Lowmem: port from slp kernel

Port lsp lowmem code to PR3, only did a little changes. That is change
rss in task_rss_t to long and use atomic_long_read to get atomic_long_t
value.

Change-Id: I32173900b3866f324ea81d7f47b8984f7ec17ba6
Signed-off-by: Chengwei Yang <chengwei.yang@intel.com>

5 files changed, 749 insertions, 0 deletions

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 40612b3bd91..8e6f60fe5f5 100755
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -581,6 +581,12 @@ config UUID
 	---help---
 	 Driver for get UUID.
 
+config SLP_LOWMEM_NOTIFY
+        bool "Driver for SLP Low Memory Notification"
+        default n
+        help
+        Provide interface to register for low memory notifications.
+
 source "drivers/misc/c2port/Kconfig"
 source "drivers/misc/eeprom/Kconfig"
 source "drivers/misc/cb710/Kconfig"
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 96abca66900..fb918aabb38 100755
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -60,3 +60,4 @@ obj-$(CONFIG_MID_I2S_DEV)	+= mid_i2s_dev/
 obj-$(CONFIG_EMMC_IPANIC)	+= emmc_ipanic.o
 obj-$(CONFIG_SCU_LOGGING)	+= intel_fabric_logging.o
 obj-$(CONFIG_UUID)	+= uuid.o
+obj-$(CONFIG_SLP_LOWMEM_NOTIFY) += slp_lowmem_notify.o
diff --git a/drivers/misc/slp_lowmem_notify.c b/drivers/misc/slp_lowmem_notify.c
new file mode 100644
index 00000000000..f5c1d29d69e
--- /dev/null
+++ b/drivers/misc/slp_lowmem_notify.c
@@ -0,0 +1,700 @@
+/*
+ *
+ * Copyright (C) 2008-2009 Palm, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+/*
+ * [NOTICE]
+ * modified by Baik - Samsung
+ * this module must examine about license.
+ * If SAMSUNG have a problem with the license, we must re-program module for
+ * low memory notification.
+ */
+
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+
+#include <linux/mm.h>
+#include <linux/oom.h>
+#include <linux/swap.h>
+#include <linux/vmstat.h>
+#include <linux/hugetlb.h>
+
+#include <linux/sched.h>
+
+#include <linux/spinlock.h>
+#include <linux/poll.h>
+#include <linux/wait.h>
+#include <linux/shmem_fs.h>
+
+#include <asm/atomic.h>
+
+#include <linux/slp_lowmem_notify.h>
+
+#if (LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 28))
+#error "You should need higher version of kernel"
+#endif
+
+#define MB(pages) ((K(pages))/1024)
+#define K(pages) ((pages) << (PAGE_SHIFT - 10))
+
+struct memnotify_file_info {
+	int last_threshold;
+	struct file *file;
+	unsigned int nr_events;
+};
+
+static DECLARE_WAIT_QUEUE_HEAD(memnotify_wait);
+static atomic_t nr_watcher_task = ATOMIC_INIT(0);
+
+#define NR_MEMNOTIFY_LEVEL 4
+
+enum {
+	THRESHOLD_NORMAL,
+	THRESHOLD_LOW,
+	THRESHOLD_CRITICAL,
+	THRESHOLD_DEADLY,
+};
+
+static const char *_threshold_string[NR_MEMNOTIFY_LEVEL] = {
+	"normal  ",
+	"low     ",
+	"critical",
+	"deadly  ",
+};
+
+static const char *threshold_string(int threshold)
+{
+	if (threshold > ARRAY_SIZE(_threshold_string))
+		return "";
+
+	return _threshold_string[threshold];
+}
+
+static unsigned long memnotify_messages[NR_MEMNOTIFY_LEVEL] = {
