/* drivers/misc/lowmemorykiller.c * * The lowmemorykiller driver lets user-space specify a set of memory thresholds * where processes with a range of oom_adj values will get killed. Specify the * minimum oom_adj values in /sys/module/lowmemorykiller/parameters/adj and the * number of free pages in /sys/module/lowmemorykiller/parameters/minfree. Both * files take a comma separated list of numbers in ascending order. * * For example, write "0,8" to /sys/module/lowmemorykiller/parameters/adj and * "1024,4096" to /sys/module/lowmemorykiller/parameters/minfree to kill processes * with a oom_adj value of 8 or higher when the free memory drops below 4096 pages * and kill processes with a oom_adj value of 0 or higher when the free memory * drops below 1024 pages. * * The driver considers memory used for caches to be free, but if a large * percentage of the cached memory is locked this can be very inaccurate * and processes may not get killed until the normal oom killer is triggered. * * Copyright (C) 2007-2008 Google, Inc. * * This software is licensed under the terms of the GNU General Public * License version 2, as published by the Free Software Foundation, and * may be copied, distributed, and modified under those terms. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * */ #include #include #include #include #include #include static uint32_t lowmem_debug_level = 2; static int lowmem_adj[6] = { 0, 1, 6, 12, }; static int lowmem_adj_size = 4; static size_t lowmem_minfree[6] = { 3 * 512, /* 6MB */ 2 * 1024, /* 8MB */ 4 * 1024, /* 16MB */ 16 * 1024, /* 64MB */ }; static int lowmem_minfree_size = 4; static struct task_struct *lowmem_deathpending; static unsigned long lowmem_deathpending_timeout; #define lowmem_print(level, x...) \ do { \ if (lowmem_debug_level >= (level)) \ printk(x); \ } while (0) static int task_notify_func(struct notifier_block *self, unsigned long val, void *data); static struct notifier_block task_nb = { .notifier_call = task_notify_func, }; static int task_notify_func(struct notifier_block *self, unsigned long val, void *data) { struct task_struct *task = data; if (task == lowmem_deathpending) lowmem_deathpending = NULL; return NOTIFY_OK; } static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc) { struct task_struct *p; struct task_struct *selected = NULL; int rem = 0; int tasksize; int i; int min_adj = OOM_ADJUST_MAX + 1; int selected_tasksize = 0; int selected_oom_adj; int array_size = ARRAY_SIZE(lowmem_adj); int other_free = global_page_state(NR_FREE_PAGES); int other_file = global_page_state(NR_FILE_PAGES) - global_page_state(NR_SHMEM); /* * If we already have a death outstanding, then * bail out right away; indicating to vmscan * that we have nothing further to offer on * this pass. * */ if (lowmem_deathpending && time_before_eq(jiffies, lowmem_deathpending_timeout)) return 0; if (lowmem_adj_size < array_size) array_size = lowmem_adj_size; if (lowmem_minfree_size < array_size) array_size = lowmem_minfree_size; for (i = 0; i < array_size; i++) { if (other_free < lowmem_minfree[i] && other_file < lowmem_minfree[i]) { min_adj = lowmem_adj[i]; break; } } if (sc->nr_to_scan > 0) lowmem_print(3, "lowmem_shrink %lu, %x, ofree %d %d, ma %d\n", sc->nr_to_scan, sc->gfp_mask, other_free, other_file, min_adj); rem = global_page_state(NR_ACTIVE_ANON) + global_page_state(NR_ACTIVE_FILE) + global_page_state(NR_INACTIVE_ANON) + global_page_state(NR_INACTIVE_FILE); if (sc->nr_to_scan <= 0 || min_adj == OOM_ADJUST_MAX + 1) { lowmem_print(5, "lowmem_shrink %lu, %x, return %d\n", sc->nr_to_scan, sc->gfp_mask, rem); return rem; } selected_oom_adj = min_adj; read_lock(&tasklist_lock); for_each_process(p) { struct mm_struct *mm; struct signal_struct *sig; int oom_adj; task_lock(p); mm = p->mm; sig = p->signal; if (!mm || !sig) { task_unlock(p); continue; } oom_adj = sig->oom_adj; if (oom_adj < min_adj) { task_unlock(p); continue; } tasksize = get_mm_rss(mm); task_unlock(p); if (tasksize <= 0) continue; if (selected) { if (oom_adj < selected_oom_adj) continue; if (oom_adj == selected_oom_adj && tasksize <= selected_tasksize) continue; } selected = p; selected_tasksize = tasksize; selected_oom_adj = oom_adj; lowmem_print(2, "select %d (%s), adj %d, size %d, to kill\n", p->pid, p->comm, oom_adj, tasksize); } if (selected) { lowmem_print(1, "send sigkill to %d (%s), adj %d, size %d\n", selected->pid, selected->comm, selected_oom_adj, selected_tasksize); lowmem_deathpending = selected; lowmem_deathpending_timeout = jiffies + HZ; force_sig(SIGKILL, selected); rem -= selected_tasksize; } lowmem_print(4, "lowmem_shrink %lu, %x, return %d\n", sc->nr_to_scan, sc->gfp_mask, rem); read_unlock(&tasklist_lock); return rem; } static struct shrinker lowmem_shrinker = { .shrink = lowmem_shrink, .seeks = DEFAULT_SEEKS * 16 }; static int __init lowmem_init(void) { task_free_register(&task_nb); register_shrinker(&lowmem_shrinker); return 0; } static void __exit lowmem_exit(void) { unregister_shrinker(&lowmem_shrinker); task_free_unregister(&task_nb); } module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR); module_param_array_named(adj, lowmem_adj, int, &lowmem_adj_size, S_IRUGO | S_IWUSR); module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size, S_IRUGO | S_IWUSR); module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR); module_init(lowmem_init); module_exit(lowmem_exit); MODULE_LICENSE("GPL");