diff --git a/ap/os/linux/linux-3.4.x/mm/memcontrol.c b/ap/os/linux/linux-3.4.x/mm/memcontrol.c
new file mode 100644
index 0000000..8c3dd64
--- /dev/null
+++ b/ap/os/linux/linux-3.4.x/mm/memcontrol.c
@@ -0,0 +1,5679 @@
+/* memcontrol.c - Memory Controller
+ *
+ * Copyright IBM Corporation, 2007
+ * Author Balbir Singh <balbir@linux.vnet.ibm.com>
+ *
+ * Copyright 2007 OpenVZ SWsoft Inc
+ * Author: Pavel Emelianov <xemul@openvz.org>
+ *
+ * Memory thresholds
+ * Copyright (C) 2009 Nokia Corporation
+ * Author: Kirill A. Shutemov
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ */
+
+#include <linux/res_counter.h>
+#include <linux/memcontrol.h>
+#include <linux/cgroup.h>
+#include <linux/mm.h>
+#include <linux/hugetlb.h>
+#include <linux/pagemap.h>
+#include <linux/smp.h>
+#include <linux/page-flags.h>
+#include <linux/backing-dev.h>
+#include <linux/bit_spinlock.h>
+#include <linux/rcupdate.h>
+#include <linux/limits.h>
+#include <linux/export.h>
+#include <linux/mutex.h>
+#include <linux/rbtree.h>
+#include <linux/slab.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+#include <linux/spinlock.h>
+#include <linux/eventfd.h>
+#include <linux/sort.h>
+#include <linux/fs.h>
+#include <linux/seq_file.h>
+#include <linux/vmalloc.h>
+#include <linux/mm_inline.h>
+#include <linux/page_cgroup.h>
+#include <linux/cpu.h>
+#include <linux/oom.h>
+#include "internal.h"
+#include <net/sock.h>
+#include <net/tcp_memcontrol.h>
+
+#include <asm/uaccess.h>
+
+#include <trace/events/vmscan.h>
+
+struct cgroup_subsys mem_cgroup_subsys __read_mostly;
+#define MEM_CGROUP_RECLAIM_RETRIES	5
+struct mem_cgroup *root_mem_cgroup __read_mostly;
+
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
+/* Turned on only when memory cgroup is enabled && really_do_swap_account = 1 */
+int do_swap_account __read_mostly;
+
+/* for remember boot option*/
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP_ENABLED
+static int really_do_swap_account __initdata = 1;
+#else
+static int really_do_swap_account __initdata = 0;
+#endif
+
+#else
+#define do_swap_account		(0)
+#endif
+
+
+/*
+ * Statistics for memory cgroup.
+ */
+enum mem_cgroup_stat_index {
+	/*
+	 * For MEM_CONTAINER_TYPE_ALL, usage = pagecache + rss.
+	 */
+	MEM_CGROUP_STAT_CACHE, 	   /* # of pages charged as cache */
+	MEM_CGROUP_STAT_RSS,	   /* # of pages charged as anon rss */
+	MEM_CGROUP_STAT_FILE_MAPPED,  /* # of pages charged as file rss */
+	MEM_CGROUP_STAT_SWAPOUT, /* # of pages, swapped out */
+	MEM_CGROUP_STAT_DATA, /* end of data requires synchronization */
+	MEM_CGROUP_STAT_NSTATS,
+};
+
+enum mem_cgroup_events_index {
+	MEM_CGROUP_EVENTS_PGPGIN,	/* # of pages paged in */
+	MEM_CGROUP_EVENTS_PGPGOUT,	/* # of pages paged out */
+	MEM_CGROUP_EVENTS_COUNT,	/* # of pages paged in/out */
+	MEM_CGROUP_EVENTS_PGFAULT,	/* # of page-faults */
+	MEM_CGROUP_EVENTS_PGMAJFAULT,	/* # of major page-faults */
+	MEM_CGROUP_EVENTS_NSTATS,
+};
+/*
+ * Per memcg event counter is incremented at every pagein/pageout. With THP,
+ * it will be incremated by the number of pages. This counter is used for
+ * for trigger some periodic events. This is straightforward and better
+ * than using jiffies etc. to handle periodic memcg event.
+ */
+enum mem_cgroup_events_target {
+	MEM_CGROUP_TARGET_THRESH,
+	MEM_CGROUP_TARGET_SOFTLIMIT,
+	MEM_CGROUP_TARGET_NUMAINFO,
+	MEM_CGROUP_NTARGETS,
+};
+#define THRESHOLDS_EVENTS_TARGET (128)
+#define SOFTLIMIT_EVENTS_TARGET (1024)
+#define NUMAINFO_EVENTS_TARGET	(1024)
+
+struct mem_cgroup_stat_cpu {
+	long count[MEM_CGROUP_STAT_NSTATS];
+	unsigned long events[MEM_CGROUP_EVENTS_NSTATS];
+	unsigned long targets[MEM_CGROUP_NTARGETS];
+};
+
+struct mem_cgroup_reclaim_iter {
+	/* css_id of the last scanned hierarchy member */
+	int position;
+	/* scan generation, increased every round-trip */
+	unsigned int generation;
+};
+
+/*
+ * per-zone information in memory controller.
+ */
+struct mem_cgroup_per_zone {
+	struct lruvec		lruvec;
+	unsigned long		lru_size[NR_LRU_LISTS];
+
+	struct mem_cgroup_reclaim_iter reclaim_iter[DEF_PRIORITY + 1];
+
+	struct zone_reclaim_stat reclaim_stat;
+	struct rb_node		tree_node;	/* RB tree node */
+	unsigned long long	usage_in_excess;/* Set to the value by which */
+						/* the soft limit is exceeded*/
+	bool			on_tree;
+	struct mem_cgroup	*memcg;		/* Back pointer, we cannot */
+						/* use container_of	   */
+};
+
+struct mem_cgroup_per_node {
+	struct mem_cgroup_per_zone zoneinfo[MAX_NR_ZONES];
+};
+
+struct mem_cgroup_lru_info {
+	struct mem_cgroup_per_node *nodeinfo[MAX_NUMNODES];
+};
+
+/*
+ * Cgroups above their limits are maintained in a RB-Tree, independent of
+ * their hierarchy representation
+ */
+
+struct mem_cgroup_tree_per_zone {
+	struct rb_root rb_root;
+	spinlock_t lock;
+};
+
+struct mem_cgroup_tree_per_node {
+	struct mem_cgroup_tree_per_zone rb_tree_per_zone[MAX_NR_ZONES];
+};
+
+struct mem_cgroup_tree {
+	struct mem_cgroup_tree_per_node *rb_tree_per_node[MAX_NUMNODES];
+};
+
+static struct mem_cgroup_tree soft_limit_tree __read_mostly;
+
+struct mem_cgroup_threshold {
+	struct eventfd_ctx *eventfd;
+	u64 threshold;
+};
+
+/* For threshold */
+struct mem_cgroup_threshold_ary {
+	/* An array index points to threshold just below usage. */
+	int current_threshold;
+	/* Size of entries[] */
+	unsigned int size;
+	/* Array of thresholds */
+	struct mem_cgroup_threshold entries[0];
+};
+
+struct mem_cgroup_thresholds {
+	/* Primary thresholds array */
+	struct mem_cgroup_threshold_ary *primary;
+	/*
+	 * Spare threshold array.
+	 * This is needed to make mem_cgroup_unregister_event() "never fail".
+	 * It must be able to store at least primary->size - 1 entries.
+	 */
+	struct mem_cgroup_threshold_ary *spare;
+};
+
+/* for OOM */
+struct mem_cgroup_eventfd_list {
+	struct list_head list;
+	struct eventfd_ctx *eventfd;
+};
+
+static void mem_cgroup_threshold(struct mem_cgroup *memcg);
+static void mem_cgroup_oom_notify(struct mem_cgroup *memcg);
+
+/*
+ * The memory controller data structure. The memory controller controls both
+ * page cache and RSS per cgroup. We would eventually like to provide
+ * statistics based on the statistics developed by Rik Van Riel for clock-pro,
+ * to help the administrator determine what knobs to tune.
