kernel

linux-6.8.1/include/linux/list_lru.h

@@ -0,0 +1,271 @@
+/* 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 */