f61333b96025f142672367750219e428ebbae32d
1 /* drivers/misc/lowmemorykiller.c
3 * Copyright (C) 2007-2008 Google, Inc.
5 * This software is licensed under the terms of the GNU General Public
6 * License version 2, as published by the Free Software Foundation, and
7 * may be copied, distributed, and modified under those terms.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
16 #include <linux/module.h>
17 #include <linux/kernel.h>
19 #include <linux/oom.h>
20 #include <linux/sched.h>
22 static int lowmem_shrink(int nr_to_scan
, gfp_t gfp_mask
);
24 static struct shrinker lowmem_shrinker
= {
25 .shrink
= lowmem_shrink
,
26 .seeks
= DEFAULT_SEEKS
* 16
28 static uint32_t lowmem_debug_level
= 2;
29 static int lowmem_adj
[6] = {
35 static int lowmem_adj_size
= 4;
36 static size_t lowmem_minfree
[6] = {
42 static int lowmem_minfree_size
= 4;
44 #define lowmem_print(level, x...) do { if(lowmem_debug_level >= (level)) printk(x); } while(0)
46 module_param_named(cost
, lowmem_shrinker
.seeks
, int, S_IRUGO
| S_IWUSR
);
47 module_param_array_named(adj
, lowmem_adj
, int, &lowmem_adj_size
, S_IRUGO
| S_IWUSR
);
48 module_param_array_named(minfree
, lowmem_minfree
, uint
, &lowmem_minfree_size
, S_IRUGO
| S_IWUSR
);
49 module_param_named(debug_level
, lowmem_debug_level
, uint
, S_IRUGO
| S_IWUSR
);
51 static int lowmem_shrink(int nr_to_scan
, gfp_t gfp_mask
)
53 struct task_struct
*p
;
54 struct task_struct
*selected
= NULL
;
58 int min_adj
= OOM_ADJUST_MAX
+ 1;
59 int selected_tasksize
= 0;
61 int array_size
= ARRAY_SIZE(lowmem_adj
);
62 int other_free
= global_page_state(NR_FREE_PAGES
);
63 int other_file
= global_page_state(NR_FILE_PAGES
);
65 if (lowmem_adj_size
< array_size
)
66 array_size
= lowmem_adj_size
;
67 if (lowmem_minfree_size
< array_size
)
68 array_size
= lowmem_minfree_size
;
69 for (i
= 0; i
< array_size
; i
++) {
70 if (other_free
< lowmem_minfree
[i
] &&
71 other_file
< lowmem_minfree
[i
]) {
72 min_adj
= lowmem_adj
[i
];
77 lowmem_print(3, "lowmem_shrink %d, %x, ofree %d %d, ma %d\n",
78 nr_to_scan
, gfp_mask
, other_free
, other_file
,
80 rem
= global_page_state(NR_ACTIVE_ANON
) +
81 global_page_state(NR_ACTIVE_FILE
) +
82 global_page_state(NR_INACTIVE_ANON
) +
83 global_page_state(NR_INACTIVE_FILE
);
84 if (nr_to_scan
<= 0 || min_adj
== OOM_ADJUST_MAX
+ 1) {
85 lowmem_print(5, "lowmem_shrink %d, %x, return %d\n",
86 nr_to_scan
, gfp_mask
, rem
);
89 selected_oom_adj
= min_adj
;
91 read_lock(&tasklist_lock
);
97 oom_adj
= p
->oomkilladj
;
98 if (oom_adj
< min_adj
)
100 tasksize
= get_mm_rss(p
->mm
);
104 if (oom_adj
< selected_oom_adj
)
106 if (oom_adj
== selected_oom_adj
&&
107 tasksize
<= selected_tasksize
)
111 selected_tasksize
= tasksize
;
112 selected_oom_adj
= oom_adj
;
113 lowmem_print(2, "select %d (%s), adj %d, size %d, to kill\n",
114 p
->pid
, p
->comm
, oom_adj
, tasksize
);
117 lowmem_print(1, "send sigkill to %d (%s), adj %d, size %d\n",
118 selected
->pid
, selected
->comm
,
119 selected_oom_adj
, selected_tasksize
);
120 force_sig(SIGKILL
, selected
);
121 rem
-= selected_tasksize
;
123 lowmem_print(4, "lowmem_shrink %d, %x, return %d\n",
124 nr_to_scan
, gfp_mask
, rem
);
125 read_unlock(&tasklist_lock
);
129 static int __init
lowmem_init(void)
131 register_shrinker(&lowmem_shrinker
);
135 static void __exit
lowmem_exit(void)
137 unregister_shrinker(&lowmem_shrinker
);
140 module_init(lowmem_init
);
141 module_exit(lowmem_exit
);
143 MODULE_LICENSE("GPL");
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