+ *
+ * TODO: Add a water mark for the memory controller. Reclaim will begin when
+ * we hit the water mark. May be even add a low water mark, such that
+ * no reclaim occurs from a cgroup at it's low water mark, this is
+ * a feature that will be implemented much later in the future.
+ */
+struct mem_cgroup {
+	struct cgroup_subsys_state css;
+	/*
+	 * the counter to account for memory usage
+	 */
+	struct res_counter res;
+
+	union {
+		/*
+		 * the counter to account for mem+swap usage.
+		 */
+		struct res_counter memsw;
+
+		/*
+		 * rcu_freeing is used only when freeing struct mem_cgroup,
+		 * so put it into a union to avoid wasting more memory.
+		 * It must be disjoint from the css field.  It could be
+		 * in a union with the res field, but res plays a much
+		 * larger part in mem_cgroup life than memsw, and might
+		 * be of interest, even at time of free, when debugging.
+		 * So share rcu_head with the less interesting memsw.
+		 */
+		struct rcu_head rcu_freeing;
+		/*
+		 * But when using vfree(), that cannot be done at
+		 * interrupt time, so we must then queue the work.
+		 */
+		struct work_struct work_freeing;
+	};
+
+	/*
+	 * Per cgroup active and inactive list, similar to the
+	 * per zone LRU lists.
+	 */
+	struct mem_cgroup_lru_info info;
+	int last_scanned_node;
+#if MAX_NUMNODES > 1
+	nodemask_t	scan_nodes;
+	atomic_t	numainfo_events;
+	atomic_t	numainfo_updating;
+#endif
+	/*
+	 * Should the accounting and control be hierarchical, per subtree?
+	 */
+	bool use_hierarchy;
+
+	bool		oom_lock;
+	atomic_t	under_oom;
+
+	atomic_t	refcnt;
+
+	int	swappiness;
+	/* OOM-Killer disable */
+	int		oom_kill_disable;
+
+	/* set when res.limit == memsw.limit */
+	bool		memsw_is_minimum;
+
+	/* protect arrays of thresholds */
+	struct mutex thresholds_lock;
+
+	/* thresholds for memory usage. RCU-protected */
+	struct mem_cgroup_thresholds thresholds;
+
+	/* thresholds for mem+swap usage. RCU-protected */
+	struct mem_cgroup_thresholds memsw_thresholds;
+
+	/* For oom notifier event fd */
+	struct list_head oom_notify;
+
+	/*
+	 * Should we move charges of a task when a task is moved into this
+	 * mem_cgroup ? And what type of charges should we move ?
+	 */
+	unsigned long 	move_charge_at_immigrate;
+	/*
+	 * set > 0 if pages under this cgroup are moving to other cgroup.
+	 */
+	atomic_t	moving_account;
+	/* taken only while moving_account > 0 */
+	spinlock_t	move_lock;
+	/*
+	 * percpu counter.
+	 */
+	struct mem_cgroup_stat_cpu *stat;
+	/*
+	 * used when a cpu is offlined or other synchronizations
+	 * See mem_cgroup_read_stat().
+	 */
+	struct mem_cgroup_stat_cpu nocpu_base;
+	spinlock_t pcp_counter_lock;
+
+#ifdef CONFIG_INET
+	struct tcp_memcontrol tcp_mem;
+#endif
+};
+
+/* Stuffs for move charges at task migration. */
+/*
+ * Types of charges to be moved. "move_charge_at_immitgrate" is treated as a
+ * left-shifted bitmap of these types.
+ */
+enum move_type {
+	MOVE_CHARGE_TYPE_ANON,	/* private anonymous page and swap of it */
+	MOVE_CHARGE_TYPE_FILE,	/* file page(including tmpfs) and swap of it */
+	NR_MOVE_TYPE,
+};
+
+/* "mc" and its members are protected by cgroup_mutex */
+static struct move_charge_struct {
+	spinlock_t	  lock; /* for from, to */
+	struct mem_cgroup *from;
+	struct mem_cgroup *to;
+	unsigned long precharge;
+	unsigned long moved_charge;
+	unsigned long moved_swap;
+	struct task_struct *moving_task;	/* a task moving charges */
+	wait_queue_head_t waitq;		/* a waitq for other context */
+} mc = {
+	.lock = __SPIN_LOCK_UNLOCKED(mc.lock),
+	.waitq = __WAIT_QUEUE_HEAD_INITIALIZER(mc.waitq),
+};
+
+static bool move_anon(void)
+{
+	return test_bit(MOVE_CHARGE_TYPE_ANON,
+					&mc.to->move_charge_at_immigrate);
+}
+
+static bool move_file(void)
+{
+	return test_bit(MOVE_CHARGE_TYPE_FILE,
+					&mc.to->move_charge_at_immigrate);
+}
+
+/*
+ * Maximum loops in mem_cgroup_hierarchical_reclaim(), used for soft
+ * limit reclaim to prevent infinite loops, if they ever occur.
+ */
+#define	MEM_CGROUP_MAX_RECLAIM_LOOPS		(100)
+#define	MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS	(2)
+
+enum charge_type {
+	MEM_CGROUP_CHARGE_TYPE_CACHE = 0,
+	MEM_CGROUP_CHARGE_TYPE_MAPPED,
+	MEM_CGROUP_CHARGE_TYPE_SHMEM,	/* used by page migration of shmem */
+	MEM_CGROUP_CHARGE_TYPE_FORCE,	/* used by force_empty */
+	MEM_CGROUP_CHARGE_TYPE_SWAPOUT,	/* for accounting swapcache */
+	MEM_CGROUP_CHARGE_TYPE_DROP,	/* a page was unused swap cache */
+	NR_CHARGE_TYPE,
+};
+
+/* for encoding cft->private value on file */
+#define _MEM			(0)
+#define _MEMSWAP		(1)
+#define _OOM_TYPE		(2)
+#define MEMFILE_PRIVATE(x, val)	(((x) << 16) | (val))
+#define MEMFILE_TYPE(val)	(((val) >> 16) & 0xffff)
+#define MEMFILE_ATTR(val)	((val) & 0xffff)
+/* Used for OOM nofiier */
+#define OOM_CONTROL		(0)
+
+/*
+ * Reclaim flags for mem_cgroup_hierarchical_reclaim
+ */
+#define MEM_CGROUP_RECLAIM_NOSWAP_BIT	0x0
+#define MEM_CGROUP_RECLAIM_NOSWAP	(1 << MEM_CGROUP_RECLAIM_NOSWAP_BIT)
+#define MEM_CGROUP_RECLAIM_SHRINK_BIT	0x1
+#define MEM_CGROUP_RECLAIM_SHRINK	(1 << MEM_CGROUP_RECLAIM_SHRINK_BIT)
+
+static void mem_cgroup_get(struct mem_cgroup *memcg);
+static void mem_cgroup_put(struct mem_cgroup *memcg);
+
+/* Writing them here to avoid exposing memcg's inner layout */
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
+#include <net/sock.h>
+#include <net/ip.h>
+
+static bool mem_cgroup_is_root(struct mem_cgroup *memcg);
+void sock_update_memcg(struct sock *sk)
+{
+	if (mem_cgroup_sockets_enabled) {
+		struct mem_cgroup *memcg;
+
+		BUG_ON(!sk->sk_prot->proto_cgroup);
+
+		/* Socket cloning can throw us here with sk_cgrp already
+		 * filled. It won't however, necessarily happen from
+		 * process context. So the test for root memcg given
+		 * the current task's memcg won't help us in this case.
+		 *
+		 * Respecting the original socket's memcg is a better
+		 * decision in this case.
