcg->kmemcg_id;
- struct list_lru_one *src, *dst;
- /*
- * Since list_lru_{add,del} may be called under an IRQ-safe lock,
- * we have to use IRQ-safe primitives here to avoid deadlock.
- */
- spin_lock_irq(&nlru->lock);
- src = list_lru_from_memcg_idx(lru, nid, src_idx);
- if (!src)
- goto out;
- dst = list_lru_from_memcg_idx(lru, nid, dst_idx);
- list_splice_init(&src->list, &dst->list);
- if (src->nr_items) {
- dst->nr_items += src->nr_items;
- set_shrinker_bit(dst_memcg, nid, lru_shrinker_id(lru));
- src->nr_items = 0;
- }
- out:
- spin_unlock_irq(&nlru->lock);
- }
- static void memcg_reparent_list_lru(struct list_lru *lru,
- int src_idx, struct mem_cgroup *dst_memcg)
- {
- int i;
- for_each_node(i)
- memcg_reparent_list_lru_node(lru, i, src_idx, dst_memcg);
- memcg_list_lru_free(lru, src_idx);
- }
- void memcg_reparent_list_lrus(struct mem_cgroup *memcg, struct mem_cgroup *parent)
- {
- struct cgroup_subsys_state *css;
- struct list_lru *lru;
- int src_idx = memcg->kmemcg_id;
- /*
- * Change kmemcg_id of this cgroup and all its descendants to the
- * parent's id, and then move all entries from this cgroup's list_lrus
- * to ones of the parent.
- *
- * After we have finished, all list_lrus corresponding to this cgroup
- * are guaranteed to remain empty. So we can safely free this cgroup's
- * list lrus in memcg_list_lru_free().
- *
- * Changing ->kmemcg_id to the parent can prevent memcg_list_lru_alloc()
- * from allocating list lrus for this cgroup after memcg_list_lru_free()
- * call.
- */
- rcu_read_lock();
- css_for_each_descendant_pre(css, &memcg->css) {
- struct mem_cgroup *child;
- child = mem_cgroup_from_css(css);
- WRITE_ONCE(child->kmemcg_id, parent->kmemcg_id);
- }
- rcu_read_unlock();
- mutex_lock(&list_lrus_mutex);
- list_for_each_entry(lru, &memcg_list_lrus, list)
- memcg_reparent_list_lru(lru, src_idx, parent);
- mutex_unlock(&list_lrus_mutex);
- }
- static inline bool memcg_list_lru_allocated(struct mem_cgroup *memcg,
- struct list_lru *lru)
- {
- int idx = memcg->kmemcg_id;
- return idx < 0 || xa_load(&lru->xa, idx);
- }
- int memcg_list_lru_alloc(struct mem_cgroup *memcg, struct list_lru *lru,
- gfp_t gfp)
- {
- int i;
- unsigned long flags;
- struct list_lru_memcg_table {
- struct list_lru_memcg *mlru;
- struct mem_cgroup *memcg;
- } *table;
- XA_STATE(xas, &lru->xa, 0);
- if (!list_lru_memcg_aware(lru) || memcg_list_lru_allocated(memcg, lru))
- return 0;
- gfp &= GFP_RECLAIM_MASK;
- table = kmalloc_array(memcg->css.cgroup->level, sizeof(*table), gfp);
- if (!table)
- return -ENOMEM;
- /*
- * Because the list_lru can be reparented to the parent cgroup's
- * list_lru, we should make sure that this cgroup and all its
- * ancestors have allocated list_lru_memcg.
- */
- for (i = 0; memcg; memcg = parent_mem_cgroup(memcg), i++) {
- if (memcg_list_lru_allocated(memcg, lru))
- break;
- table[i].memcg = memcg;
- table[i].mlru = memcg_init_list_lru_one(gfp);
- if (!table[i].mlru) {
- while (i--)
- kfree(table[i].mlru);
- kfree(table);
- return -ENOMEM;
- }
- }
- xas_lock_irqsave(&xas, flags);
- while (i--) {
- int index = READ_ONCE(table[i].memcg->kmemcg_id);
- struct list_lru_memcg *mlru = table[i].mlru;
- xas_set(&xas, index);
- retry:
- if (unlikely(index < 0 || xas_error(&xas) || xas_load(&xas))) {
- kfree(mlru);
- } else {
- xas_store(&xas, mlru);
- if (xas_error(&xas) == -ENOMEM) {
- xas_unlock_irqrestore(&xas, flags);
- if (xas_nomem(&xas, gfp))
- xas_set_err(&xas, 0);
- xas_lock_irqsave(&xas, flags);
- /*
- * The xas lock has been released, this memcg
- * can be reparented before us. So reload
- * memcg id. More details see the comments
- * in memcg_reparent_list_lrus().
- */
- index = READ_ONCE(table[i].memcg->kmemcg_id);
- if (index < 0)
- xas_set_err(&xas, 0);
- else if (!xas_error(&xas) && index != xas.xa_index)
- xas_set(&xas, index);
- goto retry;
- }
- }
- }
- /* xas_nomem() is used to free memory instead of memory allocation. */
- if (xas.xa_alloc)
- xas_nomem(&xas, gfp);
- xas_unlock_irqrestore(&xas, flags);
- kfree(table);
- return xas_error(&xas);
- }
- #else
- static inline void memcg_init_list_lru(struct list_lru *lru, bool memcg_aware)
- {
- }
- static void memcg_destroy_list_lru(struct list_lru *lru)
- {
- }
- #endif /* CONFIG_MEMCG_KMEM */
- int __list_lru_init(struct list_lru *lru, bool memcg_aware,
- struct lock_class_key *key, struct shrinker *shrinker)
- {
- int i;
- #ifdef CONFIG_MEMCG_KMEM
- if (shrinker)
- lru->shrinker_id = shrinker->id;
- else
- lru->shrinker_id = -1;
- #endif
- lru->node = kcalloc(nr_node_ids, sizeof(*lru->node), GFP_KERNEL);
- if (!lru->node)
- return -ENOMEM;
- for_each_node(i) {
- spin_lock_init(&lru->node[i].lock);
- if (key)
- lockdep_set_class(&lru->node[i].lock, key);
- init_one_lru(&lru->node[i].lru);
- }
- memcg_init_list_lru(lru, memcg_aware);
- list_lru_register(lru);
- return 0;
- }
- EXPORT_SYMBOL_GPL(__list_lru_init);
- void list_lru_destroy(struct list_lru *lru)
- {
- /* Already destroyed or not yet initialized? */
- if (!lru->node)
- return;
- list_lru_unregister(lru);
- memcg_destroy_list_lru(lru);
- kfree(lru->node);
- lru->node = NULL;
- #ifdef CONFIG_MEMCG_KMEM
- lru->shrinker_id = -1;
- #endif
- }
- EXPORT_SYMBOL_GPL(list_lru_destroy);
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