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 #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/profile.h>
  43 #include <linux/notifier.h>
  44
  45 static uint32_t lowmem_debug_level = 1;
  46 static short lowmem_adj[6] = {
  47         0,
  48         1,
  49         6,
  50         12,
  51 };
  52 static int lowmem_adj_size = 4;
  53 static int lowmem_minfree[6] = {
  54         3 * 512,        /* 6MB */
  55         2 * 1024,       /* 8MB */
  56         4 * 1024,       /* 16MB */
  57         16 * 1024,      /* 64MB */
  58 };
  59 static int lowmem_minfree_size = 4;
  60
  61 static unsigned long lowmem_deathpending_timeout;
  62
  63 #define lowmem_print(level, x...)                       \
  64         do {                                            \
  65                 if (lowmem_debug_level >= (level))      \
  66                         pr_info(x);                     \
  67         } while (0)
  68
  69 static unsigned long lowmem_count(struct shrinker *s,
  70                                   struct shrink_control *sc)
  71 {
  72         return global_page_state(NR_ACTIVE_ANON) +
  73                 global_page_state(NR_ACTIVE_FILE) +
  74                 global_page_state(NR_INACTIVE_ANON) +
  75                 global_page_state(NR_INACTIVE_FILE);
  76 }
  77
  78 static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc)
  79 {
  80         struct task_struct *tsk;
  81         struct task_struct *selected = NULL;
  82         unsigned long rem = 0;
  83         int tasksize;
  84         int i;
  85         short min_score_adj = OOM_SCORE_ADJ_MAX + 1;
  86         int selected_tasksize = 0;
  87         short selected_oom_score_adj;
  88         int array_size = ARRAY_SIZE(lowmem_adj);
  89         int other_free = global_page_state(NR_FREE_PAGES) - totalreserve_pages;
  90         int other_file = global_page_state(NR_FILE_PAGES) -
  91                                                 global_page_state(NR_SHMEM) -
  92                                                 total_swapcache_pages();
  93
  94         if (lowmem_adj_size < array_size)
  95                 array_size = lowmem_adj_size;
  96         if (lowmem_minfree_size < array_size)
  97                 array_size = lowmem_minfree_size;
  98         for (i = 0; i < array_size; i++) {
  99                 if (other_free < lowmem_minfree[i] &&
 100                     other_file < lowmem_minfree[i]) {
 101                         min_score_adj = lowmem_adj[i];
 102                         break;
 103                 }
 104         }
 105
 106         lowmem_print(3, "lowmem_scan %lu, %x, ofree %d %d, ma %hd\n",
 107                         sc->nr_to_scan, sc->gfp_mask, other_free,
 108                         other_file, min_score_adj);
 109
 110         if (min_score_adj == OOM_SCORE_ADJ_MAX + 1) {
 111                 lowmem_print(5, "lowmem_scan %lu, %x, return 0\n",
 112                              sc->nr_to_scan, sc->gfp_mask);
 113                 return 0;
 114         }
 115
 116         selected_oom_score_adj = min_score_adj;
 117
 118         rcu_read_lock();
 119         for_each_process(tsk) {
 120                 struct task_struct *p;
 121                 short oom_score_adj;
 122
 123                 if (tsk->flags & PF_KTHREAD)
 124                         continue;
 125
 126                 p = find_lock_task_mm(tsk);
 127                 if (!p)
 128                         continue;
 129
 130                 if (test_tsk_thread_flag(p, TIF_MEMDIE) &&
 131                     time_before_eq(jiffies, lowmem_deathpending_timeout)) {
 132                         task_unlock(p);
 133                         rcu_read_unlock();
 134                         return 0;
 135                 }
 136                 oom_score_adj = p->signal->oom_score_adj;
 137                 if (oom_score_adj < min_score_adj) {
 138                         task_unlock(p);
 139                         continue;
 140                 }
 141                 tasksize = get_mm_rss(p->mm);
 142                 task_unlock(p);
 143                 if (tasksize <= 0)
 144                         continue;
 145                 if (selected) {
 146                         if (oom_score_adj < selected_oom_score_adj)
 147                                 continue;
 148                         if (oom_score_adj == selected_oom_score_adj &&
 149                             tasksize <= selected_tasksize)
 150                                 continue;
 151                 }
 152                 selected = p;
 153                 selected_tasksize = tasksize;
 154                 selected_oom_score_adj = oom_score_adj;
 155                 lowmem_print(2, "select %d (%s), adj %hd, size %d, to kill\n",
 156                              p->pid, p->comm, oom_score_adj, tasksize);
 157         }
 158         if (selected) {
 159                 task_lock(selected);
 160                 if (!selected->mm) {
 161                         /* Already exited, cannot do mark_tsk_oom_victim() */
 162                         task_unlock(selected);
 163                         goto out;
 164                 }
 165                 /*
 166                  * FIXME: lowmemorykiller shouldn't abuse global OOM killer
 167                  * infrastructure. There is no real reason why the selected
 168                  * task should have access to the memory reserves.
 169                  */
 170                 mark_oom_victim(selected);
 171                 task_unlock(selected);
 172                 lowmem_print(1, "send sigkill to %d (%s), adj %hd, size %d\n",
 173                              selected->pid, selected->comm,
 174                              selected_oom_score_adj, selected_tasksize);
 175                 lowmem_deathpending_timeout = jiffies + HZ;
 176                 send_sig(SIGKILL, selected, 0);
 177                 rem += selected_tasksize;
 178         }
 179 out:
 180         lowmem_print(4, "lowmem_scan %lu, %x, return %lu\n",
 181                      sc->nr_to_scan, sc->gfp_mask, rem);
 182         rcu_read_unlock();
 183         return rem;
 184 }
 185
 186 static struct shrinker lowmem_shrinker = {
 187         .scan_objects = lowmem_scan,
 188         .count_objects = lowmem_count,
 189         .seeks = DEFAULT_SEEKS * 16
 190 };
 191
 192 static int __init lowmem_init(void)
 193 {
 194         register_shrinker(&lowmem_shrinker);
 195         return 0;
 196 }
 197
 198 static void __exit lowmem_exit(void)
 199 {
 200         unregister_shrinker(&lowmem_shrinker);
 201 }
 202
 203 module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR);
 204 module_param_array_named(adj, lowmem_adj, short, &lowmem_adj_size,
 205                          S_IRUGO | S_IWUSR);
 206 module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
 207                          S_IRUGO | S_IWUSR);
 208 module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR);
 209
 210 module_init(lowmem_init);
 211 module_exit(lowmem_exit);
 212
 213 MODULE_LICENSE("GPL");
 214