drivers/staging/android/lowmemorykiller.c - manifest_repos/kernel - 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>
 #include <linux/circ_buf.h>
 #include <linux/proc_fs.h>
 #include <linux/slab.h>
 #include <linux/poll.h>

 #ifdef CONFIG_AMLOGIC_CMA
 #include <linux/amlogic/aml_cma.h>
 #endif

 #define CREATE_TRACE_POINTS
 #include "trace/lowmemorykiller.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 DECLARE_WAIT_QUEUE_HEAD(event_wait);
 static DEFINE_SPINLOCK(lmk_event_lock);
 static struct circ_buf event_buffer;
 #define MAX_BUFFERED_EVENTS 8
 #define MAX_TASKNAME 128

 struct lmk_event {
 	char taskname[MAX_TASKNAME];
 	pid_t pid;
 	uid_t uid;
 	pid_t group_leader_pid;
 	unsigned long min_flt;
 	unsigned long maj_flt;
 	unsigned long rss_in_pages;
 	short oom_score_adj;
 	short min_score_adj;
 	unsigned long long start_time;
 	struct list_head list;
 };

 void handle_lmk_event(struct task_struct *selected, short min_score_adj)
 {
 	int head;
 	int tail;
 	struct lmk_event *events;
 	struct lmk_event *event;
 	int res;
 	long rss_in_pages = -1;
 	char taskname[MAX_TASKNAME];
 	struct mm_struct *mm = get_task_mm(selected);

 	if (mm) {
 		rss_in_pages = get_mm_rss(mm);
 		mmput(mm);
 	}

 	res = get_cmdline(selected, taskname, MAX_TASKNAME - 1);

 	/* No valid process name means this is definitely not associated with a
 	 * userspace activity.
 	 */

 	if (res <= 0 || res >= MAX_TASKNAME)
 		return;

 	taskname[res] = '\0';

 	spin_lock(&lmk_event_lock);

 	head = event_buffer.head;
 	tail = READ_ONCE(event_buffer.tail);

 	/* Do not continue to log if no space remains in the buffer. */
 	if (CIRC_SPACE(head, tail, MAX_BUFFERED_EVENTS) < 1) {
 		spin_unlock(&lmk_event_lock);
 		return;
 	}

 	events = (struct lmk_event *) event_buffer.buf;
 	event = &events[head];

 	memcpy(event->taskname, taskname, res + 1);

 	event->pid = selected->pid;
 	event->uid = from_kuid_munged(current_user_ns(), task_uid(selected));
 	if (selected->group_leader)
 		event->group_leader_pid = selected->group_leader->pid;
 	else
 		event->group_leader_pid = -1;
 	event->min_flt = selected->min_flt;
 	event->maj_flt = selected->maj_flt;
 	event->oom_score_adj = selected->signal->oom_score_adj;
 	event->start_time = nsec_to_clock_t(selected->real_start_time);
 	event->rss_in_pages = rss_in_pages;
 	event->min_score_adj = min_score_adj;

 	event_buffer.head = (head + 1) & (MAX_BUFFERED_EVENTS - 1);

 	spin_unlock(&lmk_event_lock);

 	wake_up_interruptible(&event_wait);
 }

 static int lmk_event_show(struct seq_file *s, void *unused)
 {
 	struct lmk_event *events = (struct lmk_event *) event_buffer.buf;
 	int head;
 	int tail;
 	struct lmk_event *event;

 	spin_lock(&lmk_event_lock);

 	head = event_buffer.head;
 	tail = event_buffer.tail;

 	if (head == tail) {
 		spin_unlock(&lmk_event_lock);
 		return -EAGAIN;
 	}

 	event = &events[tail];

 	seq_printf(s, "%lu %lu %lu %lu %lu %lu %hd %hd %llu\n%s\n",
 		(unsigned long) event->pid, (unsigned long) event->uid,
 		(unsigned long) event->group_leader_pid, event->min_flt,
 		event->maj_flt, event->rss_in_pages, event->oom_score_adj,
 		event->min_score_adj, event->start_time, event->taskname);

 	event_buffer.tail = (tail + 1) & (MAX_BUFFERED_EVENTS - 1);

 	spin_unlock(&lmk_event_lock);
 	return 0;
 }

 static unsigned int lmk_event_poll(struct file *file, poll_table *wait)
 {
 	int ret = 0;

