LXR linux/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
  46static u32 lowmem_debug_level = 1;
  47static short lowmem_adj[6] = {
  48        0,
  49        1,
  50        6,
  51        12,
  52};
  53
  54static int lowmem_adj_size = 4;
  55static int lowmem_minfree[6] = {
  56        3 * 512,        /* 6MB */
  57        2 * 1024,       /* 8MB */
  58        4 * 1024,       /* 16MB */
  59        16 * 1024,      /* 64MB */
  60};
  61
  62static int lowmem_minfree_size = 4;
  63
  64static 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
  72static 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
  81static 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 (test_tsk_thread_flag(p, TIF_MEMDIE) &&
 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                /*
 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                if (selected->mm)
 171                        mark_oom_victim(selected);
 172                task_unlock(selected);
 173                lowmem_print(1, "Killing '%s' (%d), adj %hd,\n"
 174                                 "   to free %ldkB on behalf of '%s' (%d) because\n"
 175                                 "   cache %ldkB is below limit %ldkB for oom_score_adj %hd\n"
 176                                 "   Free memory is %ldkB above reserved\n",
 177                             selected->comm, selected->pid,
 178                             selected_oom_score_adj,
 179                             selected_tasksize * (long)(PAGE_SIZE / 1024),
 180                             current->comm, current->pid,
 181                             other_file * (long)(PAGE_SIZE / 1024),
 182                             minfree * (long)(PAGE_SIZE / 1024),
 183                             min_score_adj,
 184                             other_free * (long)(PAGE_SIZE / 1024));
 185                lowmem_deathpending_timeout = jiffies + HZ;
 186                rem += selected_tasksize;
 187        }
 188
 189        lowmem_print(4, "lowmem_scan %lu, %x, return %lu\n",
 190                     sc->nr_to_scan, sc->gfp_mask, rem);
 191        rcu_read_unlock();
 192        return rem;
 193}
 194
 195static struct shrinker lowmem_shrinker = {
 196        .scan_objects = lowmem_scan,
 197        .count_objects = lowmem_count,
 198        .seeks = DEFAULT_SEEKS * 16
 199};
 200
 201static int __init lowmem_init(void)
 202{
 203        register_shrinker(&lowmem_shrinker);
 204        return 0;
 205}
 206device_initcall(lowmem_init);
 207
 208/*
 209 * not really modular, but the easiest way to keep compat with existing
 210 * bootargs behaviour is to continue using module_param here.
 211 */
 212module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR);
 213module_param_array_named(adj, lowmem_adj, short, &lowmem_adj_size,
 214                         S_IRUGO | S_IWUSR);
 215module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
 216                         S_IRUGO | S_IWUSR);
 217module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR);
 218
 219