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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  34
  35 #include <linux/module.h>
  36 #include <linux/kernel.h>
  37 #include <linux/mm.h>
  38 #include <linux/oom.h>
  39 #include <linux/sched.h>
  40 #include <linux/swap.h>
  41 #include <linux/rcupdate.h>
  42 #include <linux/notifier.h>
  43
  44 static uint32_t lowmem_debug_level = 1;
  45 static short lowmem_adj[6] = {
  46         0,
  47         1,
  48         6,
  49         12,
  50 };
  51 static int lowmem_adj_size = 4;
  52 static int lowmem_minfree[6] = {
  53         3 * 512,        /* 6MB */
  54         2 * 1024,       /* 8MB */
  55         4 * 1024,       /* 16MB */
  56         16 * 1024,      /* 64MB */
  57 };
  58 static int lowmem_minfree_size = 4;
  59
  60 static unsigned long lowmem_deathpending_timeout;
  61
  62 #define lowmem_print(level, x...)                       \
  63         do {                                            \
  64                 if (lowmem_debug_level >= (level))      \
  65                         pr_info(x);                     \
  66         } while (0)
  67
  68 static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
  69 {
  70         struct task_struct *tsk;
  71         struct task_struct *selected = NULL;
  72         int rem = 0;
  73         int tasksize;
  74         int i;
  75         short min_score_adj = OOM_SCORE_ADJ_MAX + 1;
  76         int minfree = 0;
  77         int selected_tasksize = 0;
  78         short selected_oom_score_adj;
  79         int array_size = ARRAY_SIZE(lowmem_adj);
  80         int other_free = global_page_state(NR_FREE_PAGES) - totalreserve_pages;
  81         int other_file = global_page_state(NR_FILE_PAGES) -
  82                                                 global_page_state(NR_SHMEM);
  83
  84         if (lowmem_adj_size < array_size)
  85                 array_size = lowmem_adj_size;
  86         if (lowmem_minfree_size < array_size)
  87                 array_size = lowmem_minfree_size;
  88         for (i = 0; i < array_size; i++) {
  89                 minfree = lowmem_minfree[i];
  90                 if (other_free < minfree && other_file < minfree) {
  91                         min_score_adj = lowmem_adj[i];
  92                         break;
  93                 }
  94         }
  95         if (sc->nr_to_scan > 0)
  96                 lowmem_print(3, "lowmem_shrink %lu, %x, ofree %d %d, ma %hd\n",
  97                                 sc->nr_to_scan, sc->gfp_mask, other_free,
  98                                 other_file, min_score_adj);
  99         rem = global_page_state(NR_ACTIVE_ANON) +
 100                 global_page_state(NR_ACTIVE_FILE) +
 101                 global_page_state(NR_INACTIVE_ANON) +
 102                 global_page_state(NR_INACTIVE_FILE);
 103         if (sc->nr_to_scan <= 0 || min_score_adj == OOM_SCORE_ADJ_MAX + 1) {
 104                 lowmem_print(5, "lowmem_shrink %lu, %x, return %d\n",
 105                              sc->nr_to_scan, sc->gfp_mask, rem);
 106                 return rem;
 107         }
 108         selected_oom_score_adj = min_score_adj;
 109
 110         rcu_read_lock();
 111         for_each_process(tsk) {
 112                 struct task_struct *p;
 113                 short oom_score_adj;
 114
 115                 if (tsk->flags & PF_KTHREAD)
 116                         continue;
 117
 118                 p = find_lock_task_mm(tsk);
 119                 if (!p)
 120                         continue;
 121
 122                 if (test_tsk_thread_flag(p, TIF_MEMDIE) &&
 123                     time_before_eq(jiffies, lowmem_deathpending_timeout)) {
 124                         task_unlock(p);
 125                         rcu_read_unlock();
 126                         return 0;
 127                 }
 128                 oom_score_adj = p->signal->oom_score_adj;
 129                 if (oom_score_adj < min_score_adj) {
 130                         task_unlock(p);
 131                         continue;
 132                 }
 133                 tasksize = get_mm_rss(p->mm);
 134                 task_unlock(p);
 135                 if (tasksize <= 0)
 136                         continue;
 137                 if (selected) {
 138                         if (oom_score_adj < selected_oom_score_adj)
 139                                 continue;
 140                         if (oom_score_adj == selected_oom_score_adj &&
 141                             tasksize <= selected_tasksize)
 142                                 continue;
 143                 }
 144                 selected = p;
 145                 selected_tasksize = tasksize;
 146                 selected_oom_score_adj = oom_score_adj;
 147                 lowmem_print(2, "select '%s' (%d), adj %hd, size %d, to kill\n",
 148                              p->comm, p->pid, oom_score_adj, tasksize);
 149         }
 150         if (selected) {
 151                 lowmem_print(1, "Killing '%s' (%d), adj %hd,\n" \