 	poll_wait(file, &event_wait, wait);
 	spin_lock(&lmk_event_lock);
 	if (event_buffer.head != event_buffer.tail)
 		ret = POLLIN;
 	spin_unlock(&lmk_event_lock);
 	return ret;
 }

 static int lmk_event_open(struct inode *inode, struct file *file)
 {
 	return single_open(file, lmk_event_show, inode->i_private);
 }

 static const struct file_operations event_file_ops = {
 	.open = lmk_event_open,
 	.poll = lmk_event_poll,
 	.read = seq_read
 };

 static void lmk_event_init(void)
 {
 	struct proc_dir_entry *entry;

 	event_buffer.head = 0;
 	event_buffer.tail = 0;
 	event_buffer.buf = kmalloc(
 		sizeof(struct lmk_event) * MAX_BUFFERED_EVENTS, GFP_KERNEL);
 	if (!event_buffer.buf)
 		return;
 	entry = proc_create("lowmemorykiller", 0, NULL, &event_file_ops);
 	if (!entry)
 		pr_err("error creating kernel lmk event file\n");
 }

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

 #ifdef CONFIG_AMLOGIC_MEMORY_EXTEND
 static unsigned long forgeround_jiffes;
 static void show_task_adj(void)
 {
 #define SHOW_PRIFIX	"score_adj:%5d, rss:%5lu"
 	struct task_struct *tsk;
 	int tasksize;

 	/* avoid print too many */
 	if (time_after(forgeround_jiffes, jiffies))
 		return;

 	forgeround_jiffes = jiffies + HZ * 5;
 	show_mem(0);
 	lowmem_print(1, "Foreground task killed, show all Candidates\n");
 	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;
 		oom_score_adj = p->signal->oom_score_adj;
 		tasksize = get_mm_rss(p->mm);
 		task_unlock(p);
 	#ifdef CONFIG_ZRAM
 		lowmem_print(1, SHOW_PRIFIX ", rswap:%5lu, task:%5d, %s\n",
 			     oom_score_adj, get_mm_rss(p->mm),
 			     get_mm_counter(p->mm, MM_SWAPENTS),
 			     p->pid, p->comm);
 	#else
 		lowmem_print(1, SHOW_PRIFIX ", task:%5d, %s\n",
 			     oom_score_adj, get_mm_rss(p->mm),
 			     p->pid, p->comm);
 	#endif /* CONFIG_ZRAM */
 	}
 }
 #endif /* CONFIG_AMLOGIC_MEMORY_EXTEND */

 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);
 #ifdef CONFIG_ANDROID_LOW_MEMORY_KILLER_USE_MEM_AVAILABLE
 	int other_free = si_mem_available();
 #else
 	int other_free = global_page_state(NR_FREE_PAGES) - totalreserve_pages;
 #endif /* CONFIG_ANDROID_LOW_MEMORY_KILLER_USE_MEM_AVAILABLE */
 	int other_file = global_node_page_state(NR_FILE_PAGES) -
 				global_node_page_state(NR_SHMEM) -
 				global_node_page_state(NR_UNEVICTABLE) -
 				total_swapcache_pages();
 #ifdef CONFIG_AMLOGIC_CMA
 	int free_cma   = 0;
 	int file_cma   = 0;
 	int cma_forbid = 0;

 	if (cma_forbidden_mask(sc->gfp_mask) && !current_is_kswapd()) {
 		free_cma    = global_page_state(NR_FREE_CMA_PAGES);
 		file_cma    = global_page_state(NR_INACTIVE_FILE_CMA) +
 			      global_page_state(NR_ACTIVE_FILE_CMA);
 		other_free -= free_cma;
 		other_file -= file_cma;
 		cma_forbid  = 1;
 	}
 #endif /* CONFIG_AMLOGIC_CMA */

