lowmemorykiller.c revision c034ef70c63ff50b8c963c275909d2c4dd1a962e
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 44static uint32_t lowmem_debug_level = 1; 45static short lowmem_adj[6] = { 46 0, 47 1, 48 6, 49 12, 50}; 51static int lowmem_adj_size = 4; 52static int lowmem_minfree[6] = { 53 3 * 512, /* 6MB */ 54 2 * 1024, /* 8MB */ 55 4 * 1024, /* 16MB */ 56 16 * 1024, /* 64MB */ 57}; 58static int lowmem_minfree_size = 4; 59 60static 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 68static unsigned long lowmem_count(struct shrinker *s, 69 struct shrink_control *sc) 70{ 71 return global_page_state(NR_ACTIVE_ANON) + 72 global_page_state(NR_ACTIVE_FILE) + 73 global_page_state(NR_INACTIVE_ANON) + 74 global_page_state(NR_INACTIVE_FILE); 75} 76 77static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc) 78{ 79 struct task_struct *tsk; 80 struct task_struct *selected = NULL; 81 unsigned long rem = 0; 82 int tasksize; 83 int i; 84 short min_score_adj = OOM_SCORE_ADJ_MAX + 1; 85 int selected_tasksize = 0; 86 short selected_oom_score_adj; 87 int array_size = ARRAY_SIZE(lowmem_adj); 88 int other_free = global_page_state(NR_FREE_PAGES) - totalreserve_pages; 89 int other_file = global_page_state(NR_FILE_PAGES) - 90 global_page_state(NR_SHMEM) - 91 total_swapcache_pages(); 92 93 if (lowmem_adj_size < array_size) 94 array_size = lowmem_adj_size; 95 if (lowmem_minfree_size < array_size) 96 array_size = lowmem_minfree_size; 97 for (i = 0; i < array_size; i++) { 98 if (other_free < lowmem_minfree[i] && 99 other_file < lowmem_minfree[i]) { 100 min_score_adj = lowmem_adj[i]; 101 break; 102 } 103 } 104 105 lowmem_print(3, "lowmem_scan %lu, %x, ofree %d %d, ma %hd\n", 106 sc->nr_to_scan, sc->gfp_mask, other_free, 107 other_file, min_score_adj); 108 109 if (min_score_adj == OOM_SCORE_ADJ_MAX + 1) { 110 lowmem_print(5, "lowmem_scan %lu, %x, return 0\n", 111 sc->nr_to_scan, sc->gfp_mask); 112 return 0; 113 } 114 115 selected_oom_score_adj = min_score_adj; 116 117 rcu_read_lock(); 118 for_each_process(tsk) { 119 struct task_struct *p; 120 short oom_score_adj; 121 122 if (tsk->flags & PF_KTHREAD) 123 continue; 124 125 p = find_lock_task_mm(tsk); 126 if (!p) 127 continue; 128 129 if (test_tsk_thread_flag(p, TIF_MEMDIE) && 130 time_before_eq(jiffies, lowmem_deathpending_timeout)) { 131 task_unlock(p); 132 rcu_read_unlock(); 133 return 0; 134 } 135 oom_score_adj = p->signal->oom_score_adj; 136 if (oom_score_adj < min_score_adj) { 137 task_unlock(p); 138 continue; 139 } 140 tasksize = get_mm_rss(p->mm); 141 task_unlock(p); 142 if (tasksize <= 0) 143 continue; 144 if (selected) { 145 if (oom_score_adj < selected_oom_score_adj) 146 continue; 147 if (oom_score_adj == selected_oom_score_adj && 148 tasksize <= selected_tasksize) 149 continue; 150 } 151 selected = p; 152 selected_tasksize = tasksize; 153 selected_oom_score_adj = oom_score_adj; 154 lowmem_print(2, "select %d (%s), adj %hd, size %d, to kill\n", 155 p->pid, p->comm, oom_score_adj, tasksize); 156 } 157 if (selected) { 158 lowmem_print(1, "send sigkill to %d (%s), adj %hd, size %d\n", 159 selected->pid, selected->comm, 160 selected_oom_score_adj, selected_tasksize); 161 lowmem_deathpending_timeout = jiffies + HZ; 162 set_tsk_thread_flag(selected, TIF_MEMDIE); 163 send_sig(SIGKILL, selected, 0); 164 rem += selected_tasksize; 165 } 166 167 lowmem_print(4, "lowmem_scan %lu, %x, return %lu\n", 168 sc->nr_to_scan, sc->gfp_mask, rem); 169 rcu_read_unlock(); 170 return rem; 171} 172 173static struct shrinker lowmem_shrinker = { 174 .scan_objects = lowmem_scan, 175 .count_objects = lowmem_count, 176 .seeks = DEFAULT_SEEKS * 16 177}; 178 179static int __init lowmem_init(void) 180{ 181 register_shrinker(&lowmem_shrinker); 182 return 0; 183} 184 185static void __exit lowmem_exit(void) 186{ 187 unregister_shrinker(&lowmem_shrinker); 188} 189 190#ifdef CONFIG_ANDROID_LOW_MEMORY_KILLER_AUTODETECT_OOM_ADJ_VALUES 191static 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 199static 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 230static 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 242static int lowmem_adj_array_get(char *buffer, const struct kernel_param *kp) 243{ 244 return param_array_ops.get(buffer, kp); 245} 246 247static void lowmem_adj_array_free(void *arg) 248{ 249 param_array_ops.free(arg); 250} 251 252static 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 258static const struct kparam_array __param_arr_adj = { 259 .max = ARRAY_SIZE(lowmem_adj), 260 .num = &lowmem_adj_size, 261 .ops = ¶m_ops_short, 262 .elemsize = sizeof(lowmem_adj[0]), 263 .elem = lowmem_adj, 264}; 265#endif 266 267module_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 275module_param_array_named(adj, lowmem_adj, short, &lowmem_adj_size, 276 S_IRUGO | S_IWUSR); 277#endif 278module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size, 279 S_IRUGO | S_IWUSR); 280module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR); 281 282module_init(lowmem_init); 283module_exit(lowmem_exit); 284 285MODULE_LICENSE("GPL"); 286 287