include/linux/list_lru.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Copyright (c) 2013 Red Hat, Inc. and Parallels Inc. All rights reserved.
   4  * Authors: David Chinner and Glauber Costa
   5  *
   6  * Generic LRU infrastructure
   7  */
   8 #ifndef _LRU_LIST_H
   9 #define _LRU_LIST_H
  10
  11 #include <linux/list.h>
  12 #include <linux/nodemask.h>
  13 #include <linux/shrinker.h>
  14 #include <linux/xarray.h>
  15
  16 struct mem_cgroup;
  17
  18 /* list_lru_walk_cb has to always return one of those */
  19 enum lru_status {
  20         LRU_REMOVED,            /* item removed from list */
  21         LRU_REMOVED_RETRY,      /* item removed, but lock has been
  22                                    dropped and reacquired */
  23         LRU_ROTATE,             /* item referenced, give another pass */
  24         LRU_SKIP,               /* item cannot be locked, skip */
  25         LRU_RETRY,              /* item not freeable. May drop the lock
  26                                    internally, but has to return locked. */
  27         LRU_STOP,               /* stop lru list walking. May drop the lock
  28                                    internally, but has to return locked. */
  29 };
  30
  31 struct list_lru_one {
  32         struct list_head        list;
  33         /* may become negative during memcg reparenting */
  34         long                    nr_items;
  35         /* protects all fields above */
  36         spinlock_t              lock;
  37 };
  38
  39 struct list_lru_memcg {
  40         struct rcu_head         rcu;
  41         /* array of per cgroup per node lists, indexed by node id */
  42         struct list_lru_one     node[];
  43 };
  44
  45 struct list_lru_node {
  46         /* global list, used for the root cgroup in cgroup aware lrus */
  47         struct list_lru_one     lru;
  48         atomic_long_t           nr_items;
  49 } ____cacheline_aligned_in_smp;
  50
  51 struct list_lru {
  52         struct list_lru_node    *node;
  53 #ifdef CONFIG_MEMCG
  54         struct list_head        list;
  55         int                     shrinker_id;
  56         bool                    memcg_aware;
  57         struct xarray           xa;
  58 #endif
  59 #ifdef CONFIG_LOCKDEP
  60         struct lock_class_key   *key;
  61 #endif
  62 };
  63
  64 void list_lru_destroy(struct list_lru *lru);
  65 int __list_lru_init(struct list_lru *lru, bool memcg_aware,
  66                     struct shrinker *shrinker);
  67
  68 #define list_lru_init(lru)                              \
  69         __list_lru_init((lru), false, NULL)
  70 #define list_lru_init_memcg(lru, shrinker)              \
  71         __list_lru_init((lru), true, shrinker)
  72
  73 static inline int list_lru_init_memcg_key(struct list_lru *lru, struct shrinker *shrinker,
  74                                           struct lock_class_key *key)
  75 {
  76 #ifdef CONFIG_LOCKDEP
  77         lru->key = key;
  78 #endif
  79         return list_lru_init_memcg(lru, shrinker);
  80 }
  81
  82 int memcg_list_lru_alloc(struct mem_cgroup *memcg, struct list_lru *lru,
  83                          gfp_t gfp);
  84 void memcg_reparent_list_lrus(struct mem_cgroup *memcg, struct mem_cgroup *parent);
  85
  86 /**
  87  * list_lru_add: add an element to the lru list's tail
  88  * @lru: the lru pointer
  89  * @item: the item to be added.
  90  * @nid: the node id of the sublist to add the item to.
  91  * @memcg: the cgroup of the sublist to add the item to.
  92  *
  93  * If the element is already part of a list, this function returns doing
  94  * nothing. Therefore the caller does not need to keep state about whether or
  95  * not the element already belongs in the list and is allowed to lazy update
  96  * it. Note however that this is valid for *a* list, not *this* list. If
  97  * the caller organize itself in a way that elements can be in more than
  98  * one type of list, it is up to the caller to fully remove the item from
  99  * the previous list (with list_lru_del() for instance) before moving it
 100  * to @lru.
 101  *
 102  * Return: true if the list was updated, false otherwise
 103  */
 104 bool list_lru_add(struct list_lru *lru, struct list_head *item, int nid,
 105                     struct mem_cgroup *memcg);
 106
 107 /**
 108  * list_lru_add_obj: add an element to the lru list's tail
 109  * @lru: the lru pointer
 110  * @item: the item to be added.
 111  *
 112  * This function is similar to list_lru_add(), but the NUMA node and the
 113  * memcg of the sublist is determined by @item list_head. This assumption is
 114  * valid for slab objects LRU such as dentries, inodes, etc.
 115  *
 116  * Return value: true if the list was updated, false otherwise
 117  */
 118 bool list_lru_add_obj(struct list_lru *lru, struct list_head *item);
 119
 120 /**
 121  * list_lru_del: delete an element from the lru list
 122  * @lru: the lru pointer
 123  * @item: the item to be deleted.
 124  * @nid: the node id of the sublist to delete the item from.
 125  * @memcg: the cgroup of the sublist to delete the item from.
 126  *
 127  * This function works analogously as list_lru_add() in terms of list
 128  * manipulation. The comments about an element already pertaining to
 129  * a list are also valid for list_lru_del().
 130  *
 131  * Return: true if the list was updated, false otherwise
 132  */
 133 bool list_lru_del(struct list_lru *lru, struct list_head *item, int nid,
 134                     struct mem_cgroup *memcg);
 135
 136 /**
 137  * list_lru_del_obj: delete an element from the lru list
 138  * @lru: the lru pointer
 139  * @item: the item to be deleted.
