lowmemorykiller.c revision ae57804a6aae5fbbc5faf8cd572dcc1fff494607
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 190module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR); 191module_param_array_named(adj, lowmem_adj, short, &lowmem_adj_size, 192 S_IRUGO | S_IWUSR); 193module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size, 194 S_IRUGO | S_IWUSR); 195module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR); 196 197module_init(lowmem_init); 198module_exit(lowmem_exit); 199 200MODULE_LICENSE("GPL"); 201 202