 	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) {
 		long cache_size = other_file * (long)(PAGE_SIZE / 1024);
 		long cache_limit = minfree * (long)(PAGE_SIZE / 1024);
 		long free = other_free * (long)(PAGE_SIZE / 1024);

 		task_lock(selected);
 		send_sig(SIGKILL, selected, 0);
 		if (selected->mm)
 			task_set_lmk_waiting(selected);
 		task_unlock(selected);
 		trace_lowmemory_kill(selected, cache_size, cache_limit, free);
 		lowmem_print(1, "Killing '%s' (%d) (tgid %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->tgid,
 			     selected_oom_score_adj,
 			     selected_tasksize * (long)(PAGE_SIZE / 1024),
 			     current->comm, current->pid,
 			     cache_size, cache_limit,
 			     min_score_adj,
 			     free);
 	#ifdef CONFIG_AMLOGIC_CMA
 		if (cma_forbid) {
 			/* kill quickly if can't use cma */
 			lowmem_deathpending_timeout = jiffies + HZ / 2;
 			pr_info("   Free cma:%ldkB, file cma:%ldkB\n",
 				free_cma * (long)(PAGE_SIZE / 1024),
 				file_cma * (long)(PAGE_SIZE / 1024));
 		} else {
 			lowmem_deathpending_timeout = jiffies + HZ;
 		}
 	#else
 		lowmem_deathpending_timeout = jiffies + HZ;
 	#endif /* CONFIG_AMLOGIC_CMA */
 		rem += selected_tasksize;
 	#ifdef CONFIG_AMLOGIC_MEMORY_EXTEND
 		show_task_adj();
 	#endif /* CONFIG_AMLOGIC_MEMORY_EXTEND */
 	}

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

 	if (selected)
 		handle_lmk_event(selected, min_score_adj);

 	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);
 	lmk_event_init();
 	return 0;
 }
 device_initcall(lowmem_init);

 #ifdef CONFIG_ANDROID_LOW_MEMORY_KILLER_AUTODETECT_OOM_ADJ_VALUES
 static short lowmem_oom_adj_to_oom_score_adj(short oom_adj)
 {
 	if (oom_adj == OOM_ADJUST_MAX)
 		return OOM_SCORE_ADJ_MAX;
 	else
 		return (oom_adj * OOM_SCORE_ADJ_MAX) / -OOM_DISABLE;
 }

 static void lowmem_autodetect_oom_adj_values(void)
 {
 	int i;
 	short oom_adj;
 	short oom_score_adj;
 	int array_size = ARRAY_SIZE(lowmem_adj);

 	if (lowmem_adj_size < array_size)
 		array_size = lowmem_adj_size;

 	if (array_size <= 0)
 		return;

 	oom_adj = lowmem_adj[array_size - 1];
 	if (oom_adj > OOM_ADJUST_MAX)
 		return;

 	oom_score_adj = lowmem_oom_adj_to_oom_score_adj(oom_adj);
 	if (oom_score_adj <= OOM_ADJUST_MAX)
 		return;

 	lowmem_print(1, "lowmem_shrink: convert oom_adj to oom_score_adj:\n");
 	for (i = 0; i < array_size; i++) {
 		oom_adj = lowmem_adj[i];
 		oom_score_adj = lowmem_oom_adj_to_oom_score_adj(oom_adj);
 		lowmem_adj[i] = oom_score_adj;
 		lowmem_print(1, "oom_adj %d => oom_score_adj %d\n",
 			     oom_adj, oom_score_adj);
 	}
 }

 static int lowmem_adj_array_set(const char *val, const struct kernel_param *kp)
 {
 	int ret;

 	ret = param_array_ops.set(val, kp);

 	/* HACK: Autodetect oom_adj values in lowmem_adj array */
 	lowmem_autodetect_oom_adj_values();

 	return ret;
 }

 static int lowmem_adj_array_get(char *buffer, const struct kernel_param *kp)
 {
 	return param_array_ops.get(buffer, kp);
 }

 static void lowmem_adj_array_free(void *arg)
 {
 	param_array_ops.free(arg);
 }

 static struct kernel_param_ops lowmem_adj_array_ops = {
 	.set = lowmem_adj_array_set,
 	.get = lowmem_adj_array_get,
 	.free = lowmem_adj_array_free,
 };

 static const struct kparam_array __param_arr_adj = {
 	.max = ARRAY_SIZE(lowmem_adj),
 	.num = &lowmem_adj_size,
 	.ops = &param_ops_short,
 	.elemsize = sizeof(lowmem_adj[0]),
 	.elem = lowmem_adj,
 };
 #endif

