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 #include <linux/notifier.h>
  38
  39 static uint32_t lowmem_debug_level = 2;
  40 static int lowmem_adj[6] = {
  41         0,
  42         1,
  43         6,
  44         12,
  45 };
  46 static int lowmem_adj_size = 4;
  47 static size_t lowmem_minfree[6] = {
  48         3 * 512,        /* 6MB */
  49         2 * 1024,       /* 8MB */
  50         4 * 1024,       /* 16MB */
  51         16 * 1024,      /* 64MB */
  52 };
  53 static int lowmem_minfree_size = 4;
  54
  55 static struct task_struct *lowmem_deathpending;
  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
  65 task_notify_func(struct notifier_block *self, unsigned long val, void *data);
  66
  67 static struct notifier_block task_nb = {
  68         .notifier_call  = task_notify_func,
  69 };
  70
  71 static int
  72 task_notify_func(struct notifier_block *self, unsigned long val, void *data)
  73 {
  74         struct task_struct *task = data;
  75
  76         if (task == lowmem_deathpending)
  77                 lowmem_deathpending = NULL;
  78
  79         return NOTIFY_OK;
  80 }
  81
  82 static int lowmem_shrink(struct shrinker *s, int nr_to_scan, gfp_t gfp_mask)
  83 {
  84         struct task_struct *p;
  85         struct task_struct *selected = NULL;
  86         int rem = 0;
  87         int tasksize;
  88         int i;
  89         int min_adj = OOM_ADJUST_MAX + 1;
  90         int selected_tasksize = 0;
  91         int selected_oom_adj;
  92         int array_size = ARRAY_SIZE(lowmem_adj);
  93         int other_free = global_page_state(NR_FREE_PAGES);
  94         int other_file = global_page_state(NR_FILE_PAGES) -
  95                                                 global_page_state(NR_SHMEM);
  96
  97         /*
  98          * If we already have a death outstanding, then
  99          * bail out right away; indicating to vmscan
 100          * that we have nothing further to offer on
 101          * this pass.
 102          *
 103          */
 104         if (lowmem_deathpending &&
 105             time_before_eq(jiffies, lowmem_deathpending_timeout))
 106                 return 0;
 107
 108         if (lowmem_adj_size < array_size)
 109                 array_size = lowmem_adj_size;
 110         if (lowmem_minfree_size < array_size)
 111                 array_size = lowmem_minfree_size;
 112         for (i = 0; i < array_size; i++) {
 113                 if (other_free < lowmem_minfree[i] &&
 114                     other_file < lowmem_minfree[i]) {
 115                         min_adj = lowmem_adj[i];
 116                         break;
 117                 }
 118         }
 119         if (nr_to_scan > 0)
 120                 lowmem_print(3, "lowmem_shrink %d, %x, ofree %d %d, ma %d\n",
 121                              nr_to_scan, gfp_mask, other_free, other_file,
 122                              min_adj);
 123         rem = global_page_state(NR_ACTIVE_ANON) +
 124                 global_page_state(NR_ACTIVE_FILE) +
 125                 global_page_state(NR_INACTIVE_ANON) +
 126                 global_page_state(NR_INACTIVE_FILE);
 127         if (nr_to_scan <= 0 || min_adj == OOM_ADJUST_MAX + 1) {
 128                 lowmem_print(5, "lowmem_shrink %d, %x, return %d\n",
 129                              nr_to_scan, gfp_mask, rem);
 130                 return rem;
 131         }
 132         selected_oom_adj = min_adj;
 133
 134         read_lock(&tasklist_lock);
 135         for_each_process(p) {
 136                 struct mm_struct *mm;
 137                 struct signal_struct *sig;
 138                 int oom_adj;
 139
 140                 task_lock(p);
 141                 mm = p->mm;
 142                 sig = p->signal;
 143                 if (!mm || !sig) {
 144                         task_unlock(p);
 145                         continue;
 146                 }
 147                 oom_adj = sig->oom_adj;
 148                 if (oom_adj < min_adj) {
 149                         task_unlock(p);
 150                         continue;
 151                 }
 152                 tasksize = get_mm_rss(mm);
 153                 task_unlock(p);
 154                 if (tasksize <= 0)
 155                         continue;
 156                 if (selected) {
 157                         if (oom_adj < selected_oom_adj)
 158                                 continue;
 159                         if (oom_adj == selected_oom_adj &&
 160                             tasksize <= selected_tasksize)
 161                                 continue;
 162                 }
 163                 selected = p;
 164                 selected_tasksize = tasksize;
 165                 selected_oom_adj = oom_adj;
 166                 lowmem_print(2, "select %d (%s), adj %d, size %d, to kill\n",
 167                              p->pid, p->comm, oom_adj, tasksize);
 168         }
 169         if (selected) {
 170                 lowmem_print(1, "send sigkill to %d (%s), adj %d, size %d\n",
 171                              selected->pid, selected->comm,
 172                              selected_oom_adj, selected_tasksize);
 173                 lowmem_deathpending = selected;
 174                 lowmem_deathpending_timeout = jiffies + HZ;
 175                 force_sig(SIGKILL, selected);
 176                 rem -= selected_tasksize;
 177         }
 178         lowmem_print(4, "lowmem_shrink %d, %x, return %d\n",
 179                      nr_to_scan, gfp_mask, rem);
 180         read_unlock(&tasklist_lock);
 181         return rem;
 182 }
 183
 184 static struct shrinker lowmem_shrinker = {
 185         .shrink = lowmem_shrink,
 186         .seeks = DEFAULT_SEEKS * 16
 187 };
 188
 189 static int __init lowmem_init(void)
 190 {
 191         task_free_register(&task_nb);
 192         register_shrinker(&lowmem_shrinker);
 193         return 0;
 194 }
 195
 196 static void __exit lowmem_exit(void)
 197 {
 198         unregister_shrinker(&lowmem_shrinker);
 199         task_free_unregister(&task_nb);
 200 }
 201
 202 module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR);
 203 module_param_array_named(adj, lowmem_adj, int, &lowmem_adj_size,
 204                          S_IRUGO | S_IWUSR);
 205 module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
 206                          S_IRUGO | S_IWUSR);
 207 module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR);
 208
 209 module_init(lowmem_init);
 210 module_exit(lowmem_exit);
 211
 212 MODULE_LICENSE("GPL");
 213