b91e4bc332a77c2e6ea1219e99f92c5ee924c418
[linux-3.10.git] / drivers / staging / android / lowmemorykiller.c
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 #include <linux/module.h>
34 #include <linux/kernel.h>
35 #include <linux/mm.h>
36 #include <linux/oom.h>
37 #include <linux/sched.h>
38 #include <linux/rcupdate.h>
39 #include <linux/profile.h>
40 #include <linux/notifier.h>
41
42 static uint32_t lowmem_debug_level = 2;
43 static int lowmem_adj[6] = {
44         0,
45         1,
46         6,
47         12,
48 };
49 static int lowmem_adj_size = 4;
50 static int lowmem_minfree[6] = {
51         3 * 512,        /* 6MB */
52         2 * 1024,       /* 8MB */
53         4 * 1024,       /* 16MB */
54         16 * 1024,      /* 64MB */
55 };
56 static int lowmem_minfree_size = 4;
57
58 static unsigned long lowmem_deathpending_timeout;
59
60 #define lowmem_print(level, x...)                       \
61         do {                                            \
62                 if (lowmem_debug_level >= (level))      \
63                         printk(x);                      \
64         } while (0)
65
66 static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
67 {
68         struct task_struct *tsk;
69         struct task_struct *selected = NULL;
70         int rem = 0;
71         int tasksize;
72         int i;
73         int min_score_adj = OOM_SCORE_ADJ_MAX + 1;
74         int selected_tasksize = 0;
75         int selected_oom_score_adj;
76         int array_size = ARRAY_SIZE(lowmem_adj);
77         int other_free = global_page_state(NR_FREE_PAGES);
78         int other_file = global_page_state(NR_FILE_PAGES) -
79                                                 global_page_state(NR_SHMEM);
80
81         if (lowmem_adj_size < array_size)
82                 array_size = lowmem_adj_size;
83         if (lowmem_minfree_size < array_size)
84                 array_size = lowmem_minfree_size;
85         for (i = 0; i < array_size; i++) {
86                 if (other_free < lowmem_minfree[i] &&
87                     other_file < lowmem_minfree[i]) {
88                         min_score_adj = lowmem_adj[i];
89                         break;
90                 }
91         }
92         if (sc->nr_to_scan > 0)
93                 lowmem_print(3, "lowmem_shrink %lu, %x, ofree %d %d, ma %d\n",
94                                 sc->nr_to_scan, sc->gfp_mask, other_free,
95                                 other_file, min_score_adj);
96         rem = global_page_state(NR_ACTIVE_ANON) +
97                 global_page_state(NR_ACTIVE_FILE) +
98                 global_page_state(NR_INACTIVE_ANON) +
99                 global_page_state(NR_INACTIVE_FILE);
100         if (sc->nr_to_scan <= 0 || min_score_adj == OOM_SCORE_ADJ_MAX + 1) {
101                 lowmem_print(5, "lowmem_shrink %lu, %x, return %d\n",
102                              sc->nr_to_scan, sc->gfp_mask, rem);
103                 return rem;
104         }
105         selected_oom_score_adj = min_score_adj;
106
107         rcu_read_lock();
108         for_each_process(tsk) {
109                 struct task_struct *p;
110                 int oom_score_adj;
111
112                 if (tsk->flags & PF_KTHREAD)
113                         continue;
114
115                 p = find_lock_task_mm(tsk);
116                 if (!p)
117                         continue;
118
119                 if (test_tsk_thread_flag(p, TIF_MEMDIE) &&
120                     time_before_eq(jiffies, lowmem_deathpending_timeout)) {
121                         task_unlock(p);
122                         rcu_read_unlock();
123                         return 0;
124                 }
125                 oom_score_adj = p->signal->oom_score_adj;
126                 if (oom_score_adj < min_score_adj) {
127                         task_unlock(p);
128                         continue;
129                 }
130                 tasksize = get_mm_rss(p->mm);
131                 task_unlock(p);
132                 if (tasksize <= 0)
133                         continue;
134                 if (selected) {
135                         if (oom_score_adj < selected_oom_score_adj)
136                                 continue;
137                         if (oom_score_adj == selected_oom_score_adj &&
138                             tasksize <= selected_tasksize)
139                                 continue;
140                 }
141                 selected = p;
142                 selected_tasksize = tasksize;
143                 selected_oom_score_adj = oom_score_adj;
144                 lowmem_print(2, "select %d (%s), adj %d, size %d, to kill\n",
145                              p->pid, p->comm, oom_score_adj, tasksize);
146         }
147         if (selected) {
148                 lowmem_print(1, "send sigkill to %d (%s), adj %d, size %d\n",
149                              selected->pid, selected->comm,
150                              selected_oom_score_adj, selected_tasksize);
151                 lowmem_deathpending_timeout = jiffies + HZ;
152                 send_sig(SIGKILL, selected, 0);
153                 set_tsk_thread_flag(selected, TIF_MEMDIE);
154                 rem -= selected_tasksize;
155         }
156         lowmem_print(4, "lowmem_shrink %lu, %x, return %d\n",
157                      sc->nr_to_scan, sc->gfp_mask, rem);
158         rcu_read_unlock();
159         return rem;
160 }
161
162 static struct shrinker lowmem_shrinker = {
163         .shrink = lowmem_shrink,
164         .seeks = DEFAULT_SEEKS * 16
165 };
166
167 static int __init lowmem_init(void)
168 {
169         register_shrinker(&lowmem_shrinker);
170         return 0;
171 }
172
173 static void __exit lowmem_exit(void)
174 {
175         unregister_shrinker(&lowmem_shrinker);
176 }
177
178 module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR);
179 module_param_array_named(adj, lowmem_adj, int, &lowmem_adj_size,
180                          S_IRUGO | S_IWUSR);
181 module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
182                          S_IRUGO | S_IWUSR);
183 module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR);
184
185 module_init(lowmem_init);
186 module_exit(lowmem_exit);
187
188 MODULE_LICENSE("GPL");
189