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