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 #define CREATE_TRACE_POINTS
  45 #include "trace/lowmemorykiller.h"
  46
  47 static uint32_t lowmem_debug_level = 1;
  48 static short lowmem_adj[6] = {
  49         0,
  50         1,
  51         6,
  52         12,
  53 };
  54 static int lowmem_adj_size = 4;
  55 static int lowmem_minfree[6] = {
  56         3 * 512,        /* 6MB */
  57         2 * 1024,       /* 8MB */
  58         4 * 1024,       /* 16MB */
  59         16 * 1024,      /* 64MB */
  60 };
  61 static int lowmem_minfree_size = 4;
  62
  63 static unsigned long lowmem_deathpending_timeout;
  64
  65 #define lowmem_print(level, x...)                       \
  66         do {                                            \
  67                 if (lowmem_debug_level >= (level))      \
  68                         pr_info(x);                     \
  69         } while (0)
  70
  71 static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
  72 {
  73         struct task_struct *tsk;
  74         struct task_struct *selected = NULL;
  75         int rem = 0;
  76         int tasksize;
  77         int i;
  78         short min_score_adj = OOM_SCORE_ADJ_MAX + 1;
  79         int minfree = 0;
  80         int selected_tasksize = 0;
  81         short selected_oom_score_adj;
  82         int array_size = ARRAY_SIZE(lowmem_adj);
  83         int other_free = global_page_state(NR_FREE_PAGES) - totalreserve_pages -
  84                                                 global_page_state(NR_FREE_CMA_PAGES);
  85         int other_file = global_page_state(NR_FILE_PAGES) -
  86                                                 global_page_state(NR_SHMEM);
  87
  88         if (lowmem_adj_size < array_size)
  89                 array_size = lowmem_adj_size;
  90         if (lowmem_minfree_size < array_size)
  91                 array_size = lowmem_minfree_size;
  92         for (i = 0; i < array_size; i++) {
  93                 minfree = lowmem_minfree[i];
  94                 if (other_free < minfree && other_file < minfree) {
  95                         min_score_adj = lowmem_adj[i];
  96                         break;
  97                 }
  98         }
  99         if (sc->nr_to_scan > 0)
 100                 lowmem_print(3, "lowmem_shrink %lu, %x, ofree %d %d, ma %hd\n",
 101                                 sc->nr_to_scan, sc->gfp_mask, other_free,
 102                                 other_file, min_score_adj);
 103         rem = global_page_state(NR_ACTIVE_ANON) +
 104                 global_page_state(NR_ACTIVE_FILE) +
 105                 global_page_state(NR_INACTIVE_ANON) +
 106                 global_page_state(NR_INACTIVE_FILE);
 107         if (sc->nr_to_scan <= 0 || min_score_adj == OOM_SCORE_ADJ_MAX + 1) {
 108                 lowmem_print(5, "lowmem_shrink %lu, %x, return %d\n",
 109                              sc->nr_to_scan, sc->gfp_mask, rem);
 110                 return rem;
 111         }
 112         selected_oom_score_adj = min_score_adj;
 113
 114         rcu_read_lock();
 115         for_each_process(tsk) {
 116                 struct task_struct *p;
 117                 short oom_score_adj;
 118
 119                 if (tsk->flags & PF_KTHREAD)
 120                         continue;
 121
 122                 p = find_lock_task_mm(tsk);
 123                 if (!p)
 124                         continue;
 125
 126                 if (test_tsk_thread_flag(p, TIF_MEMDIE) &&
 127                     time_before_eq(jiffies, lowmem_deathpending_timeout)) {
 128                         task_unlock(p);
 129                         rcu_read_unlock();
 130                         return 0;
 131                 }
 132                 oom_score_adj = p->signal->oom_score_adj;
 133                 if (oom_score_adj < min_score_adj) {
 134                         task_unlock(p);
 135                         continue;
 136                 }
 137                 tasksize = get_mm_rss(p->mm);
 138                 task_unlock(p);
 139                 if (tasksize <= 0)
 140                         continue;
 141                 if (selected) {
 142                         if (oom_score_adj < selected_oom_score_adj)
 143                                 continue;
 144                         if (oom_score_adj == selected_oom_score_adj &&
 145                             tasksize <= selected_tasksize)
 146                                 continue;
 147                 }
 148                 selected = p;
 149                 selected_tasksize = tasksize;
 150                 selected_oom_score_adj = oom_score_adj;
 151                 lowmem_print(2, "select '%s' (%d), adj %hd, size %d, to kill\n",
 152                              p->comm, p->pid, oom_score_adj, tasksize);
 153         }
 154         if (selected) {
 155                 long cache_size = other_file * (long)(PAGE_SIZE / 1024);
 156                 long cache_limit = minfree * (long)(PAGE_SIZE / 1024);
 157                 long free = other_free * (long)(PAGE_SIZE / 1024);
