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                                                 global_page_state(NR_FREE_CMA_PAGES);
  82         int other_file = global_page_state(NR_FILE_PAGES) -
  83                                                 global_page_state(NR_SHMEM);
  84
  85         if (lowmem_adj_size < array_size)
  86                 array_size = lowmem_adj_size;
  87         if (lowmem_minfree_size < array_size)
  88                 array_size = lowmem_minfree_size;
  89         for (i = 0; i < array_size; i++) {
  90                 minfree = lowmem_minfree[i];
  91                 if (other_free < minfree && other_file < minfree) {
  92                         min_score_adj = lowmem_adj[i];
  93                         break;
  94                 }
  95         }
  96         if (sc->nr_to_scan > 0)
  97                 lowmem_print(3, "lowmem_shrink %lu, %x, ofree %d %d, ma %hd\n",
  98                                 sc->nr_to_scan, sc->gfp_mask, other_free,
  99                                 other_file, min_score_adj);
 100         rem = global_page_state(NR_ACTIVE_ANON) +
 101                 global_page_state(NR_ACTIVE_FILE) +
 102                 global_page_state(NR_INACTIVE_ANON) +
 103                 global_page_state(NR_INACTIVE_FILE);
 104         if (sc->nr_to_scan <= 0 || min_score_adj == OOM_SCORE_ADJ_MAX + 1) {
 105                 lowmem_print(5, "lowmem_shrink %lu, %x, return %d\n",
 106                              sc->nr_to_scan, sc->gfp_mask, rem);
 107                 return rem;
 108         }
 109         selected_oom_score_adj = min_score_adj;
 110
 111         rcu_read_lock();
 112         for_each_process(tsk) {
 113                 struct task_struct *p;
 114                 short oom_score_adj;
 115
 116                 if (tsk->flags & PF_KTHREAD)
 117                         continue;
 118
 119                 p = find_lock_task_mm(tsk);
 120                 if (!p)
 121                         continue;
 122
 123                 if (test_tsk_thread_flag(p, TIF_MEMDIE) &&
 124                     time_before_eq(jiffies, lowmem_deathpending_timeout)) {
 125                         task_unlock(p);
 126                         rcu_read_unlock();
 127                         return 0;
 128                 }
 129                 oom_score_adj = p->signal->oom_score_adj;
 130                 if (oom_score_adj < min_score_adj) {
 131                         task_unlock(p);
 132                         continue;
 133                 }
 134                 tasksize = get_mm_rss(p->mm);
 135                 task_unlock(p);
 136                 if (tasksize <= 0)
 137                         continue;
 138                 if (selected) {
 139                         if (oom_score_adj < selected_oom_score_adj)
 140                                 continue;
 141                         if (oom_score_adj == selected_oom_score_adj &&
 142                             tasksize <= selected_tasksize)
 143                                 continue;
 144                 }
 145                 selected = p;
 146                 selected_tasksize = tasksize;
 147                 selected_oom_score_adj = oom_score_adj;
 148                 lowmem_print(2, "select '%s' (%d), adj %hd, size %d, to kill\n",
 149                              p->comm, p->pid, oom_score_adj, tasksize);
 150         }
 151         if (selected) {
 152                 lowmem_print(1, "Killing '%s' (%d), adj %hd,\n" \
 153                                 "   to free %ldkB on behalf of '%s' (%d) because\n" \
 154                                 "   cache %ldkB is below limit %ldkB for oom_score_adj %hd\n" \
 155                                 "   Free memory is %ldkB above reserved\n",
 156                              selected->comm, selected->pid,
 157                              selected_oom_score_adj,
 158                              selected_tasksize * (long)(PAGE_SIZE / 1024),
 159                              current->comm, current->pid,
 160                              other_file * (long)(PAGE_SIZE / 1024),
 161                              minfree * (long)(PAGE_SIZE / 1024),
 162                              min_score_adj,
