| /* 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. |
| * |
| */ |
| |
| #include <linux/module.h> |
| #include <linux/kernel.h> |
| #include <linux/mm.h> |
| #include <linux/oom.h> |
| #include <linux/sched.h> |
| #include <linux/rcupdate.h> |
| #include <linux/notifier.h> |
| |
| static uint32_t lowmem_debug_level = 2; |
| static int 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)) \ |
| printk(x); \ |
| } while (0) |
| |
| static int test_task_flag(struct task_struct *p, int flag) |
| { |
| struct task_struct *t = p; |
| |
| do { |
| task_lock(t); |
| if (test_tsk_thread_flag(t, flag)) { |
| task_unlock(t); |
| return 1; |
| } |
| task_unlock(t); |
| } while_each_thread(p, t); |
| |
| return 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; |
| int min_score_adj = OOM_SCORE_ADJ_MAX + 1; |
| int selected_tasksize = 0; |
| int selected_oom_score_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 (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_score_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_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; |
| int oom_score_adj; |
| |
| if (tsk->flags & PF_KTHREAD) |
| continue; |
| |
| if (time_before_eq(jiffies, lowmem_deathpending_timeout)) { |
| if (test_task_flag(tsk, TIF_MEMDIE)) { |
| rcu_read_unlock(); |
| return 0; |
| } |
| } |
| |
| p = find_lock_task_mm(tsk); |
| if (!p) |
| continue; |
| |
| 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 %d (%s), adj %d, size %d, to kill\n", |
| p->pid, p->comm, oom_score_adj, tasksize); |
| } |
| if (selected) { |
| lowmem_print(1, "send sigkill to %d (%s), adj %d, size %d\n", |
| selected->pid, selected->comm, |
| selected_oom_score_adj, selected_tasksize); |
| 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 int lowmem_oom_adj_to_oom_score_adj(int 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; |
| int oom_adj; |
| int 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_int, |
| .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 int"); |
| #else |
| module_param_array_named(adj, lowmem_adj, int, &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"); |
| |