+	MEMNOTIFY_NORMAL,	/* The happy state */
+	MEMNOTIFY_LOW,		/* Userspace drops uneeded memory. - example : malloc_trim */
+	MEMNOTIFY_CRITICAL,	/* Userspace OOM Killer */
+	MEMNOTIFY_DEADLY,	/* Critical point.. if happend, kill victims by kernel */
+};
+
+static atomic_t memnotify_last_threshold = ATOMIC_INIT(THRESHOLD_NORMAL);
+
+static size_t memnotify_enter_thresholds[NR_MEMNOTIFY_LEVEL] = {
+	INT_MAX,
+	25,
+	20,
+	19,
+};
+
+static size_t memnotify_leave_thresholds[NR_MEMNOTIFY_LEVEL] = {
+	INT_MAX,
+	26,
+	26,
+	26,
+};
+
+static inline unsigned long memnotify_get_reclaimable(void)
+{
+	return global_page_state(NR_ACTIVE_FILE) +
+	    global_page_state(NR_INACTIVE_FILE) +
+	    global_page_state(NR_SLAB_RECLAIMABLE);
+}
+
+static inline unsigned long memnotify_get_used(void)
+{
+	return totalram_pages - memnotify_get_reclaimable() -
+	    global_page_state(NR_FREE_PAGES);
+}
+
+static inline unsigned long memnotify_get_total(void)
+{
+	return totalram_pages;
+}
+
+#define OOMADJ_OF(p)	(p->signal->oom_adj)
+
+static int memnotify_victim_task(int force_kill, gfp_t gfp_mask)
+{
+	struct task_struct *p;
+	struct task_struct *selected = NULL;
+	int tasksize;
+	int selected_tasksize = 0;
+	int total_selected_tasksize = 0;
+	int ret_pid = -1;
+
+	read_lock(&tasklist_lock);
+	for_each_process(p) {
+		if (!p->mm)
+			continue;
+		if (OOMADJ_OF(p) == OOM_DISABLE)	/* OOM_DISABLE skip */
+			continue;
+		if ((total_selected_tasksize * PAGE_SIZE) >
+		    memnotify_leave_thresholds[THRESHOLD_LOW]
+		    * 1024 * 1024) {	/* MB to byte */
+			read_unlock(&tasklist_lock);
+			return -1;
+		}
+		if (test_tsk_thread_flag(p, TIF_MEMDIE)) {
+			total_selected_tasksize += get_mm_rss(p->mm);
+			continue;
+		}
+
+		tasksize = get_mm_rss(p->mm);
+		if (tasksize > 0 &&
+		    !(p->state & TASK_UNINTERRUPTIBLE) &&
+		    (selected == NULL || OOMADJ_OF(p) > OOMADJ_OF(selected)
+		     || (OOMADJ_OF(p) == OOMADJ_OF(selected) &&
+			 tasksize > selected_tasksize))) {
+			selected = p;
+			selected_tasksize = tasksize;
+		}
+	}
+	read_unlock(&tasklist_lock);
+
+	if (selected != NULL && force_kill) {
+		pr_crit("[SELECTED] send sigkill to %d (%s),"
+			" adj %d, size %lu Byte(s)\n",
+			selected->pid, selected->comm,
+			OOMADJ_OF(selected), selected_tasksize * PAGE_SIZE);
+		set_tsk_thread_flag(selected, TIF_MEMDIE);
+		force_sig(SIGKILL, selected);
+		ret_pid = 0;
+		/*
+		 * Give "p" a good chance of killing itself before we
+		 * retry to allocate memory unless "p" is current
+		 */
+		if (!test_thread_flag(TIF_MEMDIE) && (gfp_mask & __GFP_WAIT))
+			schedule_timeout_uninterruptible(1);
+	} else if (selected == NULL) {
+		pr_crit("No Victim !!!\n");
+	} else {		/* (selected != NULL && force_kill == 0) */
+		pr_crit("Victim task is pid %d (%s),"
+			" adj %d, size %lu Byte(s)\n",
+			selected->pid,
+			selected->comm,
+			OOMADJ_OF(selected), selected_tasksize * PAGE_SIZE);
+		ret_pid = selected->pid;
+	}
+
+	return ret_pid;
+}
+
+static struct task_rss_t
+{
+	pid_t pid;