 140  *
 141  * This function is similar to list_lru_del(), but the NUMA node and the
 142  * memcg of the sublist is determined by @item list_head. This assumption is
 143  * valid for slab objects LRU such as dentries, inodes, etc.
 144  *
 145  * Return value: true if the list was updated, false otherwise.
 146  */
 147 bool list_lru_del_obj(struct list_lru *lru, struct list_head *item);
 148
 149 /**
 150  * list_lru_count_one: return the number of objects currently held by @lru
 151  * @lru: the lru pointer.
 152  * @nid: the node id to count from.
 153  * @memcg: the cgroup to count from.
 154  *
 155  * There is no guarantee that the list is not updated while the count is being
 156  * computed. Callers that want such a guarantee need to provide an outer lock.
 157  *
 158  * Return: 0 for empty lists, otherwise the number of objects
 159  * currently held by @lru.
 160  */
 161 unsigned long list_lru_count_one(struct list_lru *lru,
 162                                  int nid, struct mem_cgroup *memcg);
 163 unsigned long list_lru_count_node(struct list_lru *lru, int nid);
 164
 165 static inline unsigned long list_lru_shrink_count(struct list_lru *lru,
 166                                                   struct shrink_control *sc)
 167 {
 168         return list_lru_count_one(lru, sc->nid, sc->memcg);
 169 }
 170
 171 static inline unsigned long list_lru_count(struct list_lru *lru)
 172 {
 173         long count = 0;
 174         int nid;
 175
 176         for_each_node_state(nid, N_NORMAL_MEMORY)
 177                 count += list_lru_count_node(lru, nid);
 178
 179         return count;
 180 }
 181
 182 void list_lru_isolate(struct list_lru_one *list, struct list_head *item);
 183 void list_lru_isolate_move(struct list_lru_one *list, struct list_head *item,
 184                            struct list_head *head);
 185
 186 typedef enum lru_status (*list_lru_walk_cb)(struct list_head *item,
 187                 struct list_lru_one *list, void *cb_arg);
 188
 189 /**
 190  * list_lru_walk_one: walk a @lru, isolating and disposing freeable items.
 191  * @lru: the lru pointer.
 192  * @nid: the node id to scan from.
 193  * @memcg: the cgroup to scan from.
 194  * @isolate: callback function that is responsible for deciding what to do with
 195  *  the item currently being scanned
 196  * @cb_arg: opaque type that will be passed to @isolate
 197  * @nr_to_walk: how many items to scan.
 198  *
 199  * This function will scan all elements in a particular @lru, calling the
 200  * @isolate callback for each of those items, along with the current list
 201  * spinlock and a caller-provided opaque. The @isolate callback can choose to
 202  * drop the lock internally, but *must* return with the lock held. The callback
 203  * will return an enum lru_status telling the @lru infrastructure what to
 204  * do with the object being scanned.
 205  *
 206  * Please note that @nr_to_walk does not mean how many objects will be freed,
 207  * just how many objects will be scanned.
 208  *
 209  * Return: the number of objects effectively removed from the LRU.
 210  */
 211 unsigned long list_lru_walk_one(struct list_lru *lru,
 212                                 int nid, struct mem_cgroup *memcg,
 213                                 list_lru_walk_cb isolate, void *cb_arg,
 214                                 unsigned long *nr_to_walk);
 215 /**
 216  * list_lru_walk_one_irq: walk a @lru, isolating and disposing freeable items.
 217  * @lru: the lru pointer.
 218  * @nid: the node id to scan from.
 219  * @memcg: the cgroup to scan from.
 220  * @isolate: callback function that is responsible for deciding what to do with
 221  *  the item currently being scanned
 222  * @cb_arg: opaque type that will be passed to @isolate
 223  * @nr_to_walk: how many items to scan.
 224  *
 225  * Same as list_lru_walk_one() except that the spinlock is acquired with
 226  * spin_lock_irq().
 227  */
 228 unsigned long list_lru_walk_one_irq(struct list_lru *lru,
 229                                     int nid, struct mem_cgroup *memcg,
 230                                     list_lru_walk_cb isolate, void *cb_arg,
 231                                     unsigned long *nr_to_walk);
 232 unsigned long list_lru_walk_node(struct list_lru *lru, int nid,
 233                                  list_lru_walk_cb isolate, void *cb_arg,
 234                                  unsigned long *nr_to_walk);
 235
 236 static inline unsigned long
 237 list_lru_shrink_walk(struct list_lru *lru, struct shrink_control *sc,
 238                      list_lru_walk_cb isolate, void *cb_arg)
 239 {
 240         return list_lru_walk_one(lru, sc->nid, sc->memcg, isolate, cb_arg,
 241                                  &sc->nr_to_scan);
 242 }
 243
 244 static inline unsigned long
 245 list_lru_shrink_walk_irq(struct list_lru *lru, struct shrink_control *sc,
 246                          list_lru_walk_cb isolate, void *cb_arg)
 247 {
 248         return list_lru_walk_one_irq(lru, sc->nid, sc->memcg, isolate, cb_arg,
 249                                      &sc->nr_to_scan);
 250 }
 251
 252 static inline unsigned long
 253 list_lru_walk(struct list_lru *lru, list_lru_walk_cb isolate,
 254               void *cb_arg, unsigned long nr_to_walk)
 255 {
 256         long isolated = 0;
 257         int nid;
 258
 259         for_each_node_state(nid, N_NORMAL_MEMORY) {
 260                 isolated += list_lru_walk_node(lru, nid, isolate,
 261                                                cb_arg, &nr_to_walk);
 262                 if (nr_to_walk <= 0)
 263                         break;
 264         }
 265         return isolated;
 266 }
 267 #endif /* _LRU_LIST_H */