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
47 static uint32_t lowmem_debug_level = 1;
48 static short lowmem_adj[6] = {
49 0,
50 1,
51 6,
52 12,
53 };
54 static int lowmem_adj_size = 4;
55 static int lowmem_minfree[6] = {
56 3 * 512, /* 6MB */
57 2 * 1024, /* 8MB */
58 4 * 1024, /* 16MB */
59 16 * 1024, /* 64MB */
60 };
61 static int lowmem_minfree_size = 4;
62
63 static 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
lowmem_count(struct shrinker * s,struct shrink_control * sc)71 static 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
lowmem_scan(struct shrinker * s,struct shrink_control * sc)80 static 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 global_page_state(NR_UNEVICTABLE) -
96 total_swapcache_pages();
97
98 if (lowmem_adj_size < array_size)
99 array_size = lowmem_adj_size;
100 if (lowmem_minfree_size < array_size)
101 array_size = lowmem_minfree_size;
102 for (i = 0; i < array_size; i++) {
103 minfree = lowmem_minfree[i];
104 if (other_free < minfree && other_file < minfree) {
105 min_score_adj = lowmem_adj[i];
106 break;
107 }
108 }
109
110 lowmem_print(3, "lowmem_scan %lu, %x, ofree %d %d, ma %hd\n",
111 sc->nr_to_scan, sc->gfp_mask, other_free,
112 other_file, min_score_adj);
113
114 if (min_score_adj == OOM_SCORE_ADJ_MAX + 1) {
115 lowmem_print(5, "lowmem_scan %lu, %x, return 0\n",
116 sc->nr_to_scan, sc->gfp_mask);
117 return 0;
118 }
119
120 selected_oom_score_adj = min_score_adj;
121
122 rcu_read_lock();
123 for_each_process(tsk) {
124 struct task_struct *p;
125 short oom_score_adj;
126
127 if (tsk->flags & PF_KTHREAD)
128 continue;
129
130 p = find_lock_task_mm(tsk);
131 if (!p)
132 continue;
133
134 if (test_tsk_thread_flag(p, TIF_MEMDIE) &&
135 time_before_eq(jiffies, lowmem_deathpending_timeout)) {
136 task_unlock(p);
137 rcu_read_unlock();
138 return 0;
139 }
140 oom_score_adj = p->signal->oom_score_adj;
141 if (oom_score_adj < min_score_adj) {
142 task_unlock(p);
143 continue;
144 }
145 tasksize = get_mm_rss(p->mm);
146 task_unlock(p);
147 if (tasksize <= 0)
148 continue;
149 if (selected) {
150 if (oom_score_adj < selected_oom_score_adj)
151 continue;
152 if (oom_score_adj == selected_oom_score_adj &&
153 tasksize <= selected_tasksize)
154 continue;
155 }
156 selected = p;
157 selected_tasksize = tasksize;
158 selected_oom_score_adj = oom_score_adj;
159 lowmem_print(2, "select '%s' (%d), adj %hd, size %d, to kill\n",
160 p->comm, p->pid, oom_score_adj, tasksize);
161 }
162 if (selected) {
163 long cache_size = other_file * (long)(PAGE_SIZE / 1024);
164 long cache_limit = minfree * (long)(PAGE_SIZE / 1024);
165 long free = other_free * (long)(PAGE_SIZE / 1024);
166 trace_lowmemory_kill(selected, cache_size, cache_limit, free);
167 lowmem_print(1, "Killing '%s' (%d), adj %hd,\n" \
168 " to free %ldkB on behalf of '%s' (%d) because\n" \
169 " cache %ldkB is below limit %ldkB for oom_score_adj %hd\n" \
170 " Free memory is %ldkB above reserved\n",
171 selected->comm, selected->pid,
172 selected_oom_score_adj,
173 selected_tasksize * (long)(PAGE_SIZE / 1024),
174 current->comm, current->pid,
175 cache_size, cache_limit,
176 min_score_adj,
177 free);
178 lowmem_deathpending_timeout = jiffies + HZ;
179 set_tsk_thread_flag(selected, TIF_MEMDIE);
180 send_sig(SIGKILL, selected, 0);
181 rem += selected_tasksize;
182 }
183
184 lowmem_print(4, "lowmem_scan %lu, %x, return %lu\n",
185 sc->nr_to_scan, sc->gfp_mask, rem);