+	char comm[TASK_COMM_LEN];
+	long rss;
+} task_rss[256];		/* array for tasks and rss info */
+static int nr_tasks;		/* number of tasks to be stored */
+static int check_peak;		/* flag to store the rss or not */
+static long old_real_free;	/* last minimum of free memory size */
+
+static void save_task_rss(void)
+{
+	struct task_struct *p;
+	int i;
+
+	nr_tasks = 0;
+	read_lock(&tasklist_lock);
+	for_each_process(p) {
+		if (!p->mm)
+			continue;
+		task_rss[nr_tasks].pid = p->pid ;
+		strncpy(task_rss[nr_tasks].comm, p->comm,
+				sizeof(task_rss[nr_tasks].comm));
+		task_rss[nr_tasks].rss = 0;
+		//atomic_long_set(&task_rss[nr_tasks].rss, 0);
+
+		/* If except pages in swap, use get_mm_rss() */
+		for (i = 0; i < NR_MM_COUNTERS; i++)
+			//atomic_long_add(atomic_long_read(&p->mm->rss_stat.count[i]), &task_rss[nr_tasks].rss);
+			task_rss[nr_tasks].rss += atomic_long_read(&p->mm->rss_stat.count[i]);
+
+		if ((++nr_tasks) > sizeof(task_rss))
+			break;
+	}
+	read_unlock(&tasklist_lock);
+}
+
+static void memnotify_wakeup(int threshold)
+{
+	atomic_set(&memnotify_last_threshold, threshold);
+	wake_up_interruptible_all(&memnotify_wait);
+}
+
+int memnotify_threshold(gfp_t gfp_mask)
+{
+	long reclaimable, real_free;
+	int threshold;
+	int last_threshold;
+	int i;
+
+	real_free = MB(global_page_state(NR_FREE_PAGES));
+	reclaimable = MB(memnotify_get_reclaimable());
+	threshold = THRESHOLD_NORMAL;
+	last_threshold = atomic_read(&memnotify_last_threshold);
+
+	/* we save the tasks and rss info when free memory size is minimum,
+	 * which means total used memory is highest at that moment. */
+	if (check_peak && (old_real_free > real_free)) {
+		old_real_free = real_free;
+		save_task_rss();
+	}
+
+	/* Obtain enter threshold level */
+	for (i = (NR_MEMNOTIFY_LEVEL - 1); i >= 0; i--) {
+		if (real_free < memnotify_enter_thresholds[i] &&
+		    reclaimable < memnotify_enter_thresholds[i]) {
+			threshold = i;
+			break;
+		}
+	}
+	/* return quickly when normal case */
+	if (likely(threshold == THRESHOLD_NORMAL &&
+		   last_threshold == THRESHOLD_NORMAL))
+		return 0;
+
+	/* Need to leave a threshold by a certain margin. */
+	if (threshold < last_threshold) {
+		int leave_threshold =
+		    memnotify_leave_thresholds[last_threshold];
+
+		if (real_free < leave_threshold &&
+		    reclaimable < leave_threshold) {
+			threshold = last_threshold;
+		}
+	}
+
+	if (unlikely(threshold == THRESHOLD_DEADLY)) {
+		pr_crit("<< System memory is VERY LOW - %ld MB, %d(%s)>>\n",
+			(real_free + reclaimable), current->pid, current->comm);
+		memnotify_victim_task(true, gfp_mask);
+		return 0;
+	} else if (last_threshold == threshold)
+		return 0;
+
+	/* Rate limited notification of threshold changes. */
+	memnotify_wakeup(threshold);
+
+	return 0;
+}
+EXPORT_SYMBOL(memnotify_threshold);
+
+static int lowmemnotify_open(struct inode *inode, struct file *file)
+{
+	struct memnotify_file_info *info;
+	int err = 0;
+
+	info = kmalloc(sizeof(*info), GFP_KERNEL);
