drivers/staging/android/lowmemorykiller.c

   1 /* drivers/misc/lowmemorykiller.c
   2  *
   3  * The lowmemorykiller driver lets user-space specify a set of memory thresholds
   4  * where processes with a range of oom_adj values will get killed. Specify the
   5  * minimum oom_adj values in /sys/module/lowmemorykiller/parameters/adj and the
   6  * number of free pages in /sys/module/lowmemorykiller/parameters/minfree. Both
   7  * files take a comma separated list of numbers in ascending order.
   8  *
   9  * For example, write "0,8" to /sys/module/lowmemorykiller/parameters/adj and
  10  * "1024,4096" to /sys/module/lowmemorykiller/parameters/minfree to kill processes
  11  * with a oom_adj value of 8 or higher when the free memory drops below 4096 pages
  12  * and kill processes with a oom_adj value of 0 or higher when the free memory
  13  * drops below 1024 pages.
  14  *
  15  * The driver considers memory used for caches to be free, but if a large
  16  * percentage of the cached memory is locked this can be very inaccurate
  17  * and processes may not get killed until the normal oom killer is triggered.
  18  *
  19  * Copyright (C) 2007-2008 Google, Inc.
  20  *
  21  * This software is licensed under the terms of the GNU General Public
  22  * License version 2, as published by the Free Software Foundation, and
  23  * may be copied, distributed, and modified under those terms.
  24  *
  25  * This program is distributed in the hope that it will be useful,
  26  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  27  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  28  * GNU General Public License for more details.
  29  *
  30  */
  31
  32 #include <linux/module.h>
  33 #include <linux/kernel.h>
  34 #include <linux/mm.h>
  35 #include <linux/oom.h>
  36 #include <linux/sched.h>
  37
  38 static uint32_t lowmem_debug_level = 2;
  39 static int lowmem_adj[6] = {
  40         0,
  41         1,
  42         6,
  43         12,
  44 };
  45 static int lowmem_adj_size = 4;
  46 static size_t lowmem_minfree[6] = {
  47         3 * 512,        /* 6MB */
  48         2 * 1024,       /* 8MB */
  49         4 * 1024,       /* 16MB */
  50         16 * 1024,      /* 64MB */
  51 };
  52 static int lowmem_minfree_size = 4;
  53
  54 #define lowmem_print(level, x...)                       \
  55         do {                                            \
  56                 if (lowmem_debug_level >= (level))      \
  57                         printk(x);                      \
  58         } while (0)
  59
  60 static int lowmem_shrink(int nr_to_scan, gfp_t gfp_mask)
  61 {
  62         struct task_struct *p;
  63         struct task_struct *selected = NULL;
  64         int rem = 0;
  65         int tasksize;
  66         int i;
  67         int min_adj = OOM_ADJUST_MAX + 1;
  68         int selected_tasksize = 0;
  69         int selected_oom_adj;
  70         int array_size = ARRAY_SIZE(lowmem_adj);
  71         int other_free = global_page_state(NR_FREE_PAGES);
  72         int other_file = global_page_state(NR_FILE_PAGES);
  73
  74         if (lowmem_adj_size < array_size)
  75                 array_size = lowmem_adj_size;
  76         if (lowmem_minfree_size < array_size)
  77                 array_size = lowmem_minfree_size;
  78         for (i = 0; i < array_size; i++) {
  79                 if (other_free < lowmem_minfree[i] &&
  80                     other_file < lowmem_minfree[i]) {
  81                         min_adj = lowmem_adj[i];
  82                         break;
  83                 }
  84         }
  85         if (nr_to_scan > 0)
  86                 lowmem_print(3, "lowmem_shrink %d, %x, ofree %d %d, ma %d\n",
  87                              nr_to_scan, gfp_mask, other_free, other_file,
  88                              min_adj);
  89         rem = global_page_state(NR_ACTIVE_ANON) +
  90                 global_page_state(NR_ACTIVE_FILE) +
  91                 global_page_state(NR_INACTIVE_ANON) +
  92                 global_page_state(NR_INACTIVE_FILE);
  93         if (nr_to_scan <= 0 || min_adj == OOM_ADJUST_MAX + 1) {
  94                 lowmem_print(5, "lowmem_shrink %d, %x, return %d\n",
  95                              nr_to_scan, gfp_mask, rem);
  96                 return rem;
  97         }
  98         selected_oom_adj = min_adj;
  99
 100         read_lock(&tasklist_lock);
 101         for_each_process(p) {
 102                 struct mm_struct *mm;
 103                 int oom_adj;
 104
 105                 task_lock(p);
 106                 mm = p->mm;
 107                 if (!mm) {
 108                         task_unlock(p);
 109                         continue;
 110                 }
 111                 oom_adj = mm->oom_adj;
 112                 if (oom_adj < min_adj) {
 113                         task_unlock(p);
 114                         continue;
 115                 }
 116                 tasksize = get_mm_rss(mm);
 117                 task_unlock(p);
 118                 if (tasksize <= 0)
 119                         continue;
 120                 if (selected) {
 121                         if (oom_adj < selected_oom_adj)
 122                                 continue;
 123                         if (oom_adj == selected_oom_adj &&
 124                             tasksize <= selected_tasksize)
 125                                 continue;
 126                 }
 127                 selected = p;
 128                 selected_tasksize = tasksize;
 129                 selected_oom_adj = oom_adj;
 130                 lowmem_print(2, "select %d (%s), adj %d, size %d, to kill\n",
 131                              p->pid, p->comm, oom_adj, tasksize);
 132         }
 133         if (selected) {
 134                 lowmem_print(1, "send sigkill to %d (%s), adj %d, size %d\n",
 135                              selected->pid, selected->comm,
 136                              selected_oom_adj, selected_tasksize);
 137                 force_sig(SIGKILL, selected);
 138                 rem -= selected_tasksize;
 139         }
 140         lowmem_print(4, "lowmem_shrink %d, %x, return %d\n",
 141                      nr_to_scan, gfp_mask, rem);
 142         read_unlock(&tasklist_lock);
 143         return rem;
 144 }
 145
 146 static struct shrinker lowmem_shrinker = {
 147         .shrink = lowmem_shrink,
 148         .seeks = DEFAULT_SEEKS * 16
 149 };
 150
 151 static int __init lowmem_init(void)
 152 {
 153         register_shrinker(&lowmem_shrinker);
 154         return 0;
 155 }
 156
 157 static void __exit lowmem_exit(void)
 158 {
 159         unregister_shrinker(&lowmem_shrinker);
 160 }
 161
 162 module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR);
 163 module_param_array_named(adj, lowmem_adj, int, &lowmem_adj_size,
 164                          S_IRUGO | S_IWUSR);
 165 module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
 166                          S_IRUGO | S_IWUSR);
 167 module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR);
 168
 169 module_init(lowmem_init);
 170 module_exit(lowmem_exit);
 171
 172 MODULE_LICENSE("GPL");
 173