drivers/staging/android/lowmemorykiller.c - kernel/quantenna - Git at Google

 /* drivers/misc/lowmemorykiller.c
  *
  * The lowmemorykiller driver lets user-space specify a set of memory thresholds
  * where processes with a range of oom_score_adj values will get killed. Specify
  * the minimum oom_score_adj values in
  * /sys/module/lowmemorykiller/parameters/adj and the number of free pages in
  * /sys/module/lowmemorykiller/parameters/minfree. Both files take a comma
  * separated list of numbers in ascending order.
  *
  * For example, write "0,8" to /sys/module/lowmemorykiller/parameters/adj and
  * "1024,4096" to /sys/module/lowmemorykiller/parameters/minfree to kill
  * processes with a oom_score_adj value of 8 or higher when the free memory
  * drops below 4096 pages and kill processes with a oom_score_adj value of 0 or
  * higher when the free memory drops below 1024 pages.
  *
  * The driver considers memory used for caches to be free, but if a large
  * percentage of the cached memory is locked this can be very inaccurate
  * and processes may not get killed until the normal oom killer is triggered.
  *
  * Copyright (C) 2007-2008 Google, Inc.
  *
  * This software is licensed under the terms of the GNU General Public
  * License version 2, as published by the Free Software Foundation, and
  * may be copied, distributed, and modified under those terms.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/init.h>
 #include <linux/moduleparam.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/oom.h>
 #include <linux/sched.h>
 #include <linux/swap.h>
 #include <linux/rcupdate.h>
 #include <linux/profile.h>
 #include <linux/notifier.h>

 static u32 lowmem_debug_level = 1;
 static short lowmem_adj[6] = {
 	0,
 	1,
 	6,
 	12,
 };

 static int lowmem_adj_size = 4;
 static int lowmem_minfree[6] = {
 	3 * 512,	/* 6MB */
 	2 * 1024,	/* 8MB */
 	4 * 1024,	/* 16MB */
 	16 * 1024,	/* 64MB */
 };

 static int lowmem_minfree_size = 4;

 static unsigned long lowmem_deathpending_timeout;

 #define lowmem_print(level, x...)			\
 	do {						\
 		if (lowmem_debug_level >= (level))	\
 			pr_info(x);			\
 	} while (0)

 static unsigned long lowmem_count(struct shrinker *s,
 				  struct shrink_control *sc)
 {
 	return global_page_state(NR_ACTIVE_ANON) +
 		global_page_state(NR_ACTIVE_FILE) +
 		global_page_state(NR_INACTIVE_ANON) +
 		global_page_state(NR_INACTIVE_FILE);
 }

 static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc)
 {
 	struct task_struct *tsk;
 	struct task_struct *selected = NULL;
 	unsigned long rem = 0;
 	int tasksize;
 	int i;
 	short min_score_adj = OOM_SCORE_ADJ_MAX + 1;
 	int minfree = 0;
 	int selected_tasksize = 0;
 	short selected_oom_score_adj;
 	int array_size = ARRAY_SIZE(lowmem_adj);
 	int other_free = global_page_state(NR_FREE_PAGES) - totalreserve_pages;
 	int other_file = global_page_state(NR_FILE_PAGES) -
 						global_page_state(NR_SHMEM) -
 						total_swapcache_pages();

 	if (lowmem_adj_size < array_size)
 		array_size = lowmem_adj_size;
 	if (lowmem_minfree_size < array_size)
 		array_size = lowmem_minfree_size;
 	for (i = 0; i < array_size; i++) {
 		minfree = lowmem_minfree[i];
 		if (other_free < minfree && other_file < minfree) {
 			min_score_adj = lowmem_adj[i];
 			break;
 		}
 	}

 	lowmem_print(3, "lowmem_scan %lu, %x, ofree %d %d, ma %hd\n",
 		     sc->nr_to_scan, sc->gfp_mask, other_free,
 		     other_file, min_score_adj);

 	if (min_score_adj == OOM_SCORE_ADJ_MAX + 1) {
 		lowmem_print(5, "lowmem_scan %lu, %x, return 0\n",
 			     sc->nr_to_scan, sc->gfp_mask);
 		return 0;
 	}

 	selected_oom_score_adj = min_score_adj;

 	rcu_read_lock();
 	for_each_process(tsk) {
 		struct task_struct *p;
 		short oom_score_adj;

 		if (tsk->flags & PF_KTHREAD)
 			continue;

 		p = find_lock_task_mm(tsk);
 		if (!p)
 			continue;

