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 47static uint32_t lowmem_debug_level = 1; 48static short lowmem_adj[6] = { 49 0, 50 1, 51 6, 52 12, 53}; 54static int lowmem_adj_size = 4; 55static int lowmem_minfree[6] = { 56 3 * 512, /* 6MB */ 57 2 * 1024, /* 8MB */ 58 4 * 1024, /* 16MB */ 59 16 * 1024, /* 64MB */ 60}; 61static int lowmem_minfree_size = 4; 62 63static 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 71static unsigned long lowmem_count(struct shrinker *s, 72 struct shrink_control *sc) 73{ 74 return global_page_state(NR_ACTIVE_ANON) + 75 global_page_state(NR_ACTIVE_FILE) + 76 global_page_state(NR_INACTIVE_ANON) + 77 global_page_state(NR_INACTIVE_FILE); 78} 79 80static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc) 81{ 82 struct task_struct *tsk; 83 struct task_struct *selected = NULL; 84 unsigned long rem = 0; 85 int tasksize; 86 int i; 87 short min_score_adj = OOM_SCORE_ADJ_MAX + 1; 88 int minfree = 0; 89 int selected_tasksize = 0; 90 short selected_oom_score_adj; 91 int array_size = ARRAY_SIZE(lowmem_adj); 92 int other_free = global_page_state(NR_FREE_PAGES) - totalreserve_pages; 93 int other_file = global_page_state(NR_FILE_PAGES) - 94 global_page_state(NR_SHMEM) - 95 total_swapcache_pages(); 96 97 if (lowmem_adj_size < array_size) 98 array_size = lowmem_adj_size; 99 if (lowmem_minfree_size < array_size) 100 array_size = lowmem_minfree_size; 101 for (i = 0; i < array_size; i++) { 102 minfree = lowmem_minfree[i]; 103 if (other_free < minfree && other_file < minfree) { 104 min_score_adj = lowmem_adj[i]; 105 break; 106 } 107 } 108 109 lowmem_print(3, "lowmem_scan %lu, %x, ofree %d %d, ma %hd\n", 110 sc->nr_to_scan, sc->gfp_mask, other_free, 111 other_file, min_score_adj); 112 113 if (min_score_adj == OOM_SCORE_ADJ_MAX + 1) { 114 lowmem_print(5, "lowmem_scan %lu, %x, return 0\n", 115 sc->nr_to_scan, sc->gfp_mask); 116 return 0; 117 } 118 119 selected_oom_score_adj = min_score_adj; 120 121 rcu_read_lock(); 122 for_each_process(tsk) { 123 struct task_struct *p; 124 short oom_score_adj; 125 126 if (tsk->flags & PF_KTHREAD) 127 continue; 128 129 p = find_lock_task_mm(tsk); 130 if (!p) 131 continue; 132 133 if (test_tsk_thread_flag(p, TIF_MEMDIE) && 134 time_before_eq(jiffies, lowmem_deathpending_timeout)) { 135 task_unlock(p); 136 rcu_read_unlock(); 137 return 0; 138 } 139 oom_score_adj = p->signal->oom_score_adj; 140 if (oom_score_adj < min_score_adj) { 141 task_unlock(p); 142 continue; 143 } 144 tasksize = get_mm_rss(p->mm); 145 task_unlock(p); 146 if (tasksize <= 0) 147 continue; 148 if (selected) { 149 if (oom_score_adj < selected_oom_score_adj) 150 continue; 151 if (oom_score_adj == selected_oom_score_adj && 152 tasksize <= selected_tasksize) 153 continue; 154 } 155 selected = p; 156 selected_tasksize = tasksize; 157 selected_oom_score_adj = oom_score_adj; 158 lowmem_print(2, "select '%s' (%d), adj %hd, size %d, to kill\n", 159 p->comm, p->pid, oom_score_adj, tasksize); 160 } 161 if (selected) { 162 long cache_size = other_file * (long)(PAGE_SIZE / 1024); 163 long cache_limit = minfree * (long)(PAGE_SIZE / 1024); 164 long free = other_free * (long)(PAGE_SIZE / 1024); 165 trace_lowmemory_kill(selected, cache_size, cache_limit, free); 166 lowmem_print(1, "Killing '%s' (%d), adj %hd,\n" \ 167 " to free %ldkB on behalf of '%s' (%d) because\n" \ 168 " cache %ldkB is below limit %ldkB for oom_score_adj %hd\n" \ 169 " Free memory is %ldkB above reserved\n", 170 selected->comm, selected->pid, 171 