 163                              other_free * (long)(PAGE_SIZE / 1024));
 164                 lowmem_deathpending_timeout = jiffies + HZ;
 165                 send_sig(SIGKILL, selected, 0);
 166                 set_tsk_thread_flag(selected, TIF_MEMDIE);
 167                 rem -= selected_tasksize;
 168         }
 169         lowmem_print(4, "lowmem_shrink %lu, %x, return %d\n",
 170                      sc->nr_to_scan, sc->gfp_mask, rem);
 171         rcu_read_unlock();
 172         return rem;
 173 }
 174
 175 static struct shrinker lowmem_shrinker = {
 176         .shrink = lowmem_shrink,
 177         .seeks = DEFAULT_SEEKS * 16
 178 };
 179
 180 static int __init lowmem_init(void)
 181 {
 182         register_shrinker(&lowmem_shrinker);
 183         return 0;
 184 }
 185
 186 static void __exit lowmem_exit(void)
 187 {
 188         unregister_shrinker(&lowmem_shrinker);
 189 }
 190
 191 #ifdef CONFIG_ANDROID_LOW_MEMORY_KILLER_AUTODETECT_OOM_ADJ_VALUES
 192 static short lowmem_oom_adj_to_oom_score_adj(short oom_adj)
 193 {
 194         if (oom_adj == OOM_ADJUST_MAX)
 195                 return OOM_SCORE_ADJ_MAX;
 196         else
 197                 return (oom_adj * OOM_SCORE_ADJ_MAX) / -OOM_DISABLE;
 198 }
 199
 200 static void lowmem_autodetect_oom_adj_values(void)
 201 {
 202         int i;
 203         short oom_adj;
 204         short oom_score_adj;
 205         int array_size = ARRAY_SIZE(lowmem_adj);
 206
 207         if (lowmem_adj_size < array_size)
 208                 array_size = lowmem_adj_size;
 209
 210         if (array_size <= 0)
 211                 return;
 212
 213         oom_adj = lowmem_adj[array_size - 1];
 214         if (oom_adj > OOM_ADJUST_MAX)
 215                 return;
 216
 217         oom_score_adj = lowmem_oom_adj_to_oom_score_adj(oom_adj);
 218         if (oom_score_adj <= OOM_ADJUST_MAX)
 219                 return;
 220
 221         lowmem_print(1, "lowmem_shrink: convert oom_adj to oom_score_adj:\n");
 222         for (i = 0; i < array_size; i++) {
 223                 oom_adj = lowmem_adj[i];
 224                 oom_score_adj = lowmem_oom_adj_to_oom_score_adj(oom_adj);
 225                 lowmem_adj[i] = oom_score_adj;
 226                 lowmem_print(1, "oom_adj %d => oom_score_adj %d\n",
 227                              oom_adj, oom_score_adj);
 228         }
 229 }
 230
 231 static int lowmem_adj_array_set(const char *val, const struct kernel_param *kp)
 232 {
 233         int ret;
 234
 235         ret = param_array_ops.set(val, kp);
 236
 237         /* HACK: Autodetect oom_adj values in lowmem_adj array */
 238         lowmem_autodetect_oom_adj_values();
 239
 240         return ret;
 241 }
 242
 243 static int lowmem_adj_array_get(char *buffer, const struct kernel_param *kp)
 244 {
 245         return param_array_ops.get(buffer, kp);
 246 }
 247
 248 static void lowmem_adj_array_free(void *arg)
 249 {
 250         param_array_ops.free(arg);
 251 }
 252
 253 static struct kernel_param_ops lowmem_adj_array_ops = {
 254         .set = lowmem_adj_array_set,
 255         .get = lowmem_adj_array_get,
 256         .free = lowmem_adj_array_free,
 257 };
 258
 259 static const struct kparam_array __param_arr_adj = {
 260         .max = ARRAY_SIZE(lowmem_adj),
 261         .num = &lowmem_adj_size,
 262         .ops = &param_ops_short,
 263         .elemsize = sizeof(lowmem_adj[0]),
 264         .elem = lowmem_adj,
 265 };
 266 #endif
 267
 268 module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR);
 269 #ifdef CONFIG_ANDROID_LOW_MEMORY_KILLER_AUTODETECT_OOM_ADJ_VALUES
 270 __module_param_call(MODULE_PARAM_PREFIX, adj,
 271                     &lowmem_adj_array_ops,
 272                     .arr = &__param_arr_adj,
 273                     S_IRUGO | S_IWUSR, -1);
 274 __MODULE_PARM_TYPE(adj, "array of short");
 275 #else
 276 module_param_array_named(adj, lowmem_adj, short, &lowmem_adj_size,
 277                          S_IRUGO | S_IWUSR);
 278 #endif
 279 module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
 280                          S_IRUGO | S_IWUSR);
 281 module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR);
 282
 283 module_init(lowmem_init);
 284 module_exit(lowmem_exit);
 285
 286 MODULE_LICENSE("GPL");
 287