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
  11  * processes with a oom_adj value of 8 or higher when the free memory drops
  12  * below 4096 pages and kill processes with a oom_adj value of 0 or higher
  13  * when the free memory 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 #include <linux/profile.h>
  38 #include <linux/notifier.h>
  39
  40 static uint32_t lowmem_debug_level = 2;
  41 static int lowmem_adj[6] = {
  42         0,
  43         1,
  44         6,
  45         12,
  46 };
  47 static int lowmem_adj_size = 4;
  48 static size_t lowmem_minfree[6] = {
  49         3 * 512,        /* 6MB */
  50         2 * 1024,       /* 8MB */
  51         4 * 1024,       /* 16MB */
  52         16 * 1024,      /* 64MB */
  53 };
  54 static int lowmem_minfree_size = 4;
  55
  56 static unsigned long lowmem_deathpending_timeout;
  57
  58 #define lowmem_print(level, x...)                       \
  59         do {                                            \
  60                 if (lowmem_debug_level >= (level))      \
  61                         printk(x);                      \
  62         } while (0)
  63
  64 static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
  65 {
  66         struct task_struct *p;
  67         struct task_struct *selected = NULL;
  68         int rem = 0;
  69         int tasksize;
  70         int i;
  71         int min_adj = OOM_ADJUST_MAX + 1;
  72         int selected_tasksize = 0;
  73         int selected_oom_adj;
  74         int array_size = ARRAY_SIZE(lowmem_adj);
  75         int other_free = global_page_state(NR_FREE_PAGES);
  76         int other_file = global_page_state(NR_FILE_PAGES) -
  77                                                 global_page_state(NR_SHMEM);
  78
  79         if (lowmem_adj_size < array_size)
  80                 array_size = lowmem_adj_size;
  81         if (lowmem_minfree_size < array_size)
  82                 array_size = lowmem_minfree_size;
  83         for (i = 0; i < array_size; i++) {
  84                 if (other_free < lowmem_minfree[i] &&
  85                     other_file < lowmem_minfree[i]) {
  86                         min_adj = lowmem_adj[i];
  87                         break;
  88                 }
  89         }
  90         if (sc->nr_to_scan > 0)
  91                 lowmem_print(3, "lowmem_shrink %lu, %x, ofree %d %d, ma %d\n",
  92                                 sc->nr_to_scan, sc->gfp_mask, other_free,
  93                                 other_file, min_adj);
  94         rem = global_page_state(NR_ACTIVE_ANON) +
  95                 global_page_state(NR_ACTIVE_FILE) +
  96                 global_page_state(NR_INACTIVE_ANON) +
  97                 global_page_state(NR_INACTIVE_FILE);
  98         if (sc->nr_to_scan <= 0 || min_adj == OOM_ADJUST_MAX + 1) {
  99                 lowmem_print(5, "lowmem_shrink %lu, %x, return %d\n",
 100                              sc->nr_to_scan, sc->gfp_mask, rem);
 101                 return rem;
 102         }
 103         selected_oom_adj = min_adj;
 104
 105         read_lock(&tasklist_lock);
 106         for_each_process(p) {
 107                 struct mm_struct *mm;
 108                 struct signal_struct *sig;
 109                 int oom_adj;
 110
 111                 if (test_tsk_thread_flag(p, TIF_MEMDIE) &&
 112                     time_before_eq(jiffies, lowmem_deathpending_timeout)) {
 113                         read_unlock(&tasklist_lock);
 114                         return 0;
 115                 }
 116                 task_lock(p);
 117                 mm = p->mm;
 118                 sig = p->signal;
 119                 if (!mm || !sig) {
 120                         task_unlock(p);
 121                         continue;
 122                 }
 123                 oom_adj = sig->oom_adj;
 124                 if (oom_adj < min_adj) {
 125                         task_unlock(p);
 126                         continue;
 127                 }
 128                 tasksize = get_mm_rss(mm);
 129                 task_unlock(p);
 130                 if (tasksize <= 0)
 131                         continue;
 132                 if (selected) {
 133                         if (oom_adj < selected_oom_adj)
 134                                 continue;
 135                         if (oom_adj == selected_oom_adj &&
 136                             tasksize <= selected_tasksize)
 137                                 continue;
 138                 }
 139                 selected = p;
 140                 selected_tasksize = tasksize;
 141                 selected_oom_adj = oom_adj;
 142                 lowmem_print(2, "select %d (%s), adj %d, size %d, to kill\n",
 143                              p->pid, p->comm, oom_adj, tasksize);
 144         }
 145         if (selected) {
 146                 lowmem_print(1, "send sigkill to %d (%s), adj %d, size %d\n",
 147                              selected->pid, selected->comm,
 148                              selected_oom_adj, selected_tasksize);
 149                 lowmem_deathpending_timeout = jiffies + HZ;
 150                 force_sig(SIGKILL, selected);
 151                 set_tsk_thread_flag(selected, TIF_MEMDIE);
 152                 rem -= selected_tasksize;
 153         }
 154         lowmem_print(4, "lowmem_shrink %lu, %x, return %d\n",
 155                      sc->nr_to_scan, sc->gfp_mask, rem);
 156         read_unlock(&tasklist_lock);
 157         return rem;
 158 }
 159
 160 static struct shrinker lowmem_shrinker = {
 161         .shrink = lowmem_shrink,
 162         .seeks = DEFAULT_SEEKS * 16
 163 };
 164
 165 static int __init lowmem_init(void)
 166 {
 167         register_shrinker(&lowmem_shrinker);
 168         return 0;
 169 }
 170
 171 static void __exit lowmem_exit(void)
 172 {
 173         unregister_shrinker(&lowmem_shrinker);
 174 }
 175
 176 module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR);
 177 module_param_array_named(adj, lowmem_adj, int, &lowmem_adj_size,
 178                          S_IRUGO | S_IWUSR);
 179 module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
 180                          S_IRUGO | S_IWUSR);
 181 module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR);
 182
 183 module_init(lowmem_init);
 184 module_exit(lowmem_exit);
 185
 186 MODULE_LICENSE("GPL");
 187