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 u32 lowmem_debug_level = 1;
  47 static short lowmem_adj[6] = {
  48         0,
  49         1,
  50         6,
  51         12,
  52 };
  53
  54 static int lowmem_adj_size = 4;
  55 static int lowmem_minfree[6] = {
  56         3 * 512,        /* 6MB */
  57         2 * 1024,       /* 8MB */
  58         4 * 1024,       /* 16MB */
  59         16 * 1024,      /* 64MB */
  60 };
  61
  62 static int lowmem_minfree_size = 4;
  63
  64 static unsigned long lowmem_deathpending_timeout;
  65
  66 #define lowmem_print(level, x...)                       \
  67         do {                                            \
  68                 if (lowmem_debug_level >= (level))      \
  69                         pr_info(x);                     \
  70         } while (0)
  71
  72 static unsigned long lowmem_count(struct shrinker *s,
  73                                   struct shrink_control *sc)
  74 {
  75         return global_page_state(NR_ACTIVE_ANON) +
  76                 global_page_state(NR_ACTIVE_FILE) +
  77                 global_page_state(NR_INACTIVE_ANON) +
  78                 global_page_state(NR_INACTIVE_FILE);
  79 }
  80
  81 static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc)
  82 {
  83         struct task_struct *tsk;
  84         struct task_struct *selected = NULL;
  85         unsigned long rem = 0;
  86         int tasksize;
  87         int i;
  88         short min_score_adj = OOM_SCORE_ADJ_MAX + 1;
  89         int minfree = 0;
  90         int selected_tasksize = 0;
  91         short selected_oom_score_adj;
  92         int array_size = ARRAY_SIZE(lowmem_adj);
  93         int other_free = global_page_state(NR_FREE_PAGES) - totalreserve_pages;
  94         int other_file = global_page_state(NR_FILE_PAGES) -
  95                                                 global_page_state(NR_SHMEM) -
  96                                                 total_swapcache_pages();
  97
  98         if (lowmem_adj_size < array_size)
  99                 array_size = lowmem_adj_size;
 100         if (lowmem_minfree_size < array_size)
 101                 array_size = lowmem_minfree_size;
 102         for (i = 0; i < array_size; i++) {
 103                 minfree = lowmem_minfree[i];
 104                 if (other_free < minfree && other_file < minfree) {
 105                         min_score_adj = lowmem_adj[i];
 106                         break;
 107                 }
 108         }
 109
 110         lowmem_print(3, "lowmem_scan %lu, %x, ofree %d %d, ma %hd\n",
 111                      sc->nr_to_scan, sc->gfp_mask, other_free,
 112                      other_file, min_score_adj);
 113
 114         if (min_score_adj == OOM_SCORE_ADJ_MAX + 1) {
 115                 lowmem_print(5, "lowmem_scan %lu, %x, return 0\n",
 116                              sc->nr_to_scan, sc->gfp_mask);
 117                 return 0;
 118         }
 119
 120         selected_oom_score_adj = min_score_adj;
 121
 122         rcu_read_lock();
 123         for_each_process(tsk) {
 124                 struct task_struct *p;
 125                 short oom_score_adj;
 126
 127                 if (tsk->flags & PF_KTHREAD)
 128                         continue;
 129
 130                 p = find_lock_task_mm(tsk);
 131                 if (!p)
 132                         continue;
 133
 134                 if (task_lmk_waiting(p) && p->mm &&
 135                     time_before_eq(jiffies, lowmem_deathpending_timeout)) {
 136                         task_unlock(p);
 137                         rcu_read_unlock();
 138                         return 0;
 139                 }
 140                 oom_score_adj = p->signal->oom_score_adj;
 141                 if (oom_score_adj < min_score_adj) {
 142                         task_unlock(p);
 143                         continue;
 144                 }
 145                 tasksize = get_mm_rss(p->mm);
 146                 task_unlock(p);
 147                 if (tasksize <= 0)
 148                         continue;
 149                 if (selected) {
 150                         if (oom_score_adj < selected_oom_score_adj)
 151                                 continue;
 152                         if (oom_score_adj == selected_oom_score_adj &&
 153                             tasksize <= selected_tasksize)
 154                                 continue;
 155                 }
 156                 selected = p;
 157                 selected_tasksize = tasksize;
 158                 selected_oom_score_adj = oom_score_adj;
 159                 lowmem_print(2, "select '%s' (%d), adj %hd, size %d, to kill\n",
 160                              p->comm, p->pid, oom_score_adj, tasksize);
 161         }
 162         if (selected) {
 163                 task_lock(selected);
 164                 send_sig(SIGKILL, selected, 0);
 165                 if (selected->mm)
 166                         task_set_lmk_waiting(selected);
 167                 task_unlock(selected);
 168                 lowmem_print(1, "Killing '%s' (%d), adj %hd,\n"
 169                                  "   to free %ldkB on behalf of '%s' (%d) because\n"
 170                                  "   cache %ldkB is below limit %ldkB for oom_score_adj %hd\n"
 171                                  "   Free memory is %ldkB above reserved\n",
 172                              selected->comm, selected->pid,
 173                              selected_oom_score_adj,
 174                              selected_tasksize * (long)(PAGE_SIZE / 1024),
 175                              current->comm, current->pid,
 176                              other_file * (long)(PAGE_SIZE / 1024),
 177                              minfree * (long)(PAGE_SIZE / 1024),
 178                              min_score_adj,
 179                              other_free * (long)(PAGE_SIZE / 1024));
 180                 lowmem_deathpending_timeout = jiffies + HZ;
 181                 rem += selected_tasksize;
 182         }
 183
 184         lowmem_print(4, "lowmem_scan %lu, %x, return %lu\n",
 185                      sc->nr_to_scan, sc->gfp_mask, rem);
 186         rcu_read_unlock();
 187         return rem;
 188 }
 189
 190 static struct shrinker lowmem_shrinker = {
 191         .scan_objects = lowmem_scan,
 192         .count_objects = lowmem_count,
 193         .seeks = DEFAULT_SEEKS * 16
 194 };
 195
 196 static int __init lowmem_init(void)
 197 {
 198         register_shrinker(&lowmem_shrinker);
 199         return 0;
 200 }
 201 device_initcall(lowmem_init);
 202
 203 /*
 204  * not really modular, but the easiest way to keep compat with existing
 205  * bootargs behaviour is to continue using module_param here.
 206  */
 207 module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR);
 208 module_param_array_named(adj, lowmem_adj, short, &lowmem_adj_size,
 209                          S_IRUGO | S_IWUSR);
 210 module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
 211                          S_IRUGO | S_IWUSR);
 212 module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR);
 213