+	if (!info) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	info->file = file;
+	info->nr_events = 0;
+	file->private_data = info;
+	atomic_inc(&nr_watcher_task);
+out:
+	return err;
+}
+
+static int lowmemnotify_release(struct inode *inode, struct file *file)
+{
+	struct memnotify_file_info *info = file->private_data;
+
+	kfree(info);
+	atomic_dec(&nr_watcher_task);
+	return 0;
+}
+
+static unsigned int lowmemnotify_poll(struct file *file, poll_table *wait)
+{
+	unsigned int retval = 0;
+	struct memnotify_file_info *info = file->private_data;
+	int threshold;
+
+	poll_wait(file, &memnotify_wait, wait);
+
+	threshold = atomic_read(&memnotify_last_threshold);
+
+	if (info->last_threshold != threshold) {
+		info->last_threshold = threshold;
+		retval = POLLIN;
+		info->nr_events++;
+
+		pr_info("%s (%d%%, Used %ldMB, Free %ldMB, Reclaimable"
+				" %ldMB, %s)\n",
+				__func__,
+				(int)(MB(memnotify_get_used()) * 100
+					/ MB(memnotify_get_total())),
+				MB(memnotify_get_used()),
+				MB(global_page_state(NR_FREE_PAGES)),
+				MB(memnotify_get_reclaimable()),
+				threshold_string(threshold));
+
+	} else if(info->nr_events > 0)
+		retval = POLLIN;
+
+	return retval;
+}
+
+static ssize_t lowmemnotify_read(struct file *file,
+				 char __user *buf, size_t count, loff_t *ppos)
+{
+	int threshold;
+	unsigned long data;
+	ssize_t ret = 0;
+	struct memnotify_file_info *info = file->private_data;
+
+	if (count < sizeof(unsigned long))
+		return -EINVAL;
+
+	threshold = atomic_read(&memnotify_last_threshold);
+	data = memnotify_messages[threshold];
+
+	ret = put_user(data, (unsigned long __user *)buf);
+	if (0 == ret) {
+		ret = sizeof(unsigned long);
+		info->nr_events = 0;
+	}
+	return ret;
+}
+
+static ssize_t meminfo_show(struct class *class, struct class_attribute *attr,
+			    char *buf)
+{
+	unsigned long used;
+	unsigned long total_mem;
+	int used_ratio;
+
+	int last_threshold;
+
+	int len = 0;
+	int i;
+
+	used = memnotify_get_used();
+	total_mem = memnotify_get_total();
+
+	last_threshold = atomic_read(&memnotify_last_threshold);
+
+	used_ratio = used * 100 / total_mem;
+
+	len += snprintf(buf + len, PAGE_SIZE,
+			"Total RAM size: \t%15ld MB( %6ld kB)\n",
+			MB(totalram_pages), K(totalram_pages));
+
+	len += snprintf(buf + len, PAGE_SIZE,
+			"Used (Mem+Swap): \t%15ld MB( %6ld kB)\n", MB(used),
+			K(used));
+
+	len +=
+	    snprintf(buf + len, PAGE_SIZE,
+		     "Used (Mem):  \t\t%15ld MB( %6ld kB)\n", MB(used),
+		     K(used));
+
+	len +=
+	    snprintf(buf + len, PAGE_SIZE,
+		     "Used (Swap): \t\t%15ld MB( %6ld kB)\n",
+		     MB(total_swap_pages - nr_swap_pages),
+		     K(total_swap_pages - nr_swap_pages));
+
+	len += snprintf(buf + len, PAGE_SIZE,
+			"Used Ratio: \t\t%15d  %%\n", used_ratio);
+
+	len +=
+	    snprintf(buf + len, PAGE_SIZE, "Mem Free:\t\t%15ld MB( %6ld kB)\n",
+		     MB((long)(global_page_state(NR_FREE_PAGES))),
+		     K((long)(global_page_state(NR_FREE_PAGES))));
+
+	len += snprintf(buf + len, PAGE_SIZE,
+			"Available (Free+Reclaimable):%10ld MB( %6ld kB)\n",