 152                                 "   to free %ldkB on behalf of '%s' (%d) because\n" \
 153                                 "   cache %ldkB is below limit %ldkB for oom_score_adj %hd\n" \
 154                                 "   Free memory is %ldkB above reserved\n",
 155                              selected->comm, selected->pid,
 156                              selected_oom_score_adj,
 157                              selected_tasksize * (long)(PAGE_SIZE / 1024),
 158                              current->comm, current->pid,
 159                              other_file * (long)(PAGE_SIZE / 1024),
 160                              minfree * (long)(PAGE_SIZE / 1024),
 161                              min_score_adj,
 162                              other_free * (long)(PAGE_SIZE / 1024));
 163                 lowmem_deathpending_timeout = jiffies + HZ;
 164                 send_sig(SIGKILL, selected, 0);
 165                 set_tsk_thread_flag(selected, TIF_MEMDIE);
 166                 rem -= selected_tasksize;
 167         }
 168         lowmem_print(4, "lowmem_shrink %lu, %x, return %d\n",
 169                      sc->nr_to_scan, sc->gfp_mask, rem);
 170         rcu_read_unlock();
 171         return rem;
 172 }
 173
 174 static struct shrinker lowmem_shrinker = {
 175         .shrink = lowmem_shrink,
 176         .seeks = DEFAULT_SEEKS * 16
 177 };
 178
 179 static int __init lowmem_init(void)
 180 {
 181         register_shrinker(&lowmem_shrinker);
 182         return 0;
 183 }
 184
 185 static void __exit lowmem_exit(void)
 186 {
 187         unregister_shrinker(&lowmem_shrinker);
 188 }
 189
 190 #ifdef CONFIG_ANDROID_LOW_MEMORY_KILLER_AUTODETECT_OOM_ADJ_VALUES
 191 static short lowmem_oom_adj_to_oom_score_adj(short oom_adj)
 192 {
 193         if (oom_adj == OOM_ADJUST_MAX)
 194                 return OOM_SCORE_ADJ_MAX;
 195         else
 196                 return (oom_adj * OOM_SCORE_ADJ_MAX) / -OOM_DISABLE;
 197 }
 198
 199 static void lowmem_autodetect_oom_adj_values(void)
 200 {
 201         int i;
 202         short oom_adj;
 203         short oom_score_adj;
 204         int array_size = ARRAY_SIZE(lowmem_adj);
 205
 206         if (lowmem_adj_size < array_size)
 207                 array_size = lowmem_adj_size;
 208
 209         if (array_size <= 0)
 210                 return;
 211
 212         oom_adj = lowmem_adj[array_size - 1];
 213         if (oom_adj > OOM_ADJUST_MAX)
 214                 return;
 215
 216         oom_score_adj = lowmem_oom_adj_to_oom_score_adj(oom_adj);
 217         if (oom_score_adj <= OOM_ADJUST_MAX)
 218                 return;
 219
 220         lowmem_print(1, "lowmem_shrink: convert oom_adj to oom_score_adj:\n");
 221         for (i = 0; i < array_size; i++) {
 222                 oom_adj = lowmem_adj[i];
 223                 oom_score_adj = lowmem_oom_adj_to_oom_score_adj(oom_adj);
 224                 lowmem_adj[i] = oom_score_adj;
 225                 lowmem_print(1, "oom_adj %d => oom_score_adj %d\n",
 226                              oom_adj, oom_score_adj);
 227         }
 228 }
 229
 230 static int lowmem_adj_array_set(const char *val, const struct kernel_param *kp)
 231 {
 232         int ret;
 233
 234         ret = param_array_ops.set(val, kp);
 235
 236         /* HACK: Autodetect oom_adj values in lowmem_adj array */
 237         lowmem_autodetect_oom_adj_values();
 238
 239         return ret;
 240 }
 241
 242 static int lowmem_adj_array_get(char *buffer, const struct kernel_param *kp)
 243 {
 244         return param_array_ops.get(buffer, kp);
 245 }
 246
 247 static void lowmem_adj_array_free(void *arg)
 248 {
 249         param_array_ops.free(arg);
 250 }
 251
 252 static struct kernel_param_ops lowmem_adj_array_ops = {
 253         .set = lowmem_adj_array_set,
 254         .get = lowmem_adj_array_get,
 255         .free = lowmem_adj_array_free,
 256 };
 257
 258 static const struct kparam_array __param_arr_adj = {
 259         .max = ARRAY_SIZE(lowmem_adj),
 260         .num = &lowmem_adj_size,
 261         .ops = &param_ops_short,
 262         .elemsize = sizeof(lowmem_adj[0]),
 263         .elem = lowmem_adj,
 264 };
 265 #endif
 266
 267 module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR);
 268 #ifdef CONFIG_ANDROID_LOW_MEMORY_KILLER_AUTODETECT_OOM_ADJ_VALUES
 269 __module_param_call(MODULE_PARAM_PREFIX, adj,
 270                     &lowmem_adj_array_ops,
 271                     .arr = &__param_arr_adj,
 272                     S_IRUGO | S_IWUSR, -1);
 273 __MODULE_PARM_TYPE(adj, "array of short");
 274 #else
 275 module_param_array_named(adj, lowmem_adj, short, &lowmem_adj_size,
 276                          S_IRUGO | S_IWUSR);
 277 #endif
 278 module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
 279                          S_IRUGO | S_IWUSR);
 280 module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR);
 281
 282 module_init(lowmem_init);
 283 module_exit(lowmem_exit);
 284
 285 MODULE_LICENSE("GPL");
 286