// 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);