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 static unsigned long lowmem_deathpending_timeout;
  58
  59 #define lowmem_print(level, x...)                       \
  60         do {                                            \
  61                 if (lowmem_debug_level >= (level))      \
  62                         printk(x);                      \
  63         } while (0)
  64
  65 static int
  66 task_notify_func(struct notifier_block *self, unsigned long val, void *data);
  67
  68 static struct notifier_block task_nb = {
  69         .notifier_call  = task_notify_func,
  70 };
  71
  72 static int
  73 task_notify_func(struct notifier_block *self, unsigned long val, void *data)
  74 {
  75         struct task_struct *task = data;
  76         if (task == lowmem_deathpending) {
  77                 lowmem_deathpending = NULL;
  78                 task_handoff_unregister(&task_nb);
  79         }
  80         return NOTIFY_OK;
  81 }
  82
  83 static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
  84 {
  85         struct task_struct *p;
  86         struct task_struct *selected = NULL;
  87         int rem = 0;
  88         int tasksize;
  89         int i;
  90         int min_adj = OOM_ADJUST_MAX + 1;
  91         int selected_tasksize = 0;
  92         int selected_oom_adj;
  93         int array_size = ARRAY_SIZE(lowmem_adj);
  94         int other_free = global_page_state(NR_FREE_PAGES);
  95         int other_file = global_page_state(NR_FILE_PAGES) -
  96                                                 global_page_state(NR_SHMEM);
  97
  98         /*
  99          * If we already have a death outstanding, then
 100          * bail out right away; indicating to vmscan
 101          * that we have nothing further to offer on
 102          * this pass.
 103          *
 104          * Note: Currently you need CONFIG_PROFILING
 105          * for this to work correctly.
 106          */
 107         if (lowmem_deathpending &&
 108             time_before_eq(jiffies, lowmem_deathpending_timeout))
 109                 return 0;
 110
 111         if (lowmem_adj_size < array_size)
 112                 array_size = lowmem_adj_size;
 113         if (lowmem_minfree_size < array_size)
 114                 array_size = lowmem_minfree_size;
 115         for (i = 0; i < array_size; i++) {
 116                 if (other_free < lowmem_minfree[i] &&
 117                     other_file < lowmem_minfree[i]) {
 118                         min_adj = lowmem_adj[i];
 119                         break;
 120                 }
 121         }
 122         if (sc->nr_to_scan > 0)
 123                 lowmem_print(3, "lowmem_shrink %lu, %x, ofree %d %d, ma %d\n",
 124                                 sc->nr_to_scan, sc->gfp_mask, other_free,
 125                                 other_file, min_adj);
 126         rem = global_page_state(NR_ACTIVE_ANON) +
 127                 global_page_state(NR_ACTIVE_FILE) +
 128                 global_page_state(NR_INACTIVE_ANON) +
 129                 global_page_state(NR_INACTIVE_FILE);
 130         if (sc->nr_to_scan <= 0 || min_adj == OOM_ADJUST_MAX + 1) {
 131                 lowmem_print(5, "lowmem_shrink %lu, %x, return %d\n",
 132                              sc->nr_to_scan, sc->gfp_mask, rem);
 133                 return rem;
 134         }
 135         selected_oom_adj = min_adj;
 136
 137         read_lock(&tasklist_lock);
 138         for_each_process(p) {
 139                 struct mm_struct *mm;
 140                 struct signal_struct *sig;
 141                 int oom_adj;
 142
 143                 task_lock(p);
 144                 mm = p->mm;
 145                 sig = p->signal;
 146                 if (!mm || !sig) {
 147                         task_unlock(p);
 148                         continue;
 149                 }
 150                 oom_adj = sig->oom_adj;
 151                 if (oom_adj < min_adj) {
 152                         task_unlock(p);
 153                         continue;
 154                 }
 155                 tasksize = get_mm_rss(mm);
 156                 task_unlock(p);
 157                 if (tasksize <= 0)
 158                         continue;
 159                 if (selected) {
 160                         if (oom_adj < selected_oom_adj)
 161                                 continue;
 162                         if (oom_adj == selected_oom_adj &&
 163                             tasksize <= selected_tasksize)
 164                                 continue;
 165                 }
 166                 selected = p;
 167                 selected_tasksize = tasksize;
 168                 selected_oom_adj = oom_adj;
 169                 lowmem_print(2, "select %d (%s), adj %d, size %d, to kill\n",
 170                              p->pid, p->comm, oom_adj, tasksize);
 171         }
 172         if (selected) {
 173                 lowmem_print(1, "send sigkill to %d (%s), adj %d, size %d\n",
 174                              selected->pid, selected->comm,
 175                              selected_oom_adj, selected_tasksize);
 176                 /*
 177                  * If CONFIG_PROFILING is off, then task_handoff_register()
 178                  * is a nop. In that case we don't want to stall the killer
 179                  * by setting lowmem_deathpending.
 180                  */
 181 #ifdef CONFIG_PROFILING
 182                 lowmem_deathpending = selected;
 183                 lowmem_deathpending_timeout = jiffies + HZ;
 184                 task_handoff_register(&task_nb);
 185 #endif
 186                 force_sig(SIGKILL, selected);
 187                 rem -= selected_tasksize;
 188         }
 189         lowmem_print(4, "lowmem_shrink %lu, %x, return %d\n",
 190                      sc->nr_to_scan, sc->gfp_mask, rem);
 191         read_unlock(&tasklist_lock);
 192         return rem;
 193 }
 194
 195 static struct shrinker lowmem_shrinker = {
 196         .shrink = lowmem_shrink,
 197         .seeks = DEFAULT_SEEKS * 16
 198 };
 199
 200 static int __init lowmem_init(void)
 201 {
 202         register_shrinker(&lowmem_shrinker);
 203         return 0;
 204 }
 205
 206 static void __exit lowmem_exit(void)
 207 {
 208         unregister_shrinker(&lowmem_shrinker);
 209 }
 210
 211 module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR);
 212 module_param_array_named(adj, lowmem_adj, int, &lowmem_adj_size,
 213                          S_IRUGO | S_IWUSR);
 214 module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
 215                          S_IRUGO | S_IWUSR);
 216 module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR);
 217
 218 module_init(lowmem_init);
 219 module_exit(lowmem_exit);
 220
 221 MODULE_LICENSE("GPL");
 222