+		 */
+		if (sk->sk_cgrp) {
+			BUG_ON(mem_cgroup_is_root(sk->sk_cgrp->memcg));
+			mem_cgroup_get(sk->sk_cgrp->memcg);
+			return;
+		}
+
+		rcu_read_lock();
+		memcg = mem_cgroup_from_task(current);
+		if (!mem_cgroup_is_root(memcg)) {
+			mem_cgroup_get(memcg);
+			sk->sk_cgrp = sk->sk_prot->proto_cgroup(memcg);
+		}
+		rcu_read_unlock();
+	}
+}
+EXPORT_SYMBOL(sock_update_memcg);
+
+void sock_release_memcg(struct sock *sk)
+{
+	if (mem_cgroup_sockets_enabled && sk->sk_cgrp) {
+		struct mem_cgroup *memcg;
+		WARN_ON(!sk->sk_cgrp->memcg);
+		memcg = sk->sk_cgrp->memcg;
+		mem_cgroup_put(memcg);
+	}
+}
+
+#ifdef CONFIG_INET
+struct cg_proto *tcp_proto_cgroup(struct mem_cgroup *memcg)
+{
+	if (!memcg || mem_cgroup_is_root(memcg))
+		return NULL;
+
+	return &memcg->tcp_mem.cg_proto;
+}
+EXPORT_SYMBOL(tcp_proto_cgroup);
+#endif /* CONFIG_INET */
+#endif /* CONFIG_CGROUP_MEM_RES_CTLR_KMEM */
+
+static void drain_all_stock_async(struct mem_cgroup *memcg);
+
+static struct mem_cgroup_per_zone *
+mem_cgroup_zoneinfo(struct mem_cgroup *memcg, int nid, int zid)
+{
+	return &memcg->info.nodeinfo[nid]->zoneinfo[zid];
+}
+
+struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *memcg)
+{
+	return &memcg->css;
+}
+
+static struct mem_cgroup_per_zone *
+page_cgroup_zoneinfo(struct mem_cgroup *memcg, struct page *page)
+{
+	int nid = page_to_nid(page);
+	int zid = page_zonenum(page);
+
+	return mem_cgroup_zoneinfo(memcg, nid, zid);
+}
+
+static struct mem_cgroup_tree_per_zone *
+soft_limit_tree_node_zone(int nid, int zid)
+{
+	return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid];
+}
+
+static struct mem_cgroup_tree_per_zone *
+soft_limit_tree_from_page(struct page *page)
+{
+	int nid = page_to_nid(page);
+	int zid = page_zonenum(page);
+
+	return &soft_limit_tree.rb_tree_per_node[nid]->rb_tree_per_zone[zid];
+}
+
+static void
+__mem_cgroup_insert_exceeded(struct mem_cgroup *memcg,
+				struct mem_cgroup_per_zone *mz,
+				struct mem_cgroup_tree_per_zone *mctz,
+				unsigned long long new_usage_in_excess)
+{
+	struct rb_node **p = &mctz->rb_root.rb_node;
+	struct rb_node *parent = NULL;
+	struct mem_cgroup_per_zone *mz_node;
+
+	if (mz->on_tree)
+		return;
+
+	mz->usage_in_excess = new_usage_in_excess;
+	if (!mz->usage_in_excess)
+		return;
+	while (*p) {
+		parent = *p;
+		mz_node = rb_entry(parent, struct mem_cgroup_per_zone,
+					tree_node);
+		if (mz->usage_in_excess < mz_node->usage_in_excess)
+			p = &(*p)->rb_left;
+		/*
+		 * We can't avoid mem cgroups that are over their soft
+		 * limit by the same amount
+		 */
+		else if (mz->usage_in_excess >= mz_node->usage_in_excess)
+			p = &(*p)->rb_right;
+	}
+	rb_link_node(&mz->tree_node, parent, p);
+	rb_insert_color(&mz->tree_node, &mctz->rb_root);
+	mz->on_tree = true;
+}
+
+static void
+__mem_cgroup_remove_exceeded(struct mem_cgroup *memcg,
+				struct mem_cgroup_per_zone *mz,
+				struct mem_cgroup_tree_per_zone *mctz)
+{
+	if (!mz->on_tree)
+		return;
+	rb_erase(&mz->tree_node, &mctz->rb_root);
+	mz->on_tree = false;
+}
+
+static void
+mem_cgroup_remove_exceeded(struct mem_cgroup *memcg,
+				struct mem_cgroup_per_zone *mz,
+				struct mem_cgroup_tree_per_zone *mctz)
+{
+	spin_lock(&mctz->lock);
+	__mem_cgroup_remove_exceeded(memcg, mz, mctz);
+	spin_unlock(&mctz->lock);
+}
+
+
+static void mem_cgroup_update_tree(struct mem_cgroup *memcg, struct page *page)
+{
+	unsigned long long excess;
+	struct mem_cgroup_per_zone *mz;
+	struct mem_cgroup_tree_per_zone *mctz;
+	int nid = page_to_nid(page);
+	int zid = page_zonenum(page);
+	mctz = soft_limit_tree_from_page(page);
+
+	/*
+	 * Necessary to update all ancestors when hierarchy is used.
+	 * because their event counter is not touched.
+	 */
+	for (; memcg; memcg = parent_mem_cgroup(memcg)) {
+		mz = mem_cgroup_zoneinfo(memcg, nid, zid);
+		excess = res_counter_soft_limit_excess(&memcg->res);
+		/*
+		 * We have to update the tree if mz is on RB-tree or
+		 * mem is over its softlimit.
+		 */
+		if (excess || mz->on_tree) {
+			spin_lock(&mctz->lock);
+			/* if on-tree, remove it */
+			if (mz->on_tree)
+				__mem_cgroup_remove_exceeded(memcg, mz, mctz);
+			/*
+			 * Insert again. mz->usage_in_excess will be updated.
+			 * If excess is 0, no tree ops.
+			 */
+			__mem_cgroup_insert_exceeded(memcg, mz, mctz, excess);
+			spin_unlock(&mctz->lock);
+		}
+	}
+}
+
+static void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg)
+{
+	int node, zone;
+	struct mem_cgroup_per_zone *mz;
+	struct mem_cgroup_tree_per_zone *mctz;
+
+	for_each_node(node) {
+		for (zone = 0; zone < MAX_NR_ZONES; zone++) {
+			mz = mem_cgroup_zoneinfo(memcg, node, zone);
+			mctz = soft_limit_tree_node_zone(node, zone);
+			mem_cgroup_remove_exceeded(memcg, mz, mctz);
+		}
+	}
+}
+
+static struct mem_cgroup_per_zone *
+__mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
+{
+	struct rb_node *rightmost = NULL;
+	struct mem_cgroup_per_zone *mz;
+
+retry:
+	mz = NULL;
+	rightmost = rb_last(&mctz->rb_root);
+	if (!rightmost)
+		goto done;		/* Nothing to reclaim from */
+
+	mz = rb_entry(rightmost, struct mem_cgroup_per_zone, tree_node);
+	/*
+	 * Remove the node now but someone else can add it back,
+	 * we will to add it back at the end of reclaim to its correct
+	 * position in the tree.
+	 */
+	__mem_cgroup_remove_exceeded(mz->memcg, mz, mctz);
+	if (!res_counter_soft_limit_excess(&mz->memcg->res) ||
+		!css_tryget(&mz->memcg->css))
+		goto retry;
+done:
+	return mz;
+}
+
+static struct mem_cgroup_per_zone *
+mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_zone *mctz)
+{
+	struct mem_cgroup_per_zone *mz;
+
+	spin_lock(&mctz->lock);
+	mz = __mem_cgroup_largest_soft_limit_node(mctz);
+	spin_unlock(&mctz->lock);
+	return mz;
+}
+
+/*
+ * Implementation Note: reading percpu statistics for memcg.
+ *
+ * Both of vmstat[] and percpu_counter has threshold and do periodic
+ * synchronization to implement "quick" read. There are trade-off between
+ * reading cost and precision of value. Then, we may have a chance to implement
+ * a periodic synchronizion of counter in memcg's counter.
+ *
+ * But this _read() function is used for user interface now. The user accounts
+ * memory usage by memory cgroup and he _always_ requires exact value because
+ * he accounts memory. Even if we provide quick-and-fuzzy read, we always
+ * have to visit all online cpus and make sum. So, for now, unnecessary
+ * synchronization is not implemented. (just implemented for cpu hotplug)
+ *
+ * If there are kernel internal actions which can make use of some not-exact
+ * value, and reading all cpu value can be performance bottleneck in some
+ * common workload, threashold and synchonization as vmstat[] should be
+ * implemented.
