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_score_adj values will get killed. Specify
   5  * the minimum oom_score_adj values in
   6  * /sys/module/lowmemorykiller/parameters/adj and the number of free pages in
   7  * /sys/module/lowmemorykiller/parameters/minfree. Both files take a comma
   8  * separated list of numbers in ascending order.
   9  *
  10  * For example, write "0,8" to /sys/module/lowmemorykiller/parameters/adj and
  11  * "1024,4096" to /sys/module/lowmemorykiller/parameters/minfree to kill
  12  * processes with a oom_score_adj value of 8 or higher when the free memory
  13  * drops below 4096 pages and kill processes with a oom_score_adj value of 0 or
  14  * higher when the free memory drops below 1024 pages.
  15  *
  16  * The driver considers memory used for caches to be free, but if a large
  17  * percentage of the cached memory is locked this can be very inaccurate
  18  * and processes may not get killed until the normal oom killer is triggered.
  19  *
  20  * Copyright (C) 2007-2008 Google, Inc.
  21  *
  22  * This software is licensed under the terms of the GNU General Public
  23  * License version 2, as published by the Free Software Foundation, and
  24  * may be copied, distributed, and modified under those terms.
  25  *
  26  * This program is distributed in the hope that it will be useful,
  27  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  28  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  29  * GNU General Public License for more details.
  30  *
  31  */
  32
  33 #include <linux/module.h>
  34 #include <linux/kernel.h>
  35 #include <linux/mm.h>
  36 #include <linux/oom.h>
  37 #include <linux/sched.h>
  38 #include <linux/rcupdate.h>
  39 #include <linux/profile.h>
  40 #include <linux/notifier.h>
  41
  42 static uint32_t lowmem_debug_level = 2;
  43 static int lowmem_adj[6] = {
  44         0,
  45         1,
  46         6,
  47         12,
  48 };
  49 static int lowmem_adj_size = 4;
  50 static int lowmem_minfree[6] = {
  51         3 * 512,        /* 6MB */
  52         2 * 1024,       /* 8MB */
  53         4 * 1024,       /* 16MB */
  54         16 * 1024,      /* 64MB */
  55 };
  56 static int lowmem_minfree_size = 4;
  57
  58 static unsigned long lowmem_deathpending_timeout;
  59
  60 #define lowmem_print(level, x...)                       \
  61         do {                                            \
  62                 if (lowmem_debug_level >= (level))      \
  63                         printk(x);                      \
  64         } while (0)
  65
  66 static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
  67 {
  68         struct task_struct *tsk;
  69         struct task_struct *selected = NULL;
  70         int rem = 0;
  71         int tasksize;
  72         int i;
  73         int min_score_adj = OOM_SCORE_ADJ_MAX + 1;
  74         int selected_tasksize = 0;
  75         int selected_oom_score_adj;
  76         int array_size = ARRAY_SIZE(lowmem_adj);
  77         int other_free = global_page_state(NR_FREE_PAGES);
  78         int other_file = global_page_state(NR_FILE_PAGES) -
  79                                                 global_page_state(NR_SHMEM);
  80
  81         if (lowmem_adj_size < array_size)
  82                 array_size = lowmem_adj_size;
  83         if (lowmem_minfree_size < array_size)
  84                 array_size = lowmem_minfree_size;
  85         for (i = 0; i < array_size; i++) {
  86                 if (other_free < lowmem_minfree[i] &&
  87                     other_file < lowmem_minfree[i]) {
  88                         min_score_adj = lowmem_adj[i];
  89                         break;
  90                 }
  91         }
  92         if (sc->nr_to_scan > 0)
  93                 lowmem_print(3, "lowmem_shrink %lu, %x, ofree %d %d, ma %d\n",
  94                                 sc->nr_to_scan, sc->gfp_mask, other_free,
  95                                 other_file, min_score_adj);
  96         rem = global_page_state(NR_ACTIVE_ANON) +
  97                 global_page_state(NR_ACTIVE_FILE) +
  98                 global_page_state(NR_INACTIVE_ANON) +
  99                 global_page_state(NR_INACTIVE_FILE);
 100         if (sc->nr_to_scan <= 0 || min_score_adj == OOM_SCORE_ADJ_MAX + 1) {
 101                 lowmem_print(5, "lowmem_shrink %lu, %x, return %d\n",
 102                              sc->nr_to_scan, sc->gfp_mask, rem);
 103                 return rem;
 104         }
 105         selected_oom_score_adj = min_score_adj;
 106
 107         rcu_read_lock();
 108         for_each_process(tsk) {
 109                 struct task_struct *p;
 110                 int oom_score_adj;
 111
 112                 if (tsk->flags & PF_KTHREAD)
 113                         continue;
 114
 115                 p = find_lock_task_mm(tsk);
 116                 if (!p)
 117                         continue;
 118
 119                 if (test_tsk_thread_flag(p, TIF_MEMDIE) &&
 120                     time_before_eq(jiffies, lowmem_deathpending_timeout)) {
 121                         task_unlock(p);
 122                         rcu_read_unlock();
 123                         return 0;
 124                 }
 125                 oom_score_adj = p->signal->oom_score_adj;
 126                 if (oom_score_adj < min_score_adj) {
 127                         task_unlock(p);
 128                         continue;
 129                 }
 130                 tasksize = get_mm_rss(p->mm);
 131                 task_unlock(p);
 132                 if (tasksize <= 0)
 133                         continue;
 134                 if (selected) {
 135                         if (oom_score_adj < selected_oom_score_adj)
 136                                 continue;
 137                         if (oom_score_adj == selected_oom_score_adj &&
 138                             tasksize <= selected_tasksize)
 139                                 continue;
 140                 }
 141                 selected = p;
 142                 selected_tasksize = tasksize;
 143                 selected_oom_score_adj = oom_score_adj;
 144                 lowmem_print(2, "select %d (%s), adj %d, size %d, to kill\n",
 145                              p->pid, p->comm, oom_score_adj, tasksize);
 146         }
 147         if (selected) {
 148                 lowmem_print(1, "send sigkill to %d (%s), adj %d, size %d\n",
 149                              selected->pid, selected->comm,
 150                              selected_oom_score_adj, selected_tasksize);
 151                 lowmem_deathpending_timeout = jiffies + HZ;
 152                 send_sig(SIGKILL, selected, 0);
 153                 set_tsk_thread_flag(selected, TIF_MEMDIE);
 154                 rem -= selected_tasksize;
 155         }
 156         lowmem_print(4, "lowmem_shrink %lu, %x, return %d\n",
 157                      sc->nr_to_scan, sc->gfp_mask, rem);
 158         rcu_read_unlock();
 159         return rem;
 160 }
 161
 162 static struct shrinker lowmem_shrinker = {
 163         .shrink = lowmem_shrink,
 164         .seeks = DEFAULT_SEEKS * 16
 165 };
 166
 167 static int __init lowmem_init(void)
 168 {
 169         register_shrinker(&lowmem_shrinker);
 170         return 0;
 171 }
 172
 173 static void __exit lowmem_exit(void)
 174 {
 175         unregister_shrinker(&lowmem_shrinker);
 176 }
 177
 178 module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR);
 179 module_param_array_named(adj, lowmem_adj, int, &lowmem_adj_size,
 180                          S_IRUGO | S_IWUSR);
 181 module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
 182                          S_IRUGO | S_IWUSR);
 183 module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR);
 184
 185 module_init(lowmem_init);
 186 module_exit(lowmem_exit);
 187
 188 MODULE_LICENSE("GPL");
 189