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_adj values will get killed. Specify the
   5  * minimum oom_adj values in /sys/module/lowmemorykiller/parameters/adj and the
   6  * number of free pages in /sys/module/lowmemorykiller/parameters/minfree. Both
   7  * files take a comma separated list of numbers in ascending order.
   8  *
   9  * For example, write "0,8" to /sys/module/lowmemorykiller/parameters/adj and
  10  * "1024,4096" to /sys/module/lowmemorykiller/parameters/minfree to kill
  11  * processes with a oom_adj value of 8 or higher when the free memory drops
  12  * below 4096 pages and kill processes with a oom_adj value of 0 or higher
  13  * when the free memory drops below 1024 pages.
  14  *
  15  * The driver considers memory used for caches to be free, but if a large
  16  * percentage of the cached memory is locked this can be very inaccurate
  17  * and processes may not get killed until the normal oom killer is triggered.
  18  *
  19  * Copyright (C) 2007-2008 Google, Inc.
  20  *
  21  * This software is licensed under the terms of the GNU General Public
  22  * License version 2, as published by the Free Software Foundation, and
  23  * may be copied, distributed, and modified under those terms.
  24  *
  25  * This program is distributed in the hope that it will be useful,
  26  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  27  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  28  * GNU General Public License for more details.
  29  *
  30  */
  31
  32 #include <linux/module.h>
  33 #include <linux/kernel.h>
  34 #include <linux/mm.h>
  35 #include <linux/oom.h>
  36 #include <linux/sched.h>
  37 #include <linux/profile.h>
  38 #include <linux/notifier.h>
  39
  40 static uint32_t lowmem_debug_level = 2;
  41 static int lowmem_adj[6] = {
  42         0,
  43         1,
  44         6,
  45         12,
  46 };
  47 static int lowmem_adj_size = 4;
  48 static size_t lowmem_minfree[6] = {
  49         3 * 512,        /* 6MB */
  50         2 * 1024,       /* 8MB */
  51         4 * 1024,       /* 16MB */
  52         16 * 1024,      /* 64MB */
  53 };
  54 static int lowmem_minfree_size = 4;
  55
  56 static struct task_struct *lowmem_deathpending;
  57
  58 #define lowmem_print(level, x...)                       \
  59         do {                                            \
  60                 if (lowmem_debug_level >= (level))      \
  61                         printk(x);                      \
  62         } while (0)
  63
  64 static int
  65 task_notify_func(struct notifier_block *self, unsigned long val, void *data);
  66
  67 static struct notifier_block task_nb = {
  68         .notifier_call  = task_notify_func,
  69 };
  70
  71 static int
  72 task_notify_func(struct notifier_block *self, unsigned long val, void *data)
  73 {
  74         struct task_struct *task = data;
  75         if (task == lowmem_deathpending) {
  76                 lowmem_deathpending = NULL;
  77                 task_handoff_unregister(&task_nb);
  78         }
  79         return NOTIFY_OK;
  80 }
  81
  82 static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
  83 {
  84         struct task_struct *p;
  85         struct task_struct *selected = NULL;
  86         int rem = 0;
  87         int tasksize;
  88         int i;
  89         int min_adj = OOM_ADJUST_MAX + 1;
  90         int selected_tasksize = 0;
  91         int selected_oom_adj;
  92         int array_size = ARRAY_SIZE(lowmem_adj);
  93         int other_free = global_page_state(NR_FREE_PAGES);
  94         int other_file = global_page_state(NR_FILE_PAGES) -
  95                                                 global_page_state(NR_SHMEM);
  96
  97         /*
  98          * If we already have a death outstanding, then
  99          * bail out right away; indicating to vmscan
 100          * that we have nothing further to offer on
 101          * this pass.
 102          *
 103          * Note: Currently you need CONFIG_PROFILING
 104          * for this to work correctly.