 /*
  * 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, 0644);
 #ifdef CONFIG_ANDROID_LOW_MEMORY_KILLER_AUTODETECT_OOM_ADJ_VALUES
 module_param_cb(adj, &lowmem_adj_array_ops,
 		.arr = &__param_arr_adj,
 		0644);
 __MODULE_PARM_TYPE(adj, "array of short");
 #else
 module_param_array_named(adj, lowmem_adj, short, &lowmem_adj_size, 0644);
 #endif
 module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
 			 0644);
 module_param_named(debug_level, lowmem_debug_level, uint, 0644);
	/* 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>
	#include <linux/circ_buf.h>
	#include <linux/proc_fs.h>
	#include <linux/slab.h>
	#include <linux/poll.h>

	#ifdef CONFIG_AMLOGIC_CMA
	#include <linux/amlogic/aml_cma.h>
	#endif

	#define CREATE_TRACE_POINTS
	#include "trace/lowmemorykiller.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 DECLARE_WAIT_QUEUE_HEAD(event_wait);
	static DEFINE_SPINLOCK(lmk_event_lock);
	static struct circ_buf event_buffer;
	#define MAX_BUFFERED_EVENTS 8
	#define MAX_TASKNAME 128

	struct lmk_event {
	char taskname[MAX_TASKNAME];
	pid_t pid;
	uid_t uid;
	pid_t group_leader_pid;
	unsigned long min_flt;
	unsigned long maj_flt;
	unsigned long rss_in_pages;
	short oom_score_adj;
	short min_score_adj;
	unsigned long long start_time;
	struct list_head list;
	};

	void handle_lmk_event(struct task_struct *selected, short min_score_adj)
	{
	int head;
	int tail;
	struct lmk_event *events;
	struct lmk_event *event;
	int res;
	long rss_in_pages = -1;
	char taskname[MAX_TASKNAME];
	struct mm_struct *mm = get_task_mm(selected);

	if (mm) {
	rss_in_pages = get_mm_rss(mm);
	mmput(mm);
	}

	res = get_cmdline(selected, taskname, MAX_TASKNAME - 1);

	/* No valid process name means this is definitely not associated with a
	* userspace activity.
	*/

	if (res <= 0 \|\| res >= MAX_TASKNAME)
	return;

	taskname[res] = '\0';

	spin_lock(&lmk_event_lock);

	head = event_buffer.head;
	tail = READ_ONCE(event_buffer.tail);

	/* Do not continue to log if no space remains in the buffer. */
	if (CIRC_SPACE(head, tail, MAX_BUFFERED_EVENTS) < 1) {
	spin_unlock(&lmk_event_lock);
	return;
	}

	events = (struct lmk_event *) event_buffer.buf;
	event = &events[head];

	memcpy(event->taskname, taskname, res + 1);

	event->pid = selected->pid;
	event->uid = from_kuid_munged(current_user_ns(), task_uid(selected));
	if (selected->group_leader)
	event->group_leader_pid = selected->group_leader->pid;
	else
	event->group_leader_pid = -1;
	event->min_flt = selected->min_flt;
	event->maj_flt = selected->maj_flt;
	event->oom_score_adj = selected->signal->oom_score_adj;
	event->start_time = nsec_to_clock_t(selected->real_start_time);
	event->rss_in_pages = rss_in_pages;
	event->min_score_adj = min_score_adj;

	event_buffer.head = (head + 1) & (MAX_BUFFERED_EVENTS - 1);

	spin_unlock(&lmk_event_lock);

	wake_up_interruptible(&event_wait);
	}

	static int lmk_event_show(struct seq_file s, void unused)
	{
	struct lmk_event events = (struct lmk_event ) event_buffer.buf;
	int head;
	int tail;
	struct lmk_event *event;

	spin_lock(&lmk_event_lock);

	head = event_buffer.head;
	tail = event_buffer.tail;

	if (head == tail) {
	spin_unlock(&lmk_event_lock);
	return -EAGAIN;
	}

	event = &events[tail];

	seq_printf(s, "%lu %lu %lu %lu %lu %lu %hd %hd %llu\n%s\n",
	(unsigned long) event->pid, (unsigned long) event->uid,
	(unsigned long) event->group_leader_pid, event->min_flt,
	event->maj_flt, event->rss_in_pages, event->oom_score_adj,
	event->min_score_adj, event->start_time, event->taskname);

	event_buffer.tail = (tail + 1) & (MAX_BUFFERED_EVENTS - 1);