selected_oom_score_adj, 172 selected_tasksize * (long)(PAGE_SIZE / 1024), 173 current->comm, current->pid, 174 cache_size, cache_limit, 175 min_score_adj, 176 free); 177 lowmem_deathpending_timeout = jiffies + HZ; 178 set_tsk_thread_flag(selected, TIF_MEMDIE); 179 send_sig(SIGKILL, selected, 0); 180 rem += selected_tasksize; 181 } 182 183 lowmem_print(4, "lowmem_scan %lu, %x, return %lu\n", 184 sc->nr_to_scan, sc->gfp_mask, rem); 185 rcu_read_unlock(); 186 return rem; 187} 188 189static struct shrinker lowmem_shrinker = { 190 .scan_objects = lowmem_scan, 191 .count_objects = lowmem_count, 192 .seeks = DEFAULT_SEEKS * 16 193}; 194 195static int __init lowmem_init(void) 196{ 197 register_shrinker(&lowmem_shrinker); 198 return 0; 199} 200 201static void __exit lowmem_exit(void) 202{ 203 unregister_shrinker(&lowmem_shrinker); 204} 205 206#ifdef CONFIG_ANDROID_LOW_MEMORY_KILLER_AUTODETECT_OOM_ADJ_VALUES 207static short lowmem_oom_adj_to_oom_score_adj(short oom_adj) 208{ 209 if (oom_adj == OOM_ADJUST_MAX) 210 return OOM_SCORE_ADJ_MAX; 211 else 212 return (oom_adj * OOM_SCORE_ADJ_MAX) / -OOM_DISABLE; 213} 214 215static void lowmem_autodetect_oom_adj_values(void) 216{ 217 int i; 218 short oom_adj; 219 short oom_score_adj; 220 int array_size = ARRAY_SIZE(lowmem_adj); 221 222 if (lowmem_adj_size < array_size) 223 array_size = lowmem_adj_size; 224 225 if (array_size <= 0) 226 return; 227 228 oom_adj = lowmem_adj[array_size - 1]; 229 if (oom_adj > OOM_ADJUST_MAX) 230 return; 231 232 oom_score_adj = lowmem_oom_adj_to_oom_score_adj(oom_adj); 233 if (oom_score_adj <= OOM_ADJUST_MAX) 234 return; 235 236 lowmem_print(1, "lowmem_shrink: convert oom_adj to oom_score_adj:\n"); 237 for (i = 0; i < array_size; i++) { 238 oom_adj = lowmem_adj[i]; 239 oom_score_adj = lowmem_oom_adj_to_oom_score_adj(oom_adj); 240 lowmem_adj[i] = oom_score_adj; 241 lowmem_print(1, "oom_adj %d => oom_score_adj %d\n", 242 oom_adj, oom_score_adj); 243 } 244} 245 246static int lowmem_adj_array_set(const char *val, const struct kernel_param *kp) 247{ 248 int ret; 249 250 ret = param_array_ops.set(val, kp); 251 252 /* HACK: Autodetect oom_adj values in lowmem_adj array */ 253 lowmem_autodetect_oom_adj_values(); 254 255 return ret; 256} 257 258static int lowmem_adj_array_get(char *buffer, const struct kernel_param *kp) 259{ 260 return param_array_ops.get(buffer, kp); 261} 262 263static void lowmem_adj_array_free(void *arg) 264{ 265 param_array_ops.free(arg); 266} 267 268static struct kernel_param_ops lowmem_adj_array_ops = { 269 .set = lowmem_adj_array_set, 270 .get = lowmem_adj_array_get, 271 .free = lowmem_adj_array_free, 272}; 273 274static const struct kparam_array __param_arr_adj = { 275 .max = ARRAY_SIZE(lowmem_adj), 276 .num = &lowmem_adj_size, 277 .ops = ¶m_ops_short, 278 .elemsize = sizeof(lowmem_adj[0]), 279 .elem = lowmem_adj, 280}; 281#endif 282 283module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR); 284#ifdef CONFIG_ANDROID_LOW_MEMORY_KILLER_AUTODETECT_OOM_ADJ_VALUES 285module_param_cb(adj, &lowmem_adj_array_ops, 286 .arr = &__param_arr_adj, S_IRUGO | S_IWUSR); 287__MODULE_PARM_TYPE(adj, "array of short"); 288#else 289module_param_array_named(adj, lowmem_adj, short, &lowmem_adj_size, 290 S_IRUGO | S_IWUSR); 291#endif 292module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size, 293 S_IRUGO | S_IWUSR); 294module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR); 295 296module_init(lowmem_init); 297module_exit(lowmem_exit); 298 299MODULE_LICENSE("GPL"); 300 301