+ */
+static long mem_cgroup_read_stat(struct mem_cgroup *memcg,
+				 enum mem_cgroup_stat_index idx)
+{
+	long val = 0;
+	int cpu;
+
+	get_online_cpus();
+	for_each_online_cpu(cpu)
+		val += per_cpu(memcg->stat->count[idx], cpu);
+#ifdef CONFIG_HOTPLUG_CPU
+	spin_lock(&memcg->pcp_counter_lock);
+	val += memcg->nocpu_base.count[idx];
+	spin_unlock(&memcg->pcp_counter_lock);
+#endif
+	put_online_cpus();
+	return val;
+}
+
+static void mem_cgroup_swap_statistics(struct mem_cgroup *memcg,
+					 bool charge)
+{
+	int val = (charge) ? 1 : -1;
+	this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_SWAPOUT], val);
+}
+
+static unsigned long mem_cgroup_read_events(struct mem_cgroup *memcg,
+					    enum mem_cgroup_events_index idx)
+{
+	unsigned long val = 0;
+	int cpu;
+
+	for_each_online_cpu(cpu)
+		val += per_cpu(memcg->stat->events[idx], cpu);
+#ifdef CONFIG_HOTPLUG_CPU
+	spin_lock(&memcg->pcp_counter_lock);
+	val += memcg->nocpu_base.events[idx];
+	spin_unlock(&memcg->pcp_counter_lock);
+#endif
+	return val;
+}
+
+static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg,
+					 bool anon, int nr_pages)
+{
+	preempt_disable();
+
+	/*
+	 * Here, RSS means 'mapped anon' and anon's SwapCache. Shmem/tmpfs is
+	 * counted as CACHE even if it's on ANON LRU.
+	 */
+	if (anon)
+		__this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_RSS],
+				nr_pages);
+	else
+		__this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_CACHE],
+				nr_pages);
+
+	/* pagein of a big page is an event. So, ignore page size */
+	if (nr_pages > 0)
+		__this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGPGIN]);
+	else {
+		__this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGPGOUT]);
+		nr_pages = -nr_pages; /* for event */
+	}
+
+	__this_cpu_add(memcg->stat->events[MEM_CGROUP_EVENTS_COUNT], nr_pages);
+
+	preempt_enable();
+}
+
+unsigned long
+mem_cgroup_zone_nr_lru_pages(struct mem_cgroup *memcg, int nid, int zid,
+			unsigned int lru_mask)
+{
+	struct mem_cgroup_per_zone *mz;
+	enum lru_list lru;
+	unsigned long ret = 0;
+
+	mz = mem_cgroup_zoneinfo(memcg, nid, zid);
+
+	for_each_lru(lru) {
+		if (BIT(lru) & lru_mask)
+			ret += mz->lru_size[lru];
+	}
+	return ret;
+}
+
+static unsigned long
+mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg,
+			int nid, unsigned int lru_mask)
+{
+	u64 total = 0;
+	int zid;
+
+	for (zid = 0; zid < MAX_NR_ZONES; zid++)
+		total += mem_cgroup_zone_nr_lru_pages(memcg,
+						nid, zid, lru_mask);
+
+	return total;
+}
+
+static unsigned long mem_cgroup_nr_lru_pages(struct mem_cgroup *memcg,
+			unsigned int lru_mask)
+{
+	int nid;
+	u64 total = 0;
+
+	for_each_node_state(nid, N_HIGH_MEMORY)
+		total += mem_cgroup_node_nr_lru_pages(memcg, nid, lru_mask);
+	return total;
+}
+
+static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
+				       enum mem_cgroup_events_target target)
+{
+	unsigned long val, next;
+
+	val = __this_cpu_read(memcg->stat->events[MEM_CGROUP_EVENTS_COUNT]);
+	next = __this_cpu_read(memcg->stat->targets[target]);
+	/* from time_after() in jiffies.h */
+	if ((long)next - (long)val < 0) {
+		switch (target) {
+		case MEM_CGROUP_TARGET_THRESH:
+			next = val + THRESHOLDS_EVENTS_TARGET;
+			break;
+		case MEM_CGROUP_TARGET_SOFTLIMIT:
+			next = val + SOFTLIMIT_EVENTS_TARGET;
+			break;
+		case MEM_CGROUP_TARGET_NUMAINFO:
+			next = val + NUMAINFO_EVENTS_TARGET;
+			break;
+		default:
+			break;
+		}
+		__this_cpu_write(memcg->stat->targets[target], next);
+		return true;
+	}
+	return false;
+}
+
+/*
+ * Check events in order.
+ *
+ */
+static void memcg_check_events(struct mem_cgroup *memcg, struct page *page)
+{
+	preempt_disable();
+	/* threshold event is triggered in finer grain than soft limit */
+	if (unlikely(mem_cgroup_event_ratelimit(memcg,
+						MEM_CGROUP_TARGET_THRESH))) {
+		bool do_softlimit;
+		bool do_numainfo __maybe_unused;
+
+		do_softlimit = mem_cgroup_event_ratelimit(memcg,
+						MEM_CGROUP_TARGET_SOFTLIMIT);
+#if MAX_NUMNODES > 1
+		do_numainfo = mem_cgroup_event_ratelimit(memcg,
+						MEM_CGROUP_TARGET_NUMAINFO);
+#endif
+		preempt_enable();
+
+		mem_cgroup_threshold(memcg);
+		if (unlikely(do_softlimit))
+			mem_cgroup_update_tree(memcg, page);
+#if MAX_NUMNODES > 1
+		if (unlikely(do_numainfo))
+			atomic_inc(&memcg->numainfo_events);
+#endif
+	} else
+		preempt_enable();
+}
+
+struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
+{
+	return container_of(cgroup_subsys_state(cont,
+				mem_cgroup_subsys_id), struct mem_cgroup,
+				css);
+}
+
+struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
+{
+	/*
+	 * mm_update_next_owner() may clear mm->owner to NULL
+	 * if it races with swapoff, page migration, etc.
+	 * So this can be called with p == NULL.
+	 */
+	if (unlikely(!p))
+		return NULL;
+
+	return container_of(task_subsys_state(p, mem_cgroup_subsys_id),
+				struct mem_cgroup, css);
+}
+
+struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
+{
+	struct mem_cgroup *memcg = NULL;
+
+	if (!mm)
+		return NULL;
+	/*
+	 * Because we have no locks, mm->owner's may be being moved to other
+	 * cgroup. We use css_tryget() here even if this looks
+	 * pessimistic (rather than adding locks here).
+	 */
+	rcu_read_lock();
+	do {
+		memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
+		if (unlikely(!memcg))
+			break;
+	} while (!css_tryget(&memcg->css));
+	rcu_read_unlock();
+	return memcg;
+}
+
+/**
+ * mem_cgroup_iter - iterate over memory cgroup hierarchy
+ * @root: hierarchy root
+ * @prev: previously returned memcg, NULL on first invocation
+ * @reclaim: cookie for shared reclaim walks, NULL for full walks
+ *
+ * Returns references to children of the hierarchy below @root, or
+ * @root itself, or %NULL after a full round-trip.
+ *
+ * Caller must pass the return value in @prev on subsequent
+ * invocations for reference counting, or use mem_cgroup_iter_break()
+ * to cancel a hierarchy walk before the round-trip is complete.
+ *
+ * Reclaimers can specify a zone and a priority level in @reclaim to
+ * divide up the memcgs in the hierarchy among all concurrent
+ * reclaimers operating on the same zone and priority.