	spin_unlock(&lmk_event_lock);
	return 0;
	}

	static unsigned int lmk_event_poll(struct file file, poll_table wait)
	{
	int ret = 0;

	poll_wait(file, &event_wait, wait);
	spin_lock(&lmk_event_lock);
	if (event_buffer.head != event_buffer.tail)
	ret = POLLIN;
	spin_unlock(&lmk_event_lock);
	return ret;
	}

	static int lmk_event_open(struct inode inode, struct file file)
	{
	return single_open(file, lmk_event_show, inode->i_private);
	}

	static const struct file_operations event_file_ops = {
	.open = lmk_event_open,
	.poll = lmk_event_poll,
	.read = seq_read
	};

	static void lmk_event_init(void)
	{
	struct proc_dir_entry *entry;

	event_buffer.head = 0;
	event_buffer.tail = 0;
	event_buffer.buf = kmalloc(
	sizeof(struct lmk_event) * MAX_BUFFERED_EVENTS, GFP_KERNEL);
	if (!event_buffer.buf)
	return;
	entry = proc_create("lowmemorykiller", 0, NULL, &event_file_ops);
	if (!entry)
	pr_err("error creating kernel lmk event file\n");
	}

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

	#ifdef CONFIG_AMLOGIC_MEMORY_EXTEND
	static unsigned long forgeround_jiffes;
	static void show_task_adj(void)
	{
	#define SHOW_PRIFIX "score_adj:%5d, rss:%5lu"
	struct task_struct *tsk;
	int tasksize;

	/* avoid print too many */
	if (time_after(forgeround_jiffes, jiffies))
	return;

	forgeround_jiffes = jiffies + HZ * 5;
	show_mem(0);
	lowmem_print(1, "Foreground task killed, show all Candidates\n");
	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;
	oom_score_adj = p->signal->oom_score_adj;
	tasksize = get_mm_rss(p->mm);
	task_unlock(p);
	#ifdef CONFIG_ZRAM
	lowmem_print(1, SHOW_PRIFIX ", rswap:%5lu, task:%5d, %s\n",
	oom_score_adj, get_mm_rss(p->mm),
	get_mm_counter(p->mm, MM_SWAPENTS),
	p->pid, p->comm);
	#else
	lowmem_print(1, SHOW_PRIFIX ", task:%5d, %s\n",
	oom_score_adj, get_mm_rss(p->mm),
	p->pid, p->comm);
	#endif /* CONFIG_ZRAM */
	}
	}
	#endif /* CONFIG_AMLOGIC_MEMORY_EXTEND */

	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);
	#ifdef CONFIG_ANDROID_LOW_MEMORY_KILLER_USE_MEM_AVAILABLE
	int other_free = si_mem_available();
	#else
	int other_free = global_page_state(NR_FREE_PAGES) - totalreserve_pages;
	#endif /* CONFIG_ANDROID_LOW_MEMORY_KILLER_USE_MEM_AVAILABLE */
	int other_file = global_node_page_state(NR_FILE_PAGES) -
	global_node_page_state(NR_SHMEM) -
	global_node_page_state(NR_UNEVICTABLE) -
	total_swapcache_pages();
	#ifdef CONFIG_AMLOGIC_CMA
	int free_cma = 0;
	int file_cma = 0;
	int cma_forbid = 0;

	if (cma_forbidden_mask(sc->gfp_mask) && !current_is_kswapd()) {
	free_cma = global_page_state(NR_FREE_CMA_PAGES);
	file_cma = global_page_state(NR_INACTIVE_FILE_CMA) +
	global_page_state(NR_ACTIVE_FILE_CMA);
	other_free -= free_cma;
	other_file -= file_cma;
	cma_forbid = 1;
	}
	#endif /* CONFIG_AMLOGIC_CMA */

