// 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" #ifdef CONFIG_MEMCG_KMEM static LIST_HEAD(list_lrus); static DEFINE_MUTEX(list_lrus_mutex); static void list_lru_register(struct list_lru *lru) { mutex_lock(&list_lrus_mutex); list_add(&lru->list, &list_lrus); mutex_unlock(&list_lrus_mutex); } static void list_lru_unregister(struct list_lru *lru) { 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 bool list_lru_memcg_aware(struct list_lru *lru) { return lru->memcg_aware; } static inline struct list_lru_one * list_lru_from_memcg_idx(struct list_lru_node *nlru, int idx) { struct list_lru_memcg *memcg_lrus; /* * Either lock or RCU protects the array of per cgroup lists * from relocation (see memcg_update_list_lru_node). */ memcg_lrus = rcu_dereference_check(nlru->memcg_lrus, lockdep_is_held(&nlru->lock)); if (memcg_lrus && idx >= 0) return memcg_lrus->lru[idx]; return &nlru->lru; } static inline struct list_lru_one * list_lru_from_kmem(struct list_lru_node *nlru, void *ptr, struct mem_cgroup **memcg_ptr) { struct list_lru_one *l = &nlru->lru; struct mem_cgroup *memcg = NULL; if (!nlru->memcg_lrus) goto out; memcg = mem_cgroup_from_obj(ptr); if (!memcg) goto out; l = list_lru_from_memcg_idx(nlru, memcg_cache_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_node *nlru, int idx) { return &nlru->lru; } static inline struct list_lru_one * list_lru_from_kmem(struct list_lru_node *nlru, void *ptr, struct mem_cgroup **memcg_ptr) { if (memcg_ptr) *memcg_ptr = NULL; return &nlru->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(nlru, 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(nlru, 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_node *nlru = &lru->node[nid]; struct list_lru_one *l; unsigned long count; rcu_read_lock(); l = list_lru_from_memcg_idx(nlru, memcg_cache_id(memcg)); count = READ_ONCE(l->nr_items); rcu_read_unlock(); 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_node *nlru, int memcg_idx, list_lru_walk_cb isolate, void *cb_arg, unsigned long *nr_to_walk) { struct list_lru_one *l; struct list_head *item, *n; unsigned long isolated = 0; l = list_lru_from_memcg_idx(nlru, memcg_idx); restart: 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(); } } 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(nlru, memcg_cache_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(nlru, memcg_cache_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; int memcg_idx; isolated += list_lru_walk_one(lru, nid, NULL, isolate, cb_arg, nr_to_walk); if (*nr_to_walk > 0 && list_lru_memcg_aware(lru)) { for_each_memcg_cache_index(memcg_idx) { struct list_lru_node *nlru = &lru->node[nid]; spin_lock(&nlru->lock); isolated += __list_lru_walk_one(nlru, memcg_idx, isolate, cb_arg, nr_to_walk); spin_unlock(&nlru->lock); if (*nr_to_walk <= 0) break; } } 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 void __memcg_destroy_list_lru_node(struct list_lru_memcg *memcg_lrus, int begin, int end) { int i; for (i = begin; i < end; i++) kfree(memcg_lrus->lru[i]); } static int __memcg_init_list_lru_node(struct list_lru_memcg *memcg_lrus, int begin, int end) { int i; for (i = begin; i < end; i++) { struct list_lru_one *l; l = kmalloc(sizeof(struct list_lru_one), GFP_KERNEL); if (!l) goto fail; init_one_lru(l); memcg_lrus->lru[i] = l; } return 0; fail: __memcg_destroy_list_lru_node(memcg_lrus, begin, i); return -ENOMEM; } static int memcg_init_list_lru_node(struct list_lru_node *nlru) { struct list_lru_memcg *memcg_lrus; int size = memcg_nr_cache_ids; memcg_lrus = kvmalloc(sizeof(*memcg_lrus) + size * sizeof(void *), GFP_KERNEL); if (!memcg_lrus) return -ENOMEM; if (__memcg_init_list_lru_node(memcg_lrus, 0, size)) { kvfree(memcg_lrus); return -ENOMEM; } RCU_INIT_POINTER(nlru->memcg_lrus, memcg_lrus); return 0; } static void memcg_destroy_list_lru_node(struct list_lru_node *nlru) { struct list_lru_memcg *memcg_lrus; /* * This is called when shrinker has already been unregistered, * and nobody can use it. So, there is no need to use kvfree_rcu(). */ memcg_lrus = rcu_dereference_protected(nlru->memcg_lrus, true); __memcg_destroy_list_lru_node(memcg_lrus, 0, memcg_nr_cache_ids); kvfree(memcg_lrus); } static int memcg_update_list_lru_node(struct list_lru_node *nlru, int old_size, int new_size) { struct list_lru_memcg *old, *new; BUG_ON(old_size > new_size); old = rcu_dereference_protected(nlru->memcg_lrus, lockdep_is_held(&list_lrus_mutex)); new = kvmalloc(sizeof(*new) + new_size * sizeof(void *), GFP_KERNEL); if (!new) return -ENOMEM; if (__memcg_init_list_lru_node(new, old_size, new_size)) { kvfree(new); return -ENOMEM; } memcpy(&new->lru, &old->lru, old_size * sizeof(void *)); /* * The locking below allows readers that hold nlru->lock avoid taking * rcu_read_lock (see list_lru_from_memcg_idx). * * 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); rcu_assign_pointer(nlru->memcg_lrus, new); spin_unlock_irq(&nlru->lock); kvfree_rcu(old, rcu); return 0; } static void memcg_cancel_update_list_lru_node(struct list_lru_node *nlru, int old_size, int new_size) { struct list_lru_memcg *memcg_lrus; memcg_lrus = rcu_dereference_protected(nlru->memcg_lrus, lockdep_is_held(&list_lrus_mutex)); /* do not bother shrinking the array back to the old size, because we * cannot handle allocation failures here */ __memcg_destroy_list_lru_node(memcg_lrus, old_size, new_size); } static int memcg_init_list_lru(struct list_lru *lru, bool memcg_aware) { int i; lru->memcg_aware = memcg_aware; if (!memcg_aware) return 0; for_each_node(i) { if (memcg_init_list_lru_node(&lru->node[i])) goto fail; } return 0; fail: for (i = i - 1; i >= 0; i--) { if (!lru->node[i].memcg_lrus) continue; memcg_destroy_list_lru_node(&lru->node[i]); } return -ENOMEM; } static void memcg_destroy_list_lru(struct list_lru *lru) { int i; if (!list_lru_memcg_aware(lru)) return; for_each_node(i) memcg_destroy_list_lru_node(&lru->node[i]); } static int memcg_update_list_lru(struct list_lru *lru, int old_size, int new_size) { int i; if (!list_lru_memcg_aware(lru)) return 0; for_each_node(i) { if (memcg_update_list_lru_node(&lru->node[i], old_size, new_size)) goto fail; } return 0; fail: for (i = i - 1; i >= 0; i--) { if (!lru->node[i].memcg_lrus) continue; memcg_cancel_update_list_lru_node(&lru->node[i], old_size, new_size); } return -ENOMEM; } static void memcg_cancel_update_list_lru(struct list_lru *lru, int old_size, int new_size) { int i; if (!list_lru_memcg_aware(lru)) return; for_each_node(i) memcg_cancel_update_list_lru_node(&lru->node[i], old_size, new_size); } int memcg_update_all_list_lrus(int new_size) { int ret = 0; struct list_lru *lru; int old_size = memcg_nr_cache_ids; mutex_lock(&list_lrus_mutex); list_for_each_entry(lru, &list_lrus, list) { ret = memcg_update_list_lru(lru, old_size, new_size); if (ret) goto fail; } out: mutex_unlock(&list_lrus_mutex); return ret; fail: list_for_each_entry_continue_reverse(lru, &list_lrus, list) memcg_cancel_update_list_lru(lru, old_size, new_size); goto out; } static void memcg_drain_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(nlru, src_idx); dst = list_lru_from_memcg_idx(nlru, 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; } spin_unlock_irq(&nlru->lock); } static void memcg_drain_list_lru(struct list_lru *lru, int src_idx, struct mem_cgroup *dst_memcg) { int i; if (!list_lru_memcg_aware(lru)) return; for_each_node(i) memcg_drain_list_lru_node(lru, i, src_idx, dst_memcg); } void memcg_drain_all_list_lrus(int src_idx, struct mem_cgroup *dst_memcg) { struct list_lru *lru; mutex_lock(&list_lrus_mutex); list_for_each_entry(lru, &list_lrus, list) memcg_drain_list_lru(lru, src_idx, dst_memcg); mutex_unlock(&list_lrus_mutex); } #else static int memcg_init_list_lru(struct list_lru *lru, bool memcg_aware) { return 0; } 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; int err = -ENOMEM; #ifdef CONFIG_MEMCG_KMEM if (shrinker) lru->shrinker_id = shrinker->id; else lru->shrinker_id = -1; #endif memcg_get_cache_ids(); lru->node = kcalloc(nr_node_ids, sizeof(*lru->node), GFP_KERNEL); if (!lru->node) goto out; 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); } err = memcg_init_list_lru(lru, memcg_aware); if (err) { kfree(lru->node); /* Do this so a list_lru_destroy() doesn't crash: */ lru->node = NULL; goto out; } list_lru_register(lru); out: memcg_put_cache_ids(); return err; } EXPORT_SYMBOL_GPL(__list_lru_init); void list_lru_destroy(struct list_lru *lru) { /* Already destroyed or not yet initialized? */ if (!lru->node) return; memcg_get_cache_ids(); list_lru_unregister(lru); memcg_destroy_list_lru(lru); kfree(lru->node); lru->node = NULL; #ifdef CONFIG_MEMCG_KMEM lru->shrinker_id = -1; #endif memcg_put_cache_ids(); } EXPORT_SYMBOL_GPL(list_lru_destroy);