/* drivers/misc/lowmemorykiller.c * * The lowmemorykiller driver lets user-space specify a set of memory thresholds * where processes with a range of oom_score_adj values will get killed. Specify * the minimum oom_score_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_score_adj value of 8 or higher when the free memory * drops below 4096 pages and kill processes with a oom_score_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. * */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include #include #include #include #include #include #include #include static uint32_t lowmem_debug_level = 1; static short lowmem_adj[6] = { 0, 1, 6, 12, }; static int lowmem_adj_size = 4; static int lowmem_minfree[6] = { 3 * 512, /* 6MB */ 2 * 1024, /* 8MB */ 4 * 1024, /* 16MB */ 16 * 1024, /* 64MB */ }; static int lowmem_minfree_size = 4; static unsigned long lowmem_deathpending_timeout; #define lowmem_print(level, x...) \ do { \ if (lowmem_debug_level >= (level)) \ pr_info(x); \ } while (0) static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc) { struct task_struct *tsk; struct task_struct *selected = NULL; int rem = 0; int tasksize; int i; short min_score_adj = OOM_SCORE_ADJ_MAX + 1; int minfree = 0; int selected_tasksize = 0; short selected_oom_score_adj; int array_size = ARRAY_SIZE(lowmem_adj); int other_free = global_page_state(NR_FREE_PAGES) - totalreserve_pages; int other_file = global_page_state(NR_FILE_PAGES) - global_page_state(NR_SHMEM); 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++) { minfree = lowmem_minfree[i]; if (other_free < minfree && other_file < minfree) { min_score_adj = lowmem_adj[i]; break; } } if (sc->nr_to_scan > 0) lowmem_print(3, "lowmem_shrink %lu, %x, ofree %d %d, ma %hd\n", sc->nr_to_scan, sc->gfp_mask, other_free, other_file, min_score_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_score_adj == OOM_SCORE_ADJ_MAX + 1) { lowmem_print(5, "lowmem_shrink %lu, %x, return %d\n", sc->nr_to_scan, sc->gfp_mask, rem); return rem; } selected_oom_score_adj = min_score_adj; rcu_read_lock(); for_each_process(tsk) { struct task_struct *p; short oom_score_adj; if (tsk->flags & PF_KTHREAD) continue; p = find_lock_task_mm(tsk); if (!p) continue; if (test_tsk_thread_flag(p, TIF_MEMDIE) && time_before_eq(jiffies, lowmem_deathpending_timeout)) { task_unlock(p); rcu_read_unlock(); return 0; } oom_score_adj = p->signal->oom_score_adj; if (oom_score_adj < min_score_adj) { task_unlock(p); continue; } tasksize = get_mm_rss(p->mm); task_unlock(p); if (tasksize <= 0) continue; if (selected) { if (oom_score_adj < selected_oom_score_adj) continue; if (oom_score_adj == selected_oom_score_adj && tasksize <= selected_tasksize) continue; } selected = p; selected_tasksize = tasksize; selected_oom_score_adj = oom_score_adj; lowmem_print(2, "select '%s' (%d), adj %hd, size %d, to kill\n", p->comm, p->pid, oom_score_adj, tasksize); } if (selected) { lowmem_print(1, "Killing '%s' (%d), adj %hd,\n" \ " to free %ldkB on behalf of '%s' (%d) because\n" \ " cache %ldkB is below limit %ldkB for oom_score_adj %hd\n" \ " Free memory is %ldkB above reserved\n", selected->comm, selected->pid, selected_oom_score_adj, selected_tasksize * (long)(PAGE_SIZE / 1024), current->comm, current->pid, other_file * (long)(PAGE_SIZE / 1024), minfree * (long)(PAGE_SIZE / 1024), min_score_adj, other_free * (long)(PAGE_SIZE / 1024)); lowmem_deathpending_timeout = jiffies + HZ; send_sig(SIGKILL, selected, 0); set_tsk_thread_flag(selected, TIF_MEMDIE); rem -= selected_tasksize; } lowmem_print(4, "lowmem_shrink %lu, %x, return %d\n", sc->nr_to_scan, sc->gfp_mask, rem); rcu_read_unlock(); return rem; } static struct shrinker lowmem_shrinker = { .shrink = lowmem_shrink, .seeks = DEFAULT_SEEKS * 16 }; static int __init lowmem_init(void) { register_shrinker(&lowmem_shrinker); return 0; } static void __exit lowmem_exit(void) { unregister_shrinker(&lowmem_shrinker); } #ifdef CONFIG_ANDROID_LOW_MEMORY_KILLER_AUTODETECT_OOM_ADJ_VALUES static short lowmem_oom_adj_to_oom_score_adj(short oom_adj) { if (oom_adj == OOM_ADJUST_MAX) return OOM_SCORE_ADJ_MAX; else return (oom_adj * OOM_SCORE_ADJ_MAX) / -OOM_DISABLE; } static void lowmem_autodetect_oom_adj_values(void) { int i; short oom_adj; short oom_score_adj; int array_size = ARRAY_SIZE(lowmem_adj); if (lowmem_adj_size < array_size) array_size = lowmem_adj_size; if (array_size <= 0) return; oom_adj = lowmem_adj[array_size - 1]; if (oom_adj > OOM_ADJUST_MAX) return; oom_score_adj = lowmem_oom_adj_to_oom_score_adj(oom_adj); if (oom_score_adj <= OOM_ADJUST_MAX) return; lowmem_print(1, "lowmem_shrink: convert oom_adj to oom_score_adj:\n"); for (i = 0; i < array_size; i++) { oom_adj = lowmem_adj[i]; oom_score_adj = lowmem_oom_adj_to_oom_score_adj(oom_adj); lowmem_adj[i] = oom_score_adj; lowmem_print(1, "oom_adj %d => oom_score_adj %d\n", oom_adj, oom_score_adj); } } static int lowmem_adj_array_set(const char *val, const struct kernel_param *kp) { int ret; ret = param_array_ops.set(val, kp); /* HACK: Autodetect oom_adj values in lowmem_adj array */ lowmem_autodetect_oom_adj_values(); return ret; } static int lowmem_adj_array_get(char *buffer, const struct kernel_param *kp) { return param_array_ops.get(buffer, kp); } static void lowmem_adj_array_free(void *arg) { param_array_ops.free(arg); } static struct kernel_param_ops lowmem_adj_array_ops = { .set = lowmem_adj_array_set, .get = lowmem_adj_array_get, .free = lowmem_adj_array_free, }; static const struct kparam_array __param_arr_adj = { .max = ARRAY_SIZE(lowmem_adj), .num = &lowmem_adj_size, .ops = ¶m_ops_short, .elemsize = sizeof(lowmem_adj[0]), .elem = lowmem_adj, }; #endif module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR); #ifdef CONFIG_ANDROID_LOW_MEMORY_KILLER_AUTODETECT_OOM_ADJ_VALUES __module_param_call(MODULE_PARAM_PREFIX, adj, &lowmem_adj_array_ops, .arr = &__param_arr_adj, S_IRUGO | S_IWUSR, -1); __MODULE_PARM_TYPE(adj, "array of short"); #else module_param_array_named(adj, lowmem_adj, short, &lowmem_adj_size, S_IRUGO | S_IWUSR); #endif 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");