 158                 trace_lowmemory_kill(selected, cache_size, cache_limit, free);
 159                 lowmem_print(1, "Killing '%s' (%d), adj %hd,\n" \
 160                                 "   to free %ldkB on behalf of '%s' (%d) because\n" \
 161                                 "   cache %ldkB is below limit %ldkB for oom_score_adj %hd\n" \
 162                                 "   Free memory is %ldkB above reserved\n",
 163                              selected->comm, selected->pid,
 164                              selected_oom_score_adj,
 165                              selected_tasksize * (long)(PAGE_SIZE / 1024),
 166                              current->comm, current->pid,
 167                              cache_size, cache_limit,
 168                              min_score_adj,
 169                              free);
 170                 lowmem_deathpending_timeout = jiffies + HZ;
 171                 send_sig(SIGKILL, selected, 0);
 172                 set_tsk_thread_flag(selected, TIF_MEMDIE);
 173                 rem -= selected_tasksize;
 174         }
 175         lowmem_print(4, "lowmem_shrink %lu, %x, return %d\n",
 176                      sc->nr_to_scan, sc->gfp_mask, rem);
 177         rcu_read_unlock();
 178         return rem;
 179 }
 180
 181 static struct shrinker lowmem_shrinker = {
 182         .shrink = lowmem_shrink,
 183         .seeks = DEFAULT_SEEKS * 16
 184 };
 185
 186 static int __init lowmem_init(void)
 187 {
 188         register_shrinker(&lowmem_shrinker);
 189         return 0;
 190 }
 191
 192 static void __exit lowmem_exit(void)
 193 {
 194         unregister_shrinker(&lowmem_shrinker);
 195 }
 196
 197 #ifdef CONFIG_ANDROID_LOW_MEMORY_KILLER_AUTODETECT_OOM_ADJ_VALUES
 198 static short lowmem_oom_adj_to_oom_score_adj(short oom_adj)
 199 {
 200         if (oom_adj == OOM_ADJUST_MAX)
 201                 return OOM_SCORE_ADJ_MAX;
 202         else
 203                 return (oom_adj * OOM_SCORE_ADJ_MAX) / -OOM_DISABLE;
 204 }
 205
 206 static void lowmem_autodetect_oom_adj_values(void)
 207 {
 208         int i;
 209         short oom_adj;
 210         short oom_score_adj;
 211         int array_size = ARRAY_SIZE(lowmem_adj);
 212
 213         if (lowmem_adj_size < array_size)
 214                 array_size = lowmem_adj_size;
 215
 216         if (array_size <= 0)
 217                 return;
 218
 219         oom_adj = lowmem_adj[array_size - 1];
 220         if (oom_adj > OOM_ADJUST_MAX)
 221                 return;
 222
 223         oom_score_adj = lowmem_oom_adj_to_oom_score_adj(oom_adj);
 224         if (oom_score_adj <= OOM_ADJUST_MAX)
 225                 return;
 226
 227         lowmem_print(1, "lowmem_shrink: convert oom_adj to oom_score_adj:\n");
 228         for (i = 0; i < array_size; i++) {
 229                 oom_adj = lowmem_adj[i];
 230                 oom_score_adj = lowmem_oom_adj_to_oom_score_adj(oom_adj);
 231                 lowmem_adj[i] = oom_score_adj;
 232                 lowmem_print(1, "oom_adj %d => oom_score_adj %d\n",
 233                              oom_adj, oom_score_adj);
 234         }
 235 }
 236
 237 static int lowmem_adj_array_set(const char *val, const struct kernel_param *kp)
 238 {
 239         int ret;
 240
 241         ret = param_array_ops.set(val, kp);
 242
 243         /* HACK: Autodetect oom_adj values in lowmem_adj array */
 244         lowmem_autodetect_oom_adj_values();
 245
 246         return ret;
 247 }
 248
 249 static int lowmem_adj_array_get(char *buffer, const struct kernel_param *kp)
 250 {
 251         return param_array_ops.get(buffer, kp);
 252 }
 253
 254 static void lowmem_adj_array_free(void *arg)
 255 {
 256         param_array_ops.free(arg);
 257 }
 258
 259 static struct kernel_param_ops lowmem_adj_array_ops = {
 260         .set = lowmem_adj_array_set,
 261         .get = lowmem_adj_array_get,
 262         .free = lowmem_adj_array_free,
 263 };
 264
 265 static const struct kparam_array __param_arr_adj = {
 266         .max = ARRAY_SIZE(lowmem_adj),
 267         .num = &lowmem_adj_size,
 268         .ops = &param_ops_short,
 269         .elemsize = sizeof(lowmem_adj[0]),
 270         .elem = lowmem_adj,
 271 };
 272 #endif
 273
 274 module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR);
 275 #ifdef CONFIG_ANDROID_LOW_MEMORY_KILLER_AUTODETECT_OOM_ADJ_VALUES
 276 __module_param_call(MODULE_PARAM_PREFIX, adj,
 277                     &lowmem_adj_array_ops,
 278                     .arr = &__param_arr_adj,
 279                     S_IRUGO | S_IWUSR, -1);
 280 __MODULE_PARM_TYPE(adj, "array of short");
 281 #else
 282 module_param_array_named(adj, lowmem_adj, short, &lowmem_adj_size,
 283                          S_IRUGO | S_IWUSR);
 284 #endif
 285 module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
 286                          S_IRUGO | S_IWUSR);
 287 module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR);
 288
 289 module_init(lowmem_init);
 290 module_exit(lowmem_exit);
 291
 292 MODULE_LICENSE("GPL");
 293