+			MB((long)(total_mem - used)),
+			K((long)(total_mem - used)));
+
+	len += snprintf(buf + len, PAGE_SIZE,
+			"Reserve Page:\t\t%15ld MB( %6ld kB)\n",
+			MB((long)(totalreserve_pages)),
+			K((long)(totalreserve_pages)));
+
+	len += snprintf(buf + len, PAGE_SIZE,
+			"Last Threshold:    \t%s\n",
+			threshold_string(last_threshold));
+
+	len += snprintf(buf + len, PAGE_SIZE,
+			"Enter Thresholds: available\t    used\n");
+	for (i = 0; i < NR_MEMNOTIFY_LEVEL; i++) {
+		unsigned long limit = MB(total_mem) -
+		    memnotify_enter_thresholds[i];
+		long left = limit - MB(used);
+		len += snprintf(buf + len, PAGE_SIZE,
+				"%s:\t%4d MB, %15ld MB, Rem: %10ld MB\n",
+				threshold_string(i),
+				memnotify_enter_thresholds[i], limit, left);
+
+	}
+	len += snprintf(buf + len, PAGE_SIZE,
+			"Leave Thresholds: available\t    used\n");
+	for (i = 0; i < NR_MEMNOTIFY_LEVEL; i++) {
+		unsigned long limit = MB(total_mem) -
+		    memnotify_leave_thresholds[i];
+		long left = limit - MB(used);
+		len += snprintf(buf + len, PAGE_SIZE,
+				"%s:\t%4d MB, %15ld MB, Rem: %10ld MB\n",
+				threshold_string(i),
+				memnotify_leave_thresholds[i], limit, left);
+	}
+
+	return len;
+}
+
+#define DEFAULT_MARGIN	5	/* MB */
+static size_t leave_margin = DEFAULT_MARGIN;
+
+ssize_t leave_margin_store(struct class *class, struct class_attribute *attr,
+			   const char *buf, size_t count)
+{
+	ssize_t ret = -EINVAL;
+	long val;
+	ret = strict_strtol(buf, 10, &val);
+	if (ret == 0) {
+		ret = count;
+		leave_margin = val;
+		val += memnotify_enter_thresholds[THRESHOLD_LOW];
+		memnotify_leave_thresholds[THRESHOLD_LOW] = val;
+		memnotify_leave_thresholds[THRESHOLD_CRITICAL] = val;
+		memnotify_leave_thresholds[THRESHOLD_DEADLY] = val;
+	}
+	return ret;
+}
+
+ssize_t threshold_lv1_store(struct class *class, struct class_attribute *attr,
+			    const char *buf, size_t count)
+{
+	ssize_t ret = -EINVAL;
+	long val;
+	ret = strict_strtol(buf, 10, &val);
+	if (ret == 0) {
+		ret = count;
+		memnotify_enter_thresholds[THRESHOLD_LOW] = val;
+		/* set leave thresholds with the margin */
+		val += leave_margin;
+		memnotify_leave_thresholds[THRESHOLD_LOW] = val;
+		memnotify_leave_thresholds[THRESHOLD_CRITICAL] = val;
+		memnotify_leave_thresholds[THRESHOLD_DEADLY] = val;
+	}
+	return ret;
+}
+
+ssize_t threshold_lv2_store(struct class *class, struct class_attribute *attr,
+			    const char *buf, size_t count)
+{
+	ssize_t ret = -EINVAL;
+	long val;
+	ret = strict_strtol(buf, 10, &val);
+	if (ret == 0) {
+		ret = count;
+		memnotify_enter_thresholds[THRESHOLD_CRITICAL] = val;
+	}
+	return ret;
+}
+
+static ssize_t victim_task_show(struct class *class,
+				struct class_attribute *attr, char *buf)
+{
+	int pid;
+	int len = 0;
+	int *intbuf;
+
+	pid = memnotify_victim_task(false, 0);
+
+	intbuf = (int *)buf;
+	*intbuf = pid;
+	len = sizeof(int);
+
+	return len;
+}
+
+static ssize_t peak_rss_show(struct class *class,
+				struct class_attribute *attr, char *buf)
+{
+	int len = 0;