	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) {
	long cache_size = other_file * (long)(PAGE_SIZE / 1024);
	long cache_limit = minfree * (long)(PAGE_SIZE / 1024);
	long free = other_free * (long)(PAGE_SIZE / 1024);

	task_lock(selected);
	send_sig(SIGKILL, selected, 0);
	if (selected->mm)
	task_set_lmk_waiting(selected);
	task_unlock(selected);
	trace_lowmemory_kill(selected, cache_size, cache_limit, free);
	lowmem_print(1, "Killing '%s' (%d) (tgid %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->tgid,
	selected_oom_score_adj,
	selected_tasksize * (long)(PAGE_SIZE / 1024),
	current->comm, current->pid,
	cache_size, cache_limit,
	min_score_adj,
	free);
	#ifdef CONFIG_AMLOGIC_CMA
	if (cma_forbid) {
	/* kill quickly if can't use cma */
	lowmem_deathpending_timeout = jiffies + HZ / 2;
	pr_info(" Free cma:%ldkB, file cma:%ldkB\n",
	free_cma * (long)(PAGE_SIZE / 1024),
	file_cma * (long)(PAGE_SIZE / 1024));
	} else {
	lowmem_deathpending_timeout = jiffies + HZ;
	}
	#else
	lowmem_deathpending_timeout = jiffies + HZ;
	#endif /* CONFIG_AMLOGIC_CMA */
	rem += selected_tasksize;
	#ifdef CONFIG_AMLOGIC_MEMORY_EXTEND
	show_task_adj();
	#endif /* CONFIG_AMLOGIC_MEMORY_EXTEND */
	}

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

	if (selected)
	handle_lmk_event(selected, min_score_adj);

	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);
	lmk_event_init();
	return 0;
	}
	device_initcall(lowmem_init);

	#ifdef CONFIG_ANDROID_LOW_MEMORY_KILLER_AUTODETECT_OOM_ADJ_VALUES
	static short lowmem_oom_adj_to_oom_score_adj(short oom_adj)
	{
	if (oom_adj == OOM_ADJUST_MAX)
	return OOM_SCORE_ADJ_MAX;
	else
	return (oom_adj * OOM_SCORE_ADJ_MAX) / -OOM_DISABLE;
	}

	static void lowmem_autodetect_oom_adj_values(void)
	{
	int i;
	short oom_adj;
	short oom_score_adj;
	int array_size = ARRAY_SIZE(lowmem_adj);

	if (lowmem_adj_size < array_size)
	array_size = lowmem_adj_size;

	if (array_size <= 0)
	return;

	oom_adj = lowmem_adj[array_size - 1];
	if (oom_adj > OOM_ADJUST_MAX)
	return;

	oom_score_adj = lowmem_oom_adj_to_oom_score_adj(oom_adj);
	if (oom_score_adj <= OOM_ADJUST_MAX)
	return;

	lowmem_print(1, "lowmem_shrink: convert oom_adj to oom_score_adj:\n");
	for (i = 0; i < array_size; i++) {
	oom_adj = lowmem_adj[i];
	oom_score_adj = lowmem_oom_adj_to_oom_score_adj(oom_adj);
	lowmem_adj[i] = oom_score_adj;
	lowmem_print(1, "oom_adj %d => oom_score_adj %d\n",
	oom_adj, oom_score_adj);
	}
	}

	static int lowmem_adj_array_set(const char val, const struct kernel_param kp)
	{
	int ret;

	ret = param_array_ops.set(val, kp);

	/* HACK: Autodetect oom_adj values in lowmem_adj array */
	lowmem_autodetect_oom_adj_values();

	return ret;
	}

	static int lowmem_adj_array_get(char buffer, const struct kernel_param kp)
	{
	return param_array_ops.get(buffer, kp);
	}

	static void lowmem_adj_array_free(void *arg)
	{
	param_array_ops.free(arg);
	}

	static struct kernel_param_ops lowmem_adj_array_ops = {
	.set = lowmem_adj_array_set,
	.get = lowmem_adj_array_get,
	.free = lowmem_adj_array_free,
	};

	static const struct kparam_array __param_arr_adj = {
	.max = ARRAY_SIZE(lowmem_adj),
	.num = &lowmem_adj_size,
	.ops = &param_ops_short,
	.elemsize = sizeof(lowmem_adj[0]),
	.elem = lowmem_adj,
	};
	#endif

	/*
	* 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, 0644);
	#ifdef CONFIG_ANDROID_LOW_MEMORY_KILLER_AUTODETECT_OOM_ADJ_VALUES
	module_param_cb(adj, &lowmem_adj_array_ops,
	.arr = &__param_arr_adj,
	0644);
	__MODULE_PARM_TYPE(adj, "array of short");
	#else
	module_param_array_named(adj, lowmem_adj, short, &lowmem_adj_size, 0644);
	#endif
	module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
	0644);
	module_param_named(debug_level, lowmem_debug_level, uint, 0644);