mm/list_lru.c

   1 /*
   2  * Copyright (c) 2013 Red Hat, Inc. and Parallels Inc. All rights reserved.
   3  * Authors: David Chinner and Glauber Costa
   4  *
   5  * Generic LRU infrastructure
   6  */
   7 #include <linux/kernel.h>
   8 #include <linux/module.h>
   9 #include <linux/mm.h>
  10 #include <linux/list_lru.h>
  11 #include <linux/slab.h>
  12
  13 bool list_lru_add(struct list_lru *lru, struct list_head *item)
  14 {
  15         int nid = page_to_nid(virt_to_page(item));
  16         struct list_lru_node *nlru = &lru->node[nid];
  17
  18         spin_lock(&nlru->lock);
  19         WARN_ON_ONCE(nlru->nr_items < 0);
  20         if (list_empty(item)) {
  21                 list_add_tail(item, &nlru->list);
  22                 if (nlru->nr_items++ == 0)
  23                         node_set(nid, lru->active_nodes);
  24                 spin_unlock(&nlru->lock);
  25                 return true;
  26         }
  27         spin_unlock(&nlru->lock);
  28         return false;
  29 }
  30 EXPORT_SYMBOL_GPL(list_lru_add);
  31
  32 bool list_lru_del(struct list_lru *lru, struct list_head *item)
  33 {
  34         int nid = page_to_nid(virt_to_page(item));
  35         struct list_lru_node *nlru = &lru->node[nid];
  36
  37         spin_lock(&nlru->lock);
  38         if (!list_empty(item)) {
  39                 list_del_init(item);
  40                 if (--nlru->nr_items == 0)
  41                         node_clear(nid, lru->active_nodes);
  42                 WARN_ON_ONCE(nlru->nr_items < 0);
  43                 spin_unlock(&nlru->lock);
  44                 return true;
  45         }
  46         spin_unlock(&nlru->lock);
  47         return false;
  48 }
  49 EXPORT_SYMBOL_GPL(list_lru_del);
  50
  51 unsigned long
  52 list_lru_count_node(struct list_lru *lru, int nid)
  53 {
  54         unsigned long count = 0;
  55         struct list_lru_node *nlru = &lru->node[nid];
  56
  57         spin_lock(&nlru->lock);
  58         WARN_ON_ONCE(nlru->nr_items < 0);
  59         count += nlru->nr_items;
  60         spin_unlock(&nlru->lock);
  61
  62         return count;
  63 }
  64 EXPORT_SYMBOL_GPL(list_lru_count_node);
  65
  66 unsigned long
  67 list_lru_walk_node(struct list_lru *lru, int nid, list_lru_walk_cb isolate,
  68                    void *cb_arg, unsigned long *nr_to_walk)
  69 {
  70
  71         struct list_lru_node    *nlru = &lru->node[nid];
  72         struct list_head *item, *n;
  73         unsigned long isolated = 0;
  74
  75         spin_lock(&nlru->lock);
  76 restart:
  77         list_for_each_safe(item, n, &nlru->list) {
  78                 enum lru_status ret;
  79
  80                 /*
  81                  * decrement nr_to_walk first so that we don't livelock if we
  82                  * get stuck on large numbesr of LRU_RETRY items
  83                  */
  84                 if (--(*nr_to_walk) == 0)
  85                         break;
  86
  87                 ret = isolate(item, &nlru->lock, cb_arg);
  88                 switch (ret) {
  89                 case LRU_REMOVED:
  90                         if (--nlru->nr_items == 0)
  91                                 node_clear(nid, lru->active_nodes);
  92                         WARN_ON_ONCE(nlru->nr_items < 0);
  93                         isolated++;
  94                         break;
  95                 case LRU_ROTATE:
  96                         list_move_tail(item, &nlru->list);
  97                         break;
  98                 case LRU_SKIP:
  99                         break;
 100                 case LRU_RETRY:
 101                         /*
 102                          * The lru lock has been dropped, our list traversal is
 103                          * now invalid and so we have to restart from scratch.
 104                          */
 105                         goto restart;
 106                 default:
 107                         BUG();
 108                 }
 109         }
 110
 111         spin_unlock(&nlru->lock);
 112         return isolated;
 113 }
 114 EXPORT_SYMBOL_GPL(list_lru_walk_node);
 115
 116 int list_lru_init(struct list_lru *lru)
 117 {
 118         int i;
 119         size_t size = sizeof(*lru->node) * nr_node_ids;
 120
 121         lru->node = kzalloc(size, GFP_KERNEL);
 122         if (!lru->node)
 123                 return -ENOMEM;
 124
 125         nodes_clear(lru->active_nodes);
 126         for (i = 0; i < nr_node_ids; i++) {
 127                 spin_lock_init(&lru->node[i].lock);
 128                 INIT_LIST_HEAD(&lru->node[i].list);
 129                 lru->node[i].nr_items = 0;
 130         }
 131         return 0;
 132 }
 133 EXPORT_SYMBOL_GPL(list_lru_init);
 134
 135 void list_lru_destroy(struct list_lru *lru)
 136 {
 137         kfree(lru->node);
 138 }
 139 EXPORT_SYMBOL_GPL(list_lru_destroy);