+	int i;
+
+	len += snprintf(buf + len, PAGE_SIZE, "  PID\tRSS(KB)\t NAME\n");
+	len += snprintf(buf + len, PAGE_SIZE,
+			"=================================\n");
+	for (i = 0; i < nr_tasks; i++) {
+		len += snprintf(buf + len, PAGE_SIZE, "%5d\t%6ld\t %s\n",
+				task_rss[i].pid, K(task_rss[i].rss),
+				task_rss[i].comm);
+	}
+
+	return (ssize_t) len;
+}
+
+static ssize_t peak_rss_store(struct class *class, struct class_attribute *attr,
+			   const char *buf, size_t count)
+{
+	ssize_t ret = -EINVAL;
+	long val;
+	ret = strict_strtol(buf, 10, &val);
+	if (ret == 0) {
+		ret = count;
+		if (val) {
+			check_peak = 1;
+			save_task_rss();
+		} else {
+			check_peak = 0;
+			/* set initial free memory with total memory size */
+			old_real_free = memnotify_get_total();
+		}
+	}
+	return ret;
+}
+
+static CLASS_ATTR(meminfo, S_IRUGO, meminfo_show, NULL);
+static CLASS_ATTR(threshold_lv1, S_IWUSR, NULL, threshold_lv1_store);
+static CLASS_ATTR(threshold_lv2, S_IWUSR, NULL, threshold_lv2_store);
+static CLASS_ATTR(leave_margin, S_IWUSR, NULL, leave_margin_store);
+static CLASS_ATTR(victim_task, S_IRUGO | S_IWUSR, victim_task_show, NULL);
+static CLASS_ATTR(check_peak_rss, S_IRUGO | S_IWUSR, peak_rss_show,
+		peak_rss_store);
+
+static const struct file_operations memnotify_fops = {
+	.open = lowmemnotify_open,
+	.release = lowmemnotify_release,
+	.read = lowmemnotify_read,
+	.poll = lowmemnotify_poll,
+};
+
+static struct device *memnotify_device;
+static struct class *memnotify_class;
+static int memnotify_major = -1;
+
+static int __init lowmemnotify_init(void)
+{
+	int err;
+
+	pr_info("Low Memory Notify loaded\n");
+
+	memnotify_enter_thresholds[0] = MB(totalram_pages);
+	memnotify_leave_thresholds[0] = MB(totalram_pages);
+
+	memnotify_major = register_chrdev(0, MEMNOTIFY_DEVICE, &memnotify_fops);
+	if (memnotify_major < 0) {
+		pr_err("Unable to get major number for memnotify dev\n");
+		err = -EBUSY;
+		goto error_create_chr_dev;
+	}
+
+	memnotify_class = class_create(THIS_MODULE, MEMNOTIFY_DEVICE);
+	if (IS_ERR(memnotify_class)) {
+		err = PTR_ERR(memnotify_class);
+		goto error_class_create;
+	}
+
+	memnotify_device =
+	    device_create(memnotify_class, NULL, MKDEV(memnotify_major, 0),
+			  NULL, MEMNOTIFY_DEVICE);
+
+	if (IS_ERR(memnotify_device)) {
+		err = PTR_ERR(memnotify_device);
+		goto error_create_class_dev;
+	}
+
+	err = class_create_file(memnotify_class, &class_attr_meminfo);
+	if (err) {
+		pr_err("%s: couldn't create meminfo.\n", __func__);
+		goto error_create_meminfo_class_file;
+	}
+
+	err = class_create_file(memnotify_class, &class_attr_threshold_lv1);
+	if (err) {
+		pr_err("%s: couldn't create threshold level 1.\n", __func__);
+		goto error_create_threshold_lv1_class_file;
+	}
+
+	err = class_create_file(memnotify_class, &class_attr_threshold_lv2);
+	if (err) {
+		pr_err("%s: couldn't create threshold level 2.\n", __func__);
+		goto error_create_threshold_lv2_class_file;
+	}
+
+	err = class_create_file(memnotify_class, &class_attr_leave_margin);