 		if (task_lmk_waiting(p) &&
 		    time_before_eq(jiffies, lowmem_deathpending_timeout)) {
 			task_unlock(p);
 			rcu_read_unlock();
 			return 0;
 		}
 		oom_score_adj = p->signal->oom_score_adj;
 		if (oom_score_adj < min_score_adj) {
 			task_unlock(p);
 			continue;
 		}
 		tasksize = get_mm_rss(p->mm);
 		task_unlock(p);
 		if (tasksize <= 0)
 			continue;
 		if (selected) {
 			if (oom_score_adj < selected_oom_score_adj)
 				continue;
 			if (oom_score_adj == selected_oom_score_adj &&
 			    tasksize <= selected_tasksize)
 				continue;
 		}
 		selected = p;
 		selected_tasksize = tasksize;
 		selected_oom_score_adj = oom_score_adj;
 		lowmem_print(2, "select '%s' (%d), adj %hd, size %d, to kill\n",
 			     p->comm, p->pid, oom_score_adj, tasksize);
 	}
 	if (selected) {
 		task_lock(selected);
 		send_sig(SIGKILL, selected, 0);
 		if (selected->mm)
 			task_set_lmk_waiting(selected);
 		task_unlock(selected);
 		lowmem_print(1, "Killing '%s' (%d), adj %hd,\n"
 				 "   to free %ldkB on behalf of '%s' (%d) because\n"
 				 "   cache %ldkB is below limit %ldkB for oom_score_adj %hd\n"
 				 "   Free memory is %ldkB above reserved\n",
 			     selected->comm, selected->pid,
 			     selected_oom_score_adj,
 			     selected_tasksize * (long)(PAGE_SIZE / 1024),
 			     current->comm, current->pid,
 			     other_file * (long)(PAGE_SIZE / 1024),
 			     minfree * (long)(PAGE_SIZE / 1024),
 			     min_score_adj,
 			     other_free * (long)(PAGE_SIZE / 1024));
 		lowmem_deathpending_timeout = jiffies + HZ;
 		rem += selected_tasksize;
 	}

 	lowmem_print(4, "lowmem_scan %lu, %x, return %lu\n",
 		     sc->nr_to_scan, sc->gfp_mask, rem);
 	rcu_read_unlock();
 	return rem;
 }

 static struct shrinker lowmem_shrinker = {
 	.scan_objects = lowmem_scan,
 	.count_objects = lowmem_count,
 	.seeks = DEFAULT_SEEKS * 16
 };

 static int __init lowmem_init(void)
 {
 	register_shrinker(&lowmem_shrinker);
 	return 0;
 }
 device_initcall(lowmem_init);

 /*
  * not really modular, but the easiest way to keep compat with existing
  * bootargs behaviour is to continue using module_param here.
  */
 module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR);
 module_param_array_named(adj, lowmem_adj, short, &lowmem_adj_size,
 			 S_IRUGO | S_IWUSR);
 module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
 			 S_IRUGO | S_IWUSR);
 module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR);
	/* drivers/misc/lowmemorykiller.c
	*
	* The lowmemorykiller driver lets user-space specify a set of memory thresholds
	* where processes with a range of oom_score_adj values will get killed. Specify
	* the minimum oom_score_adj values in
	* /sys/module/lowmemorykiller/parameters/adj and the number of free pages in
	* /sys/module/lowmemorykiller/parameters/minfree. Both files take a comma
	* separated list of numbers in ascending order.
	*
	* For example, write "0,8" to /sys/module/lowmemorykiller/parameters/adj and
	* "1024,4096" to /sys/module/lowmemorykiller/parameters/minfree to kill
	* processes with a oom_score_adj value of 8 or higher when the free memory
	* drops below 4096 pages and kill processes with a oom_score_adj value of 0 or
	* higher when the free memory drops below 1024 pages.
	*
	* The driver considers memory used for caches to be free, but if a large
	* percentage of the cached memory is locked this can be very inaccurate
	* and processes may not get killed until the normal oom killer is triggered.
	*
	* Copyright (C) 2007-2008 Google, Inc.
	*
	* This software is licensed under the terms of the GNU General Public
	* License version 2, as published by the Free Software Foundation, and
	* may be copied, distributed, and modified under those terms.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/init.h>
	#include <linux/moduleparam.h>
	#include <linux/kernel.h>
	#include <linux/mm.h>
	#include <linux/oom.h>
	#include <linux/sched.h>
	#include <linux/swap.h>
	#include <linux/rcupdate.h>
	#include <linux/profile.h>
	#include <linux/notifier.h>

	static u32 lowmem_debug_level = 1;
	static short lowmem_adj[6] = {
	0,
	1,
	6,
	12,
	};

	static int lowmem_adj_size = 4;
	static int lowmem_minfree[6] = {
	3 * 512, /* 6MB */
	2 * 1024, /* 8MB */
	4 * 1024, /* 16MB */
	16 * 1024, /* 64MB */
	};

	static int lowmem_minfree_size = 4;

	static unsigned long lowmem_deathpending_timeout;

