drivers/staging/android/lowmemorykiller.c

   1 /* drivers/misc/lowmemorykiller.c
   2  *
   3  * Copyright (C) 2007-2008 Google, Inc.
   4  *
   5  * This software is licensed under the terms of the GNU General Public
   6  * License version 2, as published by the Free Software Foundation, and
   7  * may be copied, distributed, and modified under those terms.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  */
  15
  16 #include <linux/module.h>
  17 #include <linux/kernel.h>
  18 #include <linux/mm.h>
  19 #include <linux/oom.h>
  20 #include <linux/sched.h>
  21
  22 static int lowmem_shrink(int nr_to_scan, gfp_t gfp_mask);
  23
  24 static struct shrinker lowmem_shrinker = {
  25         .shrink = lowmem_shrink,
  26         .seeks = DEFAULT_SEEKS * 16
  27 };
  28 static uint32_t lowmem_debug_level = 2;
  29 static int lowmem_adj[6] = {
  30         0,
  31         1,
  32         6,
  33         12,
  34 };
  35 static int lowmem_adj_size = 4;
  36 static size_t lowmem_minfree[6] = {
  37         3 * 512,        /* 6MB */
  38         2 * 1024,       /* 8MB */
  39         4 * 1024,       /* 16MB */
  40         16 * 1024,      /* 64MB */
  41 };
  42 static int lowmem_minfree_size = 4;
  43
  44 #define lowmem_print(level, x...)                       \
  45         do {                                            \
  46                 if (lowmem_debug_level >= (level))      \
  47                         printk(x);                      \
  48         } while (0)
  49
  50 module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR);
  51 module_param_array_named(adj, lowmem_adj, int, &lowmem_adj_size,
  52                          S_IRUGO | S_IWUSR);
  53 module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
  54                          S_IRUGO | S_IWUSR);
  55 module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR);
  56
  57 static int lowmem_shrink(int nr_to_scan, gfp_t gfp_mask)
  58 {
  59         struct task_struct *p;
  60         struct task_struct *selected = NULL;
  61         int rem = 0;
  62         int tasksize;
  63         int i;
  64         int min_adj = OOM_ADJUST_MAX + 1;
  65         int selected_tasksize = 0;
  66         int selected_oom_adj;
  67         int array_size = ARRAY_SIZE(lowmem_adj);
  68         int other_free = global_page_state(NR_FREE_PAGES);
  69         int other_file = global_page_state(NR_FILE_PAGES);
  70
  71         if (lowmem_adj_size < array_size)
  72                 array_size = lowmem_adj_size;
  73         if (lowmem_minfree_size < array_size)
  74                 array_size = lowmem_minfree_size;
  75         for (i = 0; i < array_size; i++) {
  76                 if (other_free < lowmem_minfree[i] &&
  77                     other_file < lowmem_minfree[i]) {
  78                         min_adj = lowmem_adj[i];
  79                         break;
  80                 }
  81         }
  82         if (nr_to_scan > 0)
  83                 lowmem_print(3, "lowmem_shrink %d, %x, ofree %d %d, ma %d\n",
  84                              nr_to_scan, gfp_mask, other_free, other_file,
  85                              min_adj);
  86         rem = global_page_state(NR_ACTIVE_ANON) +
  87                 global_page_state(NR_ACTIVE_FILE) +
  88                 global_page_state(NR_INACTIVE_ANON) +
  89                 global_page_state(NR_INACTIVE_FILE);
  90         if (nr_to_scan <= 0 || min_adj == OOM_ADJUST_MAX + 1) {
  91                 lowmem_print(5, "lowmem_shrink %d, %x, return %d\n",
  92                              nr_to_scan, gfp_mask, rem);
  93                 return rem;
  94         }
  95         selected_oom_adj = min_adj;
  96
  97         read_lock(&tasklist_lock);
  98         for_each_process(p) {
  99                 struct mm_struct *mm;
 100                 int oom_adj;
 101
 102                 task_lock(p);
 103                 mm = p->mm;
 104                 if (!mm) {
 105                         task_unlock(p);
 106                         continue;
 107                 }
 108                 oom_adj = mm->oom_adj;
 109                 if (oom_adj < min_adj) {
 110                         task_unlock(p);
 111                         continue;
 112                 }
 113                 tasksize = get_mm_rss(mm);
 114                 task_unlock(p);
 115                 if (tasksize <= 0)
 116                         continue;
 117                 if (selected) {
 118                         if (oom_adj < selected_oom_adj)
 119                                 continue;
 120                         if (oom_adj == selected_oom_adj &&
 121                             tasksize <= selected_tasksize)
 122                                 continue;
 123                 }
 124                 selected = p;
 125                 selected_tasksize = tasksize;
 126                 selected_oom_adj = oom_adj;
 127                 lowmem_print(2, "select %d (%s), adj %d, size %d, to kill\n",
 128                              p->pid, p->comm, oom_adj, tasksize);
 129         }
 130         if (selected) {
 131                 lowmem_print(1, "send sigkill to %d (%s), adj %d, size %d\n",
 132                              selected->pid, selected->comm,
 133                              selected_oom_adj, selected_tasksize);
 134                 force_sig(SIGKILL, selected);
 135                 rem -= selected_tasksize;
 136         }
 137         lowmem_print(4, "lowmem_shrink %d, %x, return %d\n",
 138                      nr_to_scan, gfp_mask, rem);
 139         read_unlock(&tasklist_lock);
 140         return rem;
 141 }
 142
 143 static int __init lowmem_init(void)
 144 {
 145         register_shrinker(&lowmem_shrinker);
 146         return 0;
 147 }
 148
 149 static void __exit lowmem_exit(void)
 150 {
 151         unregister_shrinker(&lowmem_shrinker);
 152 }
 153
 154 module_init(lowmem_init);
 155 module_exit(lowmem_exit);
 156
 157 MODULE_LICENSE("GPL");
 158