 105          */
 106         if (lowmem_deathpending)
 107                 return 0;
 108
 109         if (lowmem_adj_size < array_size)
 110                 array_size = lowmem_adj_size;
 111         if (lowmem_minfree_size < array_size)
 112                 array_size = lowmem_minfree_size;
 113         for (i = 0; i < array_size; i++) {
 114                 if (other_free < lowmem_minfree[i] &&
 115                     other_file < lowmem_minfree[i]) {
 116                         min_adj = lowmem_adj[i];
 117                         break;
 118                 }
 119         }
 120         if (sc->nr_to_scan > 0)
 121                 lowmem_print(3, "lowmem_shrink %lu, %x, ofree %d %d, ma %d\n",
 122                                 sc->nr_to_scan, sc->gfp_mask, other_free,
 123                                 other_file, min_adj);
 124         rem = global_page_state(NR_ACTIVE_ANON) +
 125                 global_page_state(NR_ACTIVE_FILE) +
 126                 global_page_state(NR_INACTIVE_ANON) +
 127                 global_page_state(NR_INACTIVE_FILE);
 128         if (sc->nr_to_scan <= 0 || min_adj == OOM_ADJUST_MAX + 1) {
 129                 lowmem_print(5, "lowmem_shrink %lu, %x, return %d\n",
 130                              sc->nr_to_scan, sc->gfp_mask, rem);
 131                 return rem;
 132         }
 133         selected_oom_adj = min_adj;
 134
 135         read_lock(&tasklist_lock);
 136         for_each_process(p) {
 137                 struct mm_struct *mm;
 138                 struct signal_struct *sig;
 139                 int oom_adj;
 140
 141                 task_lock(p);
 142                 mm = p->mm;
 143                 sig = p->signal;
 144                 if (!mm || !sig) {
 145                         task_unlock(p);
 146                         continue;
 147                 }
 148                 oom_adj = sig->oom_adj;
 149                 if (oom_adj < min_adj) {
 150                         task_unlock(p);
 151                         continue;
 152                 }
 153                 tasksize = get_mm_rss(mm);
 154                 task_unlock(p);
 155                 if (tasksize <= 0)
 156                         continue;
 157                 if (selected) {
 158                         if (oom_adj < selected_oom_adj)
 159                                 continue;
 160                         if (oom_adj == selected_oom_adj &&
 161                             tasksize <= selected_tasksize)
 162                                 continue;
 163                 }
 164                 selected = p;
 165                 selected_tasksize = tasksize;
 166                 selected_oom_adj = oom_adj;
 167                 lowmem_print(2, "select %d (%s), adj %d, size %d, to kill\n",
 168                              p->pid, p->comm, oom_adj, tasksize);
 169         }
 170         if (selected) {
 171                 lowmem_print(1, "send sigkill to %d (%s), adj %d, size %d\n",
 172                              selected->pid, selected->comm,
 173                              selected_oom_adj, selected_tasksize);
 174                 /*
 175                  * If CONFIG_PROFILING is off, then task_handoff_register()
 176                  * is a nop. In that case we don't want to stall the killer
 177                  * by setting lowmem_deathpending.
 178                  */
 179 #ifdef CONFIG_PROFILING
 180                 lowmem_deathpending = selected;
 181                 task_handoff_register(&task_nb);
 182 #endif
 183                 force_sig(SIGKILL, selected);
 184                 rem -= selected_tasksize;
 185         }
 186         lowmem_print(4, "lowmem_shrink %lu, %x, return %d\n",
 187                      sc->nr_to_scan, sc->gfp_mask, rem);
 188         read_unlock(&tasklist_lock);
 189         return rem;
 190 }
 191
 192 static struct shrinker lowmem_shrinker = {
 193         .shrink = lowmem_shrink,
 194         .seeks = DEFAULT_SEEKS * 16
 195 };
 196
 197 static int __init lowmem_init(void)
 198 {
 199         register_shrinker(&lowmem_shrinker);
 200         return 0;
 201 }
 202
 203 static void __exit lowmem_exit(void)
 204 {
 205         unregister_shrinker(&lowmem_shrinker);
 206 }
 207
 208 module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR);
 209 module_param_array_named(adj, lowmem_adj, int, &lowmem_adj_size,
 210                          S_IRUGO | S_IWUSR);
 211 module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
 212                          S_IRUGO | S_IWUSR);
 213 module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR);
 214
 215 module_init(lowmem_init);
 216 module_exit(lowmem_exit);
 217
 218 MODULE_LICENSE("GPL");
 219