+ */
+struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
+				   struct mem_cgroup *prev,
+				   struct mem_cgroup_reclaim_cookie *reclaim)
+{
+	struct mem_cgroup *memcg = NULL;
+	int id = 0;
+
+	if (mem_cgroup_disabled())
+		return NULL;
+
+	if (!root)
+		root = root_mem_cgroup;
+
+	if (prev && !reclaim)
+		id = css_id(&prev->css);
+
+	if (prev && prev != root)
+		css_put(&prev->css);
+
+	if (!root->use_hierarchy && root != root_mem_cgroup) {
+		if (prev)
+			return NULL;
+		return root;
+	}
+
+	while (!memcg) {
+		struct mem_cgroup_reclaim_iter *uninitialized_var(iter);
+		struct cgroup_subsys_state *css;
+
+		if (reclaim) {
+			int nid = zone_to_nid(reclaim->zone);
+			int zid = zone_idx(reclaim->zone);
+			struct mem_cgroup_per_zone *mz;
+
+			mz = mem_cgroup_zoneinfo(root, nid, zid);
+			iter = &mz->reclaim_iter[reclaim->priority];
+			if (prev && reclaim->generation != iter->generation)
+				return NULL;
+			id = iter->position;
+		}
+
+		rcu_read_lock();
+		css = css_get_next(&mem_cgroup_subsys, id + 1, &root->css, &id);
+		if (css) {
+			if (css == &root->css || css_tryget(css))
+				memcg = container_of(css,
+						     struct mem_cgroup, css);
+		} else
+			id = 0;
+		rcu_read_unlock();
+
+		if (reclaim) {
+			iter->position = id;
+			if (!css)
+				iter->generation++;
+			else if (!prev && memcg)
+				reclaim->generation = iter->generation;
+		}
+
+		if (prev && !css)
+			return NULL;
+	}
+	return memcg;
+}
+
+/**
+ * mem_cgroup_iter_break - abort a hierarchy walk prematurely
+ * @root: hierarchy root
+ * @prev: last visited hierarchy member as returned by mem_cgroup_iter()
+ */
+void mem_cgroup_iter_break(struct mem_cgroup *root,
+			   struct mem_cgroup *prev)
+{
+	if (!root)
+		root = root_mem_cgroup;
+	if (prev && prev != root)
+		css_put(&prev->css);
+}
+
+/*
+ * Iteration constructs for visiting all cgroups (under a tree).  If
+ * loops are exited prematurely (break), mem_cgroup_iter_break() must
+ * be used for reference counting.
+ */
+#define for_each_mem_cgroup_tree(iter, root)		\
+	for (iter = mem_cgroup_iter(root, NULL, NULL);	\
+	     iter != NULL;				\
+	     iter = mem_cgroup_iter(root, iter, NULL))
+
+#define for_each_mem_cgroup(iter)			\
+	for (iter = mem_cgroup_iter(NULL, NULL, NULL);	\
+	     iter != NULL;				\
+	     iter = mem_cgroup_iter(NULL, iter, NULL))
+
+static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg)
+{
+	return (memcg == root_mem_cgroup);
+}
+
+void mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx)
+{
+	struct mem_cgroup *memcg;
+
+	if (!mm)
+		return;
+
+	rcu_read_lock();
+	memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
+	if (unlikely(!memcg))
+		goto out;
+
+	switch (idx) {
+	case PGFAULT:
+		this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGFAULT]);
+		break;
+	case PGMAJFAULT:
+		this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGMAJFAULT]);
+		break;
+	default:
+		BUG();
+	}
+out:
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL(mem_cgroup_count_vm_event);
+
+/**
+ * mem_cgroup_zone_lruvec - get the lru list vector for a zone and memcg
+ * @zone: zone of the wanted lruvec
+ * @mem: memcg of the wanted lruvec
+ *
+ * Returns the lru list vector holding pages for the given @zone and
+ * @mem.  This can be the global zone lruvec, if the memory controller
+ * is disabled.
+ */
+struct lruvec *mem_cgroup_zone_lruvec(struct zone *zone,
+				      struct mem_cgroup *memcg)
+{
+	struct mem_cgroup_per_zone *mz;
+
+	if (mem_cgroup_disabled())
+		return &zone->lruvec;
+
+	mz = mem_cgroup_zoneinfo(memcg, zone_to_nid(zone), zone_idx(zone));
+	return &mz->lruvec;
+}
+
+/*
+ * Following LRU functions are allowed to be used without PCG_LOCK.
+ * Operations are called by routine of global LRU independently from memcg.
+ * What we have to take care of here is validness of pc->mem_cgroup.
+ *
+ * Changes to pc->mem_cgroup happens when
+ * 1. charge
+ * 2. moving account
+ * In typical case, "charge" is done before add-to-lru. Exception is SwapCache.
+ * It is added to LRU before charge.
+ * If PCG_USED bit is not set, page_cgroup is not added to this private LRU.
+ * When moving account, the page is not on LRU. It's isolated.
+ */
+
+/**
+ * mem_cgroup_lru_add_list - account for adding an lru page and return lruvec
+ * @zone: zone of the page
+ * @page: the page
+ * @lru: current lru
+ *
+ * This function accounts for @page being added to @lru, and returns
+ * the lruvec for the given @zone and the memcg @page is charged to.
+ *
+ * The callsite is then responsible for physically linking the page to
+ * the returned lruvec->lists[@lru].
+ */
+struct lruvec *mem_cgroup_lru_add_list(struct zone *zone, struct page *page,
+				       enum lru_list lru)
+{
+	struct mem_cgroup_per_zone *mz;
+	struct mem_cgroup *memcg;
+	struct page_cgroup *pc;
+
+	if (mem_cgroup_disabled())
+		return &zone->lruvec;
+
+	pc = lookup_page_cgroup(page);
+	memcg = pc->mem_cgroup;
+
+	/*
+	 * Surreptitiously switch any uncharged page to root:
+	 * an uncharged page off lru does nothing to secure
+	 * its former mem_cgroup from sudden removal.
+	 *
+	 * Our caller holds lru_lock, and PageCgroupUsed is updated
+	 * under page_cgroup lock: between them, they make all uses
+	 * of pc->mem_cgroup safe.
+	 */
+	if (!PageCgroupUsed(pc) && memcg != root_mem_cgroup)
+		pc->mem_cgroup = memcg = root_mem_cgroup;
+
+	mz = page_cgroup_zoneinfo(memcg, page);
+	/* compound_order() is stabilized through lru_lock */
+	mz->lru_size[lru] += 1 << compound_order(page);
+	return &mz->lruvec;
+}
+
+/**
+ * mem_cgroup_lru_del_list - account for removing an lru page
+ * @page: the page
+ * @lru: target lru
+ *
+ * This function accounts for @page being removed from @lru.
+ *
+ * The callsite is then responsible for physically unlinking
+ * @page->lru.
+ */
+void mem_cgroup_lru_del_list(struct page *page, enum lru_list lru)
+{
+	struct mem_cgroup_per_zone *mz;
+	struct mem_cgroup *memcg;
+	struct page_cgroup *pc;
+
+	if (mem_cgroup_disabled())
+		return;
+
+	pc = lookup_page_cgroup(page);
+	memcg = pc->mem_cgroup;
+	VM_BUG_ON(!memcg);
+	mz = page_cgroup_zoneinfo(memcg, page);
+	/* huge page split is done under lru_lock. so, we have no races. */
+	VM_BUG_ON(mz->lru_size[lru] < (1 << compound_order(page)));
+	mz->lru_size[lru] -= 1 << compound_order(page);
+}
+
+void mem_cgroup_lru_del(struct page *page)
+{
+	mem_cgroup_lru_del_list(page, page_lru(page));
+}
+
+/**
+ * mem_cgroup_lru_move_lists - account for moving a page between lrus
+ * @zone: zone of the page
+ * @page: the page
+ * @from: current lru
+ * @to: target lru
+ *
+ * This function accounts for @page being moved between the lrus @from
+ * and @to, and returns the lruvec for the given @zone and the memcg
+ * @page is charged to.
+ *
+ * The callsite is then responsible for physically relinking
+ * @page->lru to the returned lruvec->lists[@to].
+ */
+struct lruvec *mem_cgroup_lru_move_lists(struct zone *zone,
+					 struct page *page,
+					 enum lru_list from,
+					 enum lru_list to)
+{
+	/* XXX: Optimize this, especially for @from == @to */
+	mem_cgroup_lru_del_list(page, from);
+	return mem_cgroup_lru_add_list(zone, page, to);
+}
+
+/*
+ * Checks whether given mem is same or in the root_mem_cgroup's
+ * hierarchy subtree
+ */
+static bool mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg,
+		struct mem_cgroup *memcg)
+{
+	if (root_memcg != memcg) {
+		return (root_memcg->use_hierarchy &&
+			css_is_ancestor(&memcg->css, &root_memcg->css));
+	}
+
+	return true;
+}
+
+int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *memcg)
+{
+	int ret;
+	struct mem_cgroup *curr = NULL;
+	struct task_struct *p;
+
+	p = find_lock_task_mm(task);
+	if (p) {
+		curr = try_get_mem_cgroup_from_mm(p->mm);
+		task_unlock(p);
+	} else {
+		/*
+		 * All threads may have already detached their mm's, but the oom
+		 * killer still needs to detect if they have already been oom
+		 * killed to prevent needlessly killing additional tasks.
