1 /* drivers/misc/lowmemorykiller.c
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.
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.
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.
20 * Copyright (C) 2007-2008 Google, Inc.
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.
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.
33 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
35 #include <linux/module.h>
36 #include <linux/kernel.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>
45 static uint32_t lowmem_debug_level
= 1;
46 static short lowmem_adj
[6] = {
52 static int lowmem_adj_size
= 4;
53 static int lowmem_minfree
[6] = {
59 static int lowmem_minfree_size
= 4;
61 static unsigned long lowmem_deathpending_timeout
;
63 #define lowmem_print(level, x...) \
65 if (lowmem_debug_level >= (level)) \
69 static unsigned long lowmem_count(struct shrinker
*s
,
70 struct shrink_control
*sc
)
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
);
78 static unsigned long lowmem_scan(struct shrinker
*s
, struct shrink_control
*sc
)
80 struct task_struct
*tsk
;
81 struct task_struct
*selected
= NULL
;
82 unsigned long rem
= 0;
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
);
93 if (lowmem_adj_size
< array_size
)
94 array_size
= lowmem_adj_size
;
95 if (lowmem_minfree_size
< array_size
)
96 array_size
= lowmem_minfree_size
;
97 for (i
= 0; i
< array_size
; i
++) {
98 if (other_free
< lowmem_minfree
[i
] &&
99 other_file
< lowmem_minfree
[i
]) {
100 min_score_adj
= lowmem_adj
[i
];
105 lowmem_print(3, "lowmem_scan %lu, %x, ofree %d %d, ma %hd\n",
106 sc
->nr_to_scan
, sc
->gfp_mask
, other_free
,
107 other_file
, min_score_adj
);
109 if (min_score_adj
== OOM_SCORE_ADJ_MAX
+ 1) {
110 lowmem_print(5, "lowmem_scan %lu, %x, return 0\n",
111 sc
->nr_to_scan
, sc
->gfp_mask
);
115 selected_oom_score_adj
= min_score_adj
;
118 for_each_process(tsk
) {
119 struct task_struct
*p
;
122 if (tsk
->flags
& PF_KTHREAD
)
125 p
= find_lock_task_mm(tsk
);
129 if (test_tsk_thread_flag(p
, TIF_MEMDIE
) &&
130 time_before_eq(jiffies
, lowmem_deathpending_timeout
)) {
135 oom_score_adj
= p
->signal
->oom_score_adj
;
136 if (oom_score_adj
< min_score_adj
) {
140 tasksize
= get_mm_rss(p
->mm
);
145 if (oom_score_adj
< selected_oom_score_adj
)
147 if (oom_score_adj
== selected_oom_score_adj
&&
148 tasksize
<= selected_tasksize
)
152 selected_tasksize
= tasksize
;
153 selected_oom_score_adj
= oom_score_adj
;
154 lowmem_print(2, "select %d (%s), adj %hd, size %d, to kill\n",
155 p
->pid
, p
->comm
, oom_score_adj
, tasksize
);
158 lowmem_print(1, "send sigkill to %d (%s), adj %hd, size %d\n",
159 selected
->pid
, selected
->comm
,
160 selected_oom_score_adj
, selected_tasksize
);
161 lowmem_deathpending_timeout
= jiffies
+ HZ
;
162 send_sig(SIGKILL
, selected
, 0);
163 set_tsk_thread_flag(selected
, TIF_MEMDIE
);
164 rem
+= selected_tasksize
;
167 lowmem_print(4, "lowmem_scan %lu, %x, return %lu\n",
168 sc
->nr_to_scan
, sc
->gfp_mask
, rem
);
173 static struct shrinker lowmem_shrinker
= {
174 .scan_objects
= lowmem_scan
,
175 .count_objects
= lowmem_count
,
176 .seeks
= DEFAULT_SEEKS
* 16
179 static int __init
lowmem_init(void)
181 register_shrinker(&lowmem_shrinker
);
185 static void __exit
lowmem_exit(void)
187 unregister_shrinker(&lowmem_shrinker
);
190 module_param_named(cost
, lowmem_shrinker
.seeks
, int, S_IRUGO
| S_IWUSR
);
191 module_param_array_named(adj
, lowmem_adj
, short, &lowmem_adj_size
,
193 module_param_array_named(minfree
, lowmem_minfree
, uint
, &lowmem_minfree_size
,
195 module_param_named(debug_level
, lowmem_debug_level
, uint
, S_IRUGO
| S_IWUSR
);
197 module_init(lowmem_init
);
198 module_exit(lowmem_exit
);
200 MODULE_LICENSE("GPL");