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 struct task_struct *lowmem_deathpending;
  59 static unsigned long lowmem_deathpending_timeout;
  60
  61 #define lowmem_print(level, x...)                       \
  62         do {                                            \
  63                 if (lowmem_debug_level >= (level))      \
  64                         printk(x);                      \
  65         } while (0)
  66
  67 static int
  68 task_notify_func(struct notifier_block *self, unsigned long val, void *data);
  69
  70 static struct notifier_block task_nb = {
  71         .notifier_call  = task_notify_func,
  72 };
  73
  74 static int
  75 task_notify_func(struct notifier_block *self, unsigned long val, void *data)
  76 {
  77         struct task_struct *task = data;
  78
  79         if (task == lowmem_deathpending)
  80                 lowmem_deathpending = NULL;
  81
  82         return NOTIFY_OK;
  83 }
  84
  85 static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
  86 {
  87         struct task_struct *tsk;
  88         struct task_struct *selected = NULL;
  89         int rem = 0;
  90         int tasksize;
  91         int i;
  92         int min_score_adj = OOM_SCORE_ADJ_MAX + 1;
  93         int selected_tasksize = 0;
  94         int selected_oom_score_adj;
  95         int array_size = ARRAY_SIZE(lowmem_adj);
  96         int other_free = global_page_state(NR_FREE_PAGES);
  97         int other_file = global_page_state(NR_FILE_PAGES) -
  98                                                 global_page_state(NR_SHMEM);
  99
 100         /*
 101          * If we already have a death outstanding, then
 102          * bail out right away; indicating to vmscan
 103          * that we have nothing further to offer on
 104          * this pass.
 105          *
 106          * Note: Currently you need CONFIG_PROFILING
 107          * for this to work correctly.
 108          */
 109         if (lowmem_deathpending &&
 110             time_before_eq(jiffies, lowmem_deathpending_timeout))
 111                 return 0;
 112
 113         if (lowmem_adj_size < array_size)
 114                 array_size = lowmem_adj_size;
 115         if (lowmem_minfree_size < array_size)
 116                 array_size = lowmem_minfree_size;
 117         for (i = 0; i < array_size; i++) {
 118                 if (other_free < lowmem_minfree[i] &&
 119                     other_file < lowmem_minfree[i]) {
 120                         min_score_adj = lowmem_adj[i];
 121                         break;
 122                 }
 123         }
 124         if (sc->nr_to_scan > 0)
 125                 lowmem_print(3, "lowmem_shrink %lu, %x, ofree %d %d, ma %d\n",
 126                                 sc->nr_to_scan, sc->gfp_mask, other_free,
 127                                 other_file, min_score_adj);
 128         rem = global_page_state(NR_ACTIVE_ANON) +
 129                 global_page_state(NR_ACTIVE_FILE) +
 130                 global_page_state(NR_INACTIVE_ANON) +
 131                 global_page_state(NR_INACTIVE_FILE);
 132         if (sc->nr_to_scan <= 0 || min_score_adj == OOM_SCORE_ADJ_MAX + 1) {
 133                 lowmem_print(5, "lowmem_shrink %lu, %x, return %d\n",
 134                              sc->nr_to_scan, sc->gfp_mask, rem);
 135                 return rem;
 136         }
 137         selected_oom_score_adj = min_score_adj;
 138
 139         rcu_read_lock();
 140         for_each_process(tsk) {
 141                 struct task_struct *p;
 142                 int oom_score_adj;
 143
 144                 if (tsk->flags & PF_KTHREAD)
 145                         continue;
 146
 147                 p = find_lock_task_mm(tsk);
 148                 if (!p)
 149                         continue;
 150
 151                 oom_score_adj = p->signal->oom_score_adj;
 152                 if (oom_score_adj < min_score_adj) {
 153                         task_unlock(p);
 154                         continue;
 155                 }
 156                 tasksize = get_mm_rss(p->mm);
 157                 task_unlock(p);
 158                 if (tasksize <= 0)
 159                         continue;
 160                 if (selected) {
 161                         if (oom_score_adj < selected_oom_score_adj)
 162                                 continue;
 163                         if (oom_score_adj == selected_oom_score_adj &&
 164                             tasksize <= selected_tasksize)
 165                                 continue;
 166                 }
 167                 selected = p;
 168                 selected_tasksize = tasksize;
 169                 selected_oom_score_adj = oom_score_adj;
 170                 lowmem_print(2, "select %d (%s), adj %d, size %d, to kill\n",
 171                              p->pid, p->comm, oom_score_adj, tasksize);
 172         }
 173         if (selected) {
 174                 lowmem_print(1, "send sigkill to %d (%s), adj %d, size %d\n",
 175                              selected->pid, selected->comm,
 176                              selected_oom_score_adj, selected_tasksize);
 177                 /*
 178                  * If CONFIG_PROFILING is off, then we don't want to stall
 179                  * the killer by setting lowmem_deathpending.
 180                  */
 181 #ifdef CONFIG_PROFILING
 182                 lowmem_deathpending = selected;
 183                 lowmem_deathpending_timeout = jiffies + HZ;
 184 #endif
 185                 send_sig(SIGKILL, selected, 0);
 186                 rem -= selected_tasksize;
 187         }
 188         lowmem_print(4, "lowmem_shrink %lu, %x, return %d\n",
 189                      sc->nr_to_scan, sc->gfp_mask, rem);
 190         rcu_read_unlock();
 191         return rem;
 192 }
 193
 194 static struct shrinker lowmem_shrinker = {
 195         .shrink = lowmem_shrink,
 196         .seeks = DEFAULT_SEEKS * 16
 197 };
 198
 199 static int __init lowmem_init(void)
 200 {
 201         task_handoff_register(&task_nb);
 202         register_shrinker(&lowmem_shrinker);
 203         return 0;
 204 }
 205
 206 static void __exit lowmem_exit(void)
 207 {
 208         unregister_shrinker(&lowmem_shrinker);
 209         task_handoff_unregister(&task_nb);
 210 }
 211
 212 module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR);
 213 module_param_array_named(adj, lowmem_adj, int, &lowmem_adj_size,
 214                          S_IRUGO | S_IWUSR);
 215 module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
 216                          S_IRUGO | S_IWUSR);
 217 module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR);
 218
 219 module_init(lowmem_init);
 220 module_exit(lowmem_exit);
 221
 222 MODULE_LICENSE("GPL");
 223