	#define lowmem_print(level, x...) \
	do { \
	if (lowmem_debug_level >= (level)) \
	pr_info(x); \
	} while (0)

	static unsigned long lowmem_count(struct shrinker *s,
	struct shrink_control *sc)
	{
	return global_page_state(NR_ACTIVE_ANON) +
	global_page_state(NR_ACTIVE_FILE) +
	global_page_state(NR_INACTIVE_ANON) +
	global_page_state(NR_INACTIVE_FILE);
	}

	static unsigned long lowmem_scan(struct shrinker s, struct shrink_control sc)
	{
	struct task_struct *tsk;
	struct task_struct *selected = NULL;
	unsigned long rem = 0;
	int tasksize;
	int i;
	short min_score_adj = OOM_SCORE_ADJ_MAX + 1;
	int minfree = 0;
	int selected_tasksize = 0;
	short selected_oom_score_adj;
	int array_size = ARRAY_SIZE(lowmem_adj);
	int other_free = global_page_state(NR_FREE_PAGES) - totalreserve_pages;
	int other_file = global_page_state(NR_FILE_PAGES) -
	global_page_state(NR_SHMEM) -
	total_swapcache_pages();

	if (lowmem_adj_size < array_size)
	array_size = lowmem_adj_size;
	if (lowmem_minfree_size < array_size)
	array_size = lowmem_minfree_size;
	for (i = 0; i < array_size; i++) {
	minfree = lowmem_minfree[i];
	if (other_free < minfree && other_file < minfree) {
	min_score_adj = lowmem_adj[i];
	break;
	}
	}

	lowmem_print(3, "lowmem_scan %lu, %x, ofree %d %d, ma %hd\n",
	sc->nr_to_scan, sc->gfp_mask, other_free,
	other_file, min_score_adj);

	if (min_score_adj == OOM_SCORE_ADJ_MAX + 1) {
	lowmem_print(5, "lowmem_scan %lu, %x, return 0\n",
	sc->nr_to_scan, sc->gfp_mask);
	return 0;
	}

	selected_oom_score_adj = min_score_adj;

	rcu_read_lock();
	for_each_process(tsk) {
	struct task_struct *p;
	short oom_score_adj;

	if (tsk->flags & PF_KTHREAD)
	continue;

	p = find_lock_task_mm(tsk);
	if (!p)
	continue;

	if (task_lmk_waiting(p) &&
	time_before_eq(jiffies, lowmem_deathpending_timeout)) {
	task_unlock(p);
	rcu_read_unlock();
	return 0;
	}
	oom_score_adj = p->signal->oom_score_adj;
	if (oom_score_adj < min_score_adj) {
	task_unlock(p);
	continue;
	}
	tasksize = get_mm_rss(p->mm);
	task_unlock(p);
	if (tasksize <= 0)
	continue;
	if (selected) {
	if (oom_score_adj < selected_oom_score_adj)
	continue;
	if (oom_score_adj == selected_oom_score_adj &&
	tasksize <= selected_tasksize)
	continue;
	}
	selected = p;
	selected_tasksize = tasksize;
	selected_oom_score_adj = oom_score_adj;
	lowmem_print(2, "select '%s' (%d), adj %hd, size %d, to kill\n",
	p->comm, p->pid, oom_score_adj, tasksize);
	}
	if (selected) {
	task_lock(selected);
	send_sig(SIGKILL, selected, 0);
	if (selected->mm)
	task_set_lmk_waiting(selected);
	task_unlock(selected);
	lowmem_print(1, "Killing '%s' (%d), adj %hd,\n"
	" to free %ldkB on behalf of '%s' (%d) because\n"
	" cache %ldkB is below limit %ldkB for oom_score_adj %hd\n"
	" Free memory is %ldkB above reserved\n",
	selected->comm, selected->pid,
	selected_oom_score_adj,
	selected_tasksize * (long)(PAGE_SIZE / 1024),
	current->comm, current->pid,
	other_file * (long)(PAGE_SIZE / 1024),
	minfree * (long)(PAGE_SIZE / 1024),
	min_score_adj,
	other_free * (long)(PAGE_SIZE / 1024));
	lowmem_deathpending_timeout = jiffies + HZ;
	rem += selected_tasksize;
	}

	lowmem_print(4, "lowmem_scan %lu, %x, return %lu\n",
	sc->nr_to_scan, sc->gfp_mask, rem);
	rcu_read_unlock();
	return rem;
	}

	static struct shrinker lowmem_shrinker = {
	.scan_objects = lowmem_scan,
	.count_objects = lowmem_count,
	.seeks = DEFAULT_SEEKS * 16
	};

	static int __init lowmem_init(void)
	{
	register_shrinker(&lowmem_shrinker);
	return 0;
	}
	device_initcall(lowmem_init);

	/*
	* not really modular, but the easiest way to keep compat with existing
	* bootargs behaviour is to continue using module_param here.
	*/
	module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO \| S_IWUSR);
	module_param_array_named(adj, lowmem_adj, short, &lowmem_adj_size,
	S_IRUGO \| S_IWUSR);
	module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
	S_IRUGO \| S_IWUSR);
	module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO \| S_IWUSR);