+	if (err) {
+		pr_err("%s: couldn't create leave margin.\n", __func__);
+		goto error_create_leave_margin_class_file;
+	}
+
+	err = class_create_file(memnotify_class, &class_attr_victim_task);
+	if (err) {
+		pr_err("%s: couldn't create victim sysfs file.\n", __func__);
+		goto error_create_victim_task_class_file;
+	}
+
+	err = class_create_file(memnotify_class, &class_attr_check_peak_rss);
+	if (err) {
+		pr_err("%s: couldn't create peak rss sysfs file.\n", __func__);
+		goto error_create_peak_rss_class_file;
+	}
+
+	/* set initial free memory with total memory size */
+	old_real_free = memnotify_get_total();
+
+	return 0;
+
+error_create_peak_rss_class_file:
+	class_remove_file(memnotify_class, &class_attr_victim_task);
+error_create_victim_task_class_file:
+	class_remove_file(memnotify_class, &class_attr_leave_margin);
+error_create_leave_margin_class_file:
+	class_remove_file(memnotify_class, &class_attr_threshold_lv2);
+error_create_threshold_lv2_class_file:
+	class_remove_file(memnotify_class, &class_attr_threshold_lv1);
+error_create_threshold_lv1_class_file:
+	class_remove_file(memnotify_class, &class_attr_meminfo);
+error_create_meminfo_class_file:
+	device_del(memnotify_device);
+error_create_class_dev:
+	class_destroy(memnotify_class);
+error_class_create:
+	unregister_chrdev(memnotify_major, MEMNOTIFY_DEVICE);
+error_create_chr_dev:
+	return err;
+}
+
+static void __exit lowmemnotify_exit(void)
+{
+	if (memnotify_device)
+		device_del(memnotify_device);
+	if (memnotify_class)
+		class_destroy(memnotify_class);
+	if (memnotify_major >= 0)
+		unregister_chrdev(memnotify_major, MEMNOTIFY_DEVICE);
+}
+
+module_init(lowmemnotify_init);
+module_exit(lowmemnotify_exit);
+
+MODULE_LICENSE("GPL");
diff --git a/include/linux/slp_lowmem_notify.h b/include/linux/slp_lowmem_notify.h
new file mode 100644
index 00000000000..e5378273c4e
--- /dev/null
+++ b/include/linux/slp_lowmem_notify.h
@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2008-2009 Palm, Inc
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/version.h>
+
+#define MEMNOTIFY_DEVICE   "memnotify"
+
+#define MEMNOTIFY_NORMAL   0x0000
+#define MEMNOTIFY_LOW	   0xfaac
+#define MEMNOTIFY_CRITICAL 0xdead
+#define MEMNOTIFY_DEADLY   0xb00f
+
+extern int memnotify_threshold(gfp_t gfp_mask);
+
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 03d8c484d0b..f1e0a9ac8e7 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -58,6 +58,10 @@
 #include <linux/memcontrol.h>
 #include <linux/prefetch.h>
 
+#ifdef CONFIG_SLP_LOWMEM_NOTIFY
+#include <linux/slp_lowmem_notify.h>
+#endif
+
 #include <asm/tlbflush.h>
 #include <asm/div64.h>
 #include "internal.h"
@@ -2321,6 +2325,10 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
 		return NULL;
 	}
 
+#ifdef CONFIG_SLP_LOWMEM_NOTIFY
+	memnotify_threshold(gfp_mask);
+#endif
+
 	/* First allocation attempt */
 	page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, nodemask, order,
 			zonelist, high_zoneidx, ALLOC_WMARK_LOW|ALLOC_CPUSET,