186 rcu_read_unlock();
187 return rem;
188 }
189
190 static struct shrinker lowmem_shrinker = {
191 .scan_objects = lowmem_scan,
192 .count_objects = lowmem_count,
193 .seeks = DEFAULT_SEEKS * 16
194 };
195
lowmem_init(void)196 static int __init lowmem_init(void)
197 {
198 register_shrinker(&lowmem_shrinker);
199 return 0;
200 }
201
lowmem_exit(void)202 static void __exit lowmem_exit(void)
203 {
204 unregister_shrinker(&lowmem_shrinker);
205 }
206
207 #ifdef CONFIG_ANDROID_LOW_MEMORY_KILLER_AUTODETECT_OOM_ADJ_VALUES
lowmem_oom_adj_to_oom_score_adj(short oom_adj)208 static short lowmem_oom_adj_to_oom_score_adj(short oom_adj)
209 {
210 if (oom_adj == OOM_ADJUST_MAX)
211 return OOM_SCORE_ADJ_MAX;
212 else
213 return (oom_adj * OOM_SCORE_ADJ_MAX) / -OOM_DISABLE;
214 }
215
lowmem_autodetect_oom_adj_values(void)216 static void lowmem_autodetect_oom_adj_values(void)
217 {
218 int i;
219 short oom_adj;
220 short oom_score_adj;
221 int array_size = ARRAY_SIZE(lowmem_adj);
222
223 if (lowmem_adj_size < array_size)
224 array_size = lowmem_adj_size;
225
226 if (array_size <= 0)
227 return;
228
229 oom_adj = lowmem_adj[array_size - 1];
230 if (oom_adj > OOM_ADJUST_MAX)
231 return;
232
233 oom_score_adj = lowmem_oom_adj_to_oom_score_adj(oom_adj);
234 if (oom_score_adj <= OOM_ADJUST_MAX)
235 return;
236
237 lowmem_print(1, "lowmem_shrink: convert oom_adj to oom_score_adj:\n");
238 for (i = 0; i < array_size; i++) {
239 oom_adj = lowmem_adj[i];
240 oom_score_adj = lowmem_oom_adj_to_oom_score_adj(oom_adj);
241 lowmem_adj[i] = oom_score_adj;
242 lowmem_print(1, "oom_adj %d => oom_score_adj %d\n",
243 oom_adj, oom_score_adj);
244 }
245 }
246
lowmem_adj_array_set(const char * val,const struct kernel_param * kp)247 static int lowmem_adj_array_set(const char *val, const struct kernel_param *kp)
248 {
249 int ret;
250
251 ret = param_array_ops.set(val, kp);
252
253 /* HACK: Autodetect oom_adj values in lowmem_adj array */
254 lowmem_autodetect_oom_adj_values();
255
256 return ret;
257 }
258
lowmem_adj_array_get(char * buffer,const struct kernel_param * kp)259 static int lowmem_adj_array_get(char *buffer, const struct kernel_param *kp)
260 {
261 return param_array_ops.get(buffer, kp);
262 }
263
lowmem_adj_array_free(void * arg)264 static void lowmem_adj_array_free(void *arg)
265 {
266 param_array_ops.free(arg);
267 }
268
269 static struct kernel_param_ops lowmem_adj_array_ops = {
270 .set = lowmem_adj_array_set,
271 .get = lowmem_adj_array_get,
272 .free = lowmem_adj_array_free,
273 };
274
275 static const struct kparam_array __param_arr_adj = {
276 .max = ARRAY_SIZE(lowmem_adj),
277 .num = &lowmem_adj_size,
278 .ops = ¶m_ops_short,
279 .elemsize = sizeof(lowmem_adj[0]),
280 .elem = lowmem_adj,
281 };
282 #endif
283
284 module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR);
285 #ifdef CONFIG_ANDROID_LOW_MEMORY_KILLER_AUTODETECT_OOM_ADJ_VALUES
286 module_param_cb(adj, &lowmem_adj_array_ops,
287 .arr = &__param_arr_adj, S_IRUGO | S_IWUSR);
288 __MODULE_PARM_TYPE(adj, "array of short");
289 #else
290 module_param_array_named(adj, lowmem_adj, short, &lowmem_adj_size,
291 S_IRUGO | S_IWUSR);
292 #endif
293 module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
294 S_IRUGO | S_IWUSR);
295 module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR);
296
297 module_init(lowmem_init);
298 module_exit(lowmem_exit);
299
300 MODULE_LICENSE("GPL");
301
302