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 int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
  70 {
  71         struct task_struct *tsk;
  72         struct task_struct *selected = NULL;
  73         int rem = 0;
  74         int tasksize;
  75         int i;
  76         short min_score_adj = OOM_SCORE_ADJ_MAX + 1;
  77         int selected_tasksize = 0;
  78         short selected_oom_score_adj;
  79         int array_size = ARRAY_SIZE(lowmem_adj);
  80         int other_free = global_page_state(NR_FREE_PAGES) - totalreserve_pages;
  81         int other_file = global_page_state(NR_FILE_PAGES) -
  82                                                 global_page_state(NR_SHMEM);
  83
  84         if (lowmem_adj_size < array_size)
  85                 array_size = lowmem_adj_size;
  86         if (lowmem_minfree_size < array_size)
  87                 array_size = lowmem_minfree_size;
  88         for (i = 0; i < array_size; i++) {
  89                 if (other_free < lowmem_minfree[i] &&
  90                     other_file < lowmem_minfree[i]) {
  91                         min_score_adj = lowmem_adj[i];
  92                         break;
  93                 }
  94         }
  95         if (sc->nr_to_scan > 0)
  96                 lowmem_print(3, "lowmem_shrink %lu, %x, ofree %d %d, ma %hd\n",
  97                                 sc->nr_to_scan, sc->gfp_mask, other_free,
  98                                 other_file, min_score_adj);
  99         rem = global_page_state(NR_ACTIVE_ANON) +
 100                 global_page_state(NR_ACTIVE_FILE) +
 101                 global_page_state(NR_INACTIVE_ANON) +
 102                 global_page_state(NR_INACTIVE_FILE);
 103         if (sc->nr_to_scan <= 0 || min_score_adj == OOM_SCORE_ADJ_MAX + 1) {
 104                 lowmem_print(5, "lowmem_shrink %lu, %x, return %d\n",
 105                              sc->nr_to_scan, sc->gfp_mask, rem);
 106                 return rem;
 107         }
 108         selected_oom_score_adj = min_score_adj;
 109
 110         rcu_read_lock();
 111         for_each_process(tsk) {
 112                 struct task_struct *p;
 113                 short oom_score_adj;
 114
 115                 if (tsk->flags & PF_KTHREAD)
 116                         continue;
 117
 118                 p = find_lock_task_mm(tsk);
 119                 if (!p)
 120                         continue;
 121
 122                 if (test_tsk_thread_flag(p, TIF_MEMDIE) &&
 123                     time_before_eq(jiffies, lowmem_deathpending_timeout)) {
 124                         task_unlock(p);
 125                         rcu_read_unlock();
 126                         return 0;
 127                 }
 128                 oom_score_adj = p->signal->oom_score_adj;
 129                 if (oom_score_adj < min_score_adj) {
 130                         task_unlock(p);
 131                         continue;
 132                 }
 133                 tasksize = get_mm_rss(p->mm);
 134                 task_unlock(p);
 135                 if (tasksize <= 0)
 136                         continue;
 137                 if (selected) {
 138                         if (oom_score_adj < selected_oom_score_adj)
 139                                 continue;
 140                         if (oom_score_adj == selected_oom_score_adj &&
 141                             tasksize <= selected_tasksize)
 142                                 continue;
 143                 }
 144                 selected = p;
 145                 selected_tasksize = tasksize;
 146                 selected_oom_score_adj = oom_score_adj;
 147                 lowmem_print(2, "select %d (%s), adj %hd, size %d, to kill\n",
 148                              p->pid, p->comm, oom_score_adj, tasksize);
 149         }
 150         if (selected) {
 151                 lowmem_print(1, "send sigkill to %d (%s), adj %hd, size %d\n",
 152                              selected->pid, selected->comm,
 153                              selected_oom_score_adj, selected_tasksize);
 154                 lowmem_deathpending_timeout = jiffies + HZ;
 155                 send_sig(SIGKILL, selected, 0);
 156                 set_tsk_thread_flag(selected, TIF_MEMDIE);
 157                 rem -= selected_tasksize;
 158         }
 159         lowmem_print(4, "lowmem_shrink %lu, %x, return %d\n",
 160                      sc->nr_to_scan, sc->gfp_mask, rem);
 161         rcu_read_unlock();
 162         return rem;
 163 }
 164
 165 static struct shrinker lowmem_shrinker = {
 166         .shrink = lowmem_shrink,
 167         .seeks = DEFAULT_SEEKS * 16
 168 };
 169
 170 static int __init lowmem_init(void)
 171 {
 172         register_shrinker(&lowmem_shrinker);
 173         return 0;
 174 }
 175
 176 static void __exit lowmem_exit(void)
 177 {
 178         unregister_shrinker(&lowmem_shrinker);
 179 }
 180
 181 module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR);
 182 module_param_array_named(adj, lowmem_adj, short, &lowmem_adj_size,
 183                          S_IRUGO | S_IWUSR);
 184 module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
 185                          S_IRUGO | S_IWUSR);
 186 module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR);
 187
 188 module_init(lowmem_init);
 189 module_exit(lowmem_exit);
 190
 191 MODULE_LICENSE("GPL");
 192