+		 */
+		task_lock(task);
+		curr = mem_cgroup_from_task(task);
+		if (curr)
+			css_get(&curr->css);
+		task_unlock(task);
+	}
+	if (!curr)
+		return 0;
+	/*
+	 * We should check use_hierarchy of "memcg" not "curr". Because checking
+	 * use_hierarchy of "curr" here make this function true if hierarchy is
+	 * enabled in "curr" and "curr" is a child of "memcg" in *cgroup*
+	 * hierarchy(even if use_hierarchy is disabled in "memcg").
+	 */
+	ret = mem_cgroup_same_or_subtree(memcg, curr);
+	css_put(&curr->css);
+	return ret;
+}
+
+int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg, struct zone *zone)
+{
+	unsigned long inactive_ratio;
+	int nid = zone_to_nid(zone);
+	int zid = zone_idx(zone);
+	unsigned long inactive;
+	unsigned long active;
+	unsigned long gb;
+
+	inactive = mem_cgroup_zone_nr_lru_pages(memcg, nid, zid,
+						BIT(LRU_INACTIVE_ANON));
+	active = mem_cgroup_zone_nr_lru_pages(memcg, nid, zid,
+					      BIT(LRU_ACTIVE_ANON));
+
+	gb = (inactive + active) >> (30 - PAGE_SHIFT);
+	if (gb)
+		inactive_ratio = int_sqrt(10 * gb);
+	else
+		inactive_ratio = 1;
+
+	return inactive * inactive_ratio < active;
+}
+
+int mem_cgroup_inactive_file_is_low(struct mem_cgroup *memcg, struct zone *zone)
+{
+	unsigned long active;
+	unsigned long inactive;
+	int zid = zone_idx(zone);
+	int nid = zone_to_nid(zone);
+
+	inactive = mem_cgroup_zone_nr_lru_pages(memcg, nid, zid,
+						BIT(LRU_INACTIVE_FILE));
+	active = mem_cgroup_zone_nr_lru_pages(memcg, nid, zid,
+					      BIT(LRU_ACTIVE_FILE));
+
+	return (active > inactive);
+}
+
+struct zone_reclaim_stat *mem_cgroup_get_reclaim_stat(struct mem_cgroup *memcg,
+						      struct zone *zone)
+{
+	int nid = zone_to_nid(zone);
+	int zid = zone_idx(zone);
+	struct mem_cgroup_per_zone *mz = mem_cgroup_zoneinfo(memcg, nid, zid);
+
+	return &mz->reclaim_stat;
+}
+
+struct zone_reclaim_stat *
+mem_cgroup_get_reclaim_stat_from_page(struct page *page)
+{
+	struct page_cgroup *pc;
+	struct mem_cgroup_per_zone *mz;
+
+	if (mem_cgroup_disabled())
+		return NULL;
+
+	pc = lookup_page_cgroup(page);
+	if (!PageCgroupUsed(pc))
+		return NULL;
+	/* Ensure pc->mem_cgroup is visible after reading PCG_USED. */
+	smp_rmb();
+	mz = page_cgroup_zoneinfo(pc->mem_cgroup, page);
+	return &mz->reclaim_stat;
+}
+
+#define mem_cgroup_from_res_counter(counter, member)	\
+	container_of(counter, struct mem_cgroup, member)
+
+/**
+ * mem_cgroup_margin - calculate chargeable space of a memory cgroup
+ * @mem: the memory cgroup
+ *
+ * Returns the maximum amount of memory @mem can be charged with, in
+ * pages.
+ */
+static unsigned long mem_cgroup_margin(struct mem_cgroup *memcg)
+{
+	unsigned long long margin;
+
+	margin = res_counter_margin(&memcg->res);
+	if (do_swap_account)
+		margin = min(margin, res_counter_margin(&memcg->memsw));
+	return margin >> PAGE_SHIFT;
+}
+
+int mem_cgroup_swappiness(struct mem_cgroup *memcg)
+{
+	struct cgroup *cgrp = memcg->css.cgroup;
+
+	/* root ? */
+	if (cgrp->parent == NULL)
+		return vm_swappiness;
+
+	return memcg->swappiness;
+}
+
+/*
+ * memcg->moving_account is used for checking possibility that some thread is
+ * calling move_account(). When a thread on CPU-A starts moving pages under
+ * a memcg, other threads should check memcg->moving_account under
+ * rcu_read_lock(), like this:
+ *
+ *         CPU-A                                    CPU-B
+ *                                              rcu_read_lock()
+ *         memcg->moving_account+1              if (memcg->mocing_account)
+ *                                                   take heavy locks.
+ *         synchronize_rcu()                    update something.
+ *                                              rcu_read_unlock()
+ *         start move here.
+ */
+
+/* for quick checking without looking up memcg */
+atomic_t memcg_moving __read_mostly;
+
+static void mem_cgroup_start_move(struct mem_cgroup *memcg)
+{
+	atomic_inc(&memcg_moving);
+	atomic_inc(&memcg->moving_account);
+	synchronize_rcu();
+}
+
+static void mem_cgroup_end_move(struct mem_cgroup *memcg)
+{
+	/*
+	 * Now, mem_cgroup_clear_mc() may call this function with NULL.
+	 * We check NULL in callee rather than caller.
+	 */
+	if (memcg) {
+		atomic_dec(&memcg_moving);
+		atomic_dec(&memcg->moving_account);
+	}
+}
+
+/*
+ * 2 routines for checking "mem" is under move_account() or not.
+ *
+ * mem_cgroup_stolen() -  checking whether a cgroup is mc.from or not. This
+ *			  is used for avoiding races in accounting.  If true,
+ *			  pc->mem_cgroup may be overwritten.
+ *
+ * mem_cgroup_under_move() - checking a cgroup is mc.from or mc.to or
+ *			  under hierarchy of moving cgroups. This is for
+ *			  waiting at hith-memory prressure caused by "move".
+ */
+
+static bool mem_cgroup_stolen(struct mem_cgroup *memcg)
+{
+	VM_BUG_ON(!rcu_read_lock_held());
+	return atomic_read(&memcg->moving_account) > 0;
+}
+
+static bool mem_cgroup_under_move(struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *from;
+	struct mem_cgroup *to;
+	bool ret = false;
+	/*
+	 * Unlike task_move routines, we access mc.to, mc.from not under
+	 * mutual exclusion by cgroup_mutex. Here, we take spinlock instead.
+	 */
+	spin_lock(&mc.lock);
+	from = mc.from;
+	to = mc.to;
+	if (!from)
+		goto unlock;
+
+	ret = mem_cgroup_same_or_subtree(memcg, from)
+		|| mem_cgroup_same_or_subtree(memcg, to);
+unlock:
+	spin_unlock(&mc.lock);
+	return ret;
+}
+
+static bool mem_cgroup_wait_acct_move(struct mem_cgroup *memcg)
+{
+	if (mc.moving_task && current != mc.moving_task) {
+		if (mem_cgroup_under_move(memcg)) {
+			DEFINE_WAIT(wait);
+			prepare_to_wait(&mc.waitq, &wait, TASK_INTERRUPTIBLE);
+			/* moving charge context might have finished. */
+			if (mc.moving_task)
+				schedule();
+			finish_wait(&mc.waitq, &wait);
+			return true;
+		}
+	}
+	return false;
+}
+
+/*
+ * Take this lock when
+ * - a code tries to modify page's memcg while it's USED.
+ * - a code tries to modify page state accounting in a memcg.
+ * see mem_cgroup_stolen(), too.
+ */
+static void move_lock_mem_cgroup(struct mem_cgroup *memcg,
+				  unsigned long *flags)
+{
+	spin_lock_irqsave(&memcg->move_lock, *flags);
+}
+
+static void move_unlock_mem_cgroup(struct mem_cgroup *memcg,
+				unsigned long *flags)
+{
+	spin_unlock_irqrestore(&memcg->move_lock, *flags);
+}
+
+/**
+ * mem_cgroup_print_oom_info: Called from OOM with tasklist_lock held in read mode.
+ * @memcg: The memory cgroup that went over limit
+ * @p: Task that is going to be killed
+ *
+ * NOTE: @memcg and @p's mem_cgroup can be different when hierarchy is
+ * enabled
+ */
+void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
+{
+	struct cgroup *task_cgrp;
+	struct cgroup *mem_cgrp;
+	/*
+	 * Need a buffer in BSS, can't rely on allocations. The code relies
+	 * on the assumption that OOM is serialized for memory controller.
+	 * If this assumption is broken, revisit this code.
+	 */
+	static char memcg_name[PATH_MAX];
+	int ret;
+
+	if (!memcg || !p)
+		return;
+
+	rcu_read_lock();
+
+	mem_cgrp = memcg->css.cgroup;
+	task_cgrp = task_cgroup(p, mem_cgroup_subsys_id);
+
+	ret = cgroup_path(task_cgrp, memcg_name, PATH_MAX);
+	if (ret < 0) {
+		/*
+		 * Unfortunately, we are unable to convert to a useful name
+		 * But we'll still print out the usage information
+		 */
+		rcu_read_unlock();
+		goto done;
+	}
+	rcu_read_unlock();
+
+	printk(KERN_INFO "Task in %s killed", memcg_name);
+
+	rcu_read_lock();
+	ret = cgroup_path(mem_cgrp, memcg_name, PATH_MAX);
+	if (ret < 0) {
+		rcu_read_unlock();
+		goto done;
+	}
+	rcu_read_unlock();
+
+	/*
+	 * Continues from above, so we don't need an KERN_ level
+	 */
+	printk(KERN_CONT " as a result of limit of %s\n", memcg_name);
+done:
+
+	printk(KERN_INFO "memory: usage %llukB, limit %llukB, failcnt %llu\n",
+		res_counter_read_u64(&memcg->res, RES_USAGE) >> 10,
+		res_counter_read_u64(&memcg->res, RES_LIMIT) >> 10,
+		res_counter_read_u64(&memcg->res, RES_FAILCNT));
+	printk(KERN_INFO "memory+swap: usage %llukB, limit %llukB, "
+		"failcnt %llu\n",
+		res_counter_read_u64(&memcg->memsw, RES_USAGE) >> 10,
+		res_counter_read_u64(&memcg->memsw, RES_LIMIT) >> 10,
+		res_counter_read_u64(&memcg->memsw, RES_FAILCNT));
+}
+
+/*
+ * This function returns the number of memcg under hierarchy tree. Returns
+ * 1(self count) if no children.
+ */
+static int mem_cgroup_count_children(struct mem_cgroup *memcg)
+{
+	int num = 0;
+	struct mem_cgroup *iter;
+
+	for_each_mem_cgroup_tree(iter, memcg)
+		num++;
+	return num;
+}
+
+/*
+ * Return the memory (and swap, if configured) limit for a memcg.
+ */
+u64 mem_cgroup_get_limit(struct mem_cgroup *memcg)
+{
+	u64 limit;
+
+	limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
+
+	/*
+	 * Do not consider swap space if we cannot swap due to swappiness
+	 */
+	if (mem_cgroup_swappiness(memcg)) {
+		u64 memsw;
+
+		limit += total_swap_pages << PAGE_SHIFT;
+		memsw = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
+
+		/*
+		 * If memsw is finite and limits the amount of swap space
+		 * available to this memcg, return that limit.
+		 */
+		limit = min(limit, memsw);
+	}
+
+	return limit;
+}
+
+static unsigned long mem_cgroup_reclaim(struct mem_cgroup *memcg,
+					gfp_t gfp_mask,
+					unsigned long flags)
+{
+	unsigned long total = 0;
+	bool noswap = false;
+	int loop;
+
+	if (flags & MEM_CGROUP_RECLAIM_NOSWAP)
+		noswap = true;
+	if (!(flags & MEM_CGROUP_RECLAIM_SHRINK) && memcg->memsw_is_minimum)
+		noswap = true;
+
+	for (loop = 0; loop < MEM_CGROUP_MAX_RECLAIM_LOOPS; loop++) {
+		if (loop)
+			drain_all_stock_async(memcg);
+		total += try_to_free_mem_cgroup_pages(memcg, gfp_mask, noswap);
+		/*
+		 * Allow limit shrinkers, which are triggered directly
+		 * by userspace, to catch signals and stop reclaim
+		 * after minimal progress, regardless of the margin.
+		 */
+		if (total && (flags & MEM_CGROUP_RECLAIM_SHRINK))
+			break;
+		if (mem_cgroup_margin(memcg))
+			break;
+		/*
+		 * If nothing was reclaimed after two attempts, there
+		 * may be no reclaimable pages in this hierarchy.
+		 */
+		if (loop && !total)
+			break;
+	}
+	return total;
+}
+
+/**
+ * test_mem_cgroup_node_reclaimable
+ * @mem: the target memcg
+ * @nid: the node ID to be checked.
+ * @noswap : specify true here if the user wants flle only information.
+ *
+ * This function returns whether the specified memcg contains any
+ * reclaimable pages on a node. Returns true if there are any reclaimable
+ * pages in the node.
+ */
+static bool test_mem_cgroup_node_reclaimable(struct mem_cgroup *memcg,
+		int nid, bool noswap)
+{
+	if (mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL_FILE))
+		return true;
+	if (noswap || !total_swap_pages)
+		return false;
+	if (mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL_ANON))
+		return true;
+	return false;
+
+}
+#if MAX_NUMNODES > 1
+
+/*
+ * Always updating the nodemask is not very good - even if we have an empty
+ * list or the wrong list here, we can start from some node and traverse all
+ * nodes based on the zonelist. So update the list loosely once per 10 secs.
+ *
+ */
+static void mem_cgroup_may_update_nodemask(struct mem_cgroup *memcg)
+{
+	int nid;
+	/*
+	 * numainfo_events > 0 means there was at least NUMAINFO_EVENTS_TARGET
+	 * pagein/pageout changes since the last update.
+	 */
+	if (!atomic_read(&memcg->numainfo_events))
+		return;
+	if (atomic_inc_return(&memcg->numainfo_updating) > 1)
+		return;
+
+	/* make a nodemask where this memcg uses memory from */
+	memcg->scan_nodes = node_states[N_HIGH_MEMORY];
+
+	for_each_node_mask(nid, node_states[N_HIGH_MEMORY]) {
+
+		if (!test_mem_cgroup_node_reclaimable(memcg, nid, false))
+			node_clear(nid, memcg->scan_nodes);
+	}
+
+	atomic_set(&memcg->numainfo_events, 0);
+	atomic_set(&memcg->numainfo_updating, 0);
+}
+
+/*
+ * Selecting a node where we start reclaim from. Because what we need is just
+ * reducing usage counter, start from anywhere is O,K. Considering
+ * memory reclaim from current node, there are pros. and cons.
+ *
+ * Freeing memory from current node means freeing memory from a node which
+ * we'll use or we've used. So, it may make LRU bad. And if several threads
+ * hit limits, it will see a contention on a node. But freeing from remote
+ * node means more costs for memory reclaim because of memory latency.
+ *
+ * Now, we use round-robin. Better algorithm is welcomed.
+ */
+int mem_cgroup_select_victim_node(struct mem_cgroup *memcg)
+{
+	int node;
+
+	mem_cgroup_may_update_nodemask(memcg);
+	node = memcg->last_scanned_node;
+
+	node = next_node(node, memcg->scan_nodes);
+	if (node == MAX_NUMNODES)
+		node = first_node(memcg->scan_nodes);
+	/*
+	 * We call this when we hit limit, not when pages are added to LRU.
+	 * No LRU may hold pages because all pages are UNEVICTABLE or
+	 * memcg is too small and all pages are not on LRU. In that case,
+	 * we use curret node.
+	 */
+	if (unlikely(node == MAX_NUMNODES))
+		node = numa_node_id();
+
+	memcg->last_scanned_node = node;
+	return node;
+}
+
+/*
+ * Check all nodes whether it contains reclaimable pages or not.
+ * For quick scan, we make use of scan_nodes. This will allow us to skip
+ * unused nodes. But scan_nodes is lazily updated and may not cotain
+ * enough new information. We need to do double check.
+ */
+bool mem_cgroup_reclaimable(struct mem_cgroup *memcg, bool noswap)
+{
+	int nid;
+
+	/*
+	 * quick check...making use of scan_node.
+	 * We can skip unused nodes.
+	 */
+	if (!nodes_empty(memcg->scan_nodes)) {
+		for (nid = first_node(memcg->scan_nodes);
+		     nid < MAX_NUMNODES;
+		     nid = next_node(nid, memcg->scan_nodes)) {
+
+			if (test_mem_cgroup_node_reclaimable(memcg, nid, noswap))
+				return true;
+		}
+	}
+	/*
+	 * Check rest of nodes.
+	 */
+	for_each_node_state(nid, N_HIGH_MEMORY) {
+		if (node_isset(nid, memcg->scan_nodes))
+			continue;
+		if (test_mem_cgroup_node_reclaimable(memcg, nid, noswap))
+			return true;
+	}
+	return false;
+}
+
+#else
+int mem_cgroup_select_victim_node(struct mem_cgroup *memcg)
+{
+	return 0;
+}
+
+bool mem_cgroup_reclaimable(struct mem_cgroup *memcg, bool noswap)
+{
+	return test_mem_cgroup_node_reclaimable(memcg, 0, noswap);
+}
+#endif
+
+static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg,
+				   struct zone *zone,
+				   gfp_t gfp_mask,
+				   unsigned long *total_scanned)
+{
+	struct mem_cgroup *victim = NULL;
+	int total = 0;
+	int loop = 0;
+	unsigned long excess;
+	unsigned long nr_scanned;
+	struct mem_cgroup_reclaim_cookie reclaim = {
+		.zone = zone,
+		.priority = 0,
+	};
+
+	excess = res_counter_soft_limit_excess(&root_memcg->res) >> PAGE_SHIFT;
+
+	while (1) {
+		victim = mem_cgroup_iter(root_memcg, victim, &reclaim);
+		if (!victim) {
+			loop++;
+			if (loop >= 2) {
+				/*
+				 * If we have not been able to reclaim
+				 * anything, it might because there are
+				 * no reclaimable pages under this hierarchy
+				 */
+				if (!total)
+					break;
+				/*
+				 * We want to do more targeted reclaim.
+				 * excess >> 2 is not to excessive so as to
+				 * reclaim too much, nor too less that we keep
+				 * coming back to reclaim from this cgroup
+				 */
+				if (total >= (excess >> 2) ||
+					(loop > MEM_CGROUP_MAX_RECLAIM_LOOPS))
+					break;
+			}
+			continue;
+		}
+		if (!mem_cgroup_reclaimable(victim, false))
+			continue;
+		total += mem_cgroup_shrink_node_zone(victim, gfp_mask, false,
+						     zone, &nr_scanned);
+		*total_scanned += nr_scanned;
+		if (!res_counter_soft_limit_excess(&root_memcg->res))
+			break;
+	}
+	mem_cgroup_iter_break(root_memcg, victim);
+	return total;
+}
+
+/*
+ * Check OOM-Killer is already running under our hierarchy.
+ * If someone is running, return false.
+ * Has to be called with memcg_oom_lock
+ */
+static bool mem_cgroup_oom_lock(struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *iter, *failed = NULL;
+
+	for_each_mem_cgroup_tree(iter, memcg) {
+		if (iter->oom_lock) {
+			/*
+			 * this subtree of our hierarchy is already locked
+			 * so we cannot give a lock.
+			 */
+			failed = iter;
+			mem_cgroup_iter_break(memcg, iter);
+			break;
+		} else
+			iter->oom_lock = true;
+	}
+
+	if (!failed)
+		return true;
+
+	/*
+	 * OK, we failed to lock the whole subtree so we have to clean up
+	 * what we set up to the failing subtree
+	 */
+	for_each_mem_cgroup_tree(iter, memcg) {
+		if (iter == failed) {
+			mem_cgroup_iter_break(memcg, iter);
+			break;
+		}
+		iter->oom_lock = false;
+	}
+	return false;
+}
+
+/*
+ * Has to be called with memcg_oom_lock
+ */
+static int mem_cgroup_oom_unlock(struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *iter;
+
+	for_each_mem_cgroup_tree(iter, memcg)
+		iter->oom_lock = false;
+	return 0;
+}
+
+static void mem_cgroup_mark_under_oom(struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *iter;
+
+	for_each_mem_cgroup_tree(iter, memcg)
+		atomic_inc(&iter->under_oom);
+}
+
+static void mem_cgroup_unmark_under_oom(struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *iter;
+
+	/*
+	 * When a new child is created while the hierarchy is under oom,
+	 * mem_cgroup_oom_lock() may not be called. We have to use
+	 * atomic_add_unless() here.
+	 */
+	for_each_mem_cgroup_tree(iter, memcg)
+		atomic_add_unless(&iter->under_oom, -1, 0);
+}
+
+static DEFINE_SPINLOCK(memcg_oom_lock);
+static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq);
+
+struct oom_wait_info {
+	struct mem_cgroup *memcg;
+	wait_queue_t	wait;
+};
+
+static int memcg_oom_wake_function(wait_queue_t *wait,
+	unsigned mode, int sync, void *arg)
+{
+	struct mem_cgroup *wake_memcg = (struct mem_cgroup *)arg;
+	struct mem_cgroup *oom_wait_memcg;
+	struct oom_wait_info *oom_wait_info;
+
+	oom_wait_info = container_of(wait, struct oom_wait_info, wait);
+	oom_wait_memcg = oom_wait_info->memcg;
+
+	/*
+	 * Both of oom_wait_info->memcg and wake_memcg are stable under us.
+	 * Then we can use css_is_ancestor without taking care of RCU.
+	 */
+	if (!mem_cgroup_same_or_subtree(oom_wait_memcg, wake_memcg)
+		&& !mem_cgroup_same_or_subtree(wake_memcg, oom_wait_memcg))
+		return 0;
+	return autoremove_wake_function(wait, mode, sync, arg);
+}
+
+static void memcg_wakeup_oom(struct mem_cgroup *memcg)
+{
+	/* for filtering, pass "memcg" as argument. */
+	__wake_up(&memcg_oom_waitq, TASK_NORMAL, 0, memcg);
+}
+
+static void memcg_oom_recover(struct mem_cgroup *memcg)
+{
+	if (memcg && atomic_read(&memcg->under_oom))
+		memcg_wakeup_oom(memcg);
+}
+
+/*
+ * try to call OOM killer. returns false if we should exit memory-reclaim loop.
+ */
+bool mem_cgroup_handle_oom(struct mem_cgroup *memcg, gfp_t mask, int order)
+{
+	struct oom_wait_info owait;
+	bool locked, need_to_kill;
+
+	owait.memcg = memcg;
+	owait.wait.flags = 0;
+	owait.wait.func = memcg_oom_wake_function;
+	owait.wait.private = current;
+	INIT_LIST_HEAD(&owait.wait.task_list);
+	need_to_kill = true;
+	mem_cgroup_mark_under_oom(memcg);
+
+	/* At first, try to OOM lock hierarchy under memcg.*/
+	spin_lock(&memcg_oom_lock);
+	locked = mem_cgroup_oom_lock(memcg);
+	/*
+	 * Even if signal_pending(), we can't quit charge() loop without
+	 * accounting. So, UNINTERRUPTIBLE is appropriate. But SIGKILL
+	 * under OOM is always welcomed, use TASK_KILLABLE here.
+	 */
+	prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE);
+	if (!locked || memcg->oom_kill_disable)
+		need_to_kill = false;
+	if (locked)
+		mem_cgroup_oom_notify(memcg);
+	spin_unlock(&memcg_oom_lock);
+
+	if (need_to_kill) {
+		finish_wait(&memcg_oom_waitq, &owait.wait);
+		mem_cgroup_out_of_memory(memcg, mask, order);
+	} else {
+		schedule();
+		finish_wait(&memcg_oom_waitq, &owait.wait);
+	}
+	spin_lock(&memcg_oom_lock);
+	if (locked)
+		mem_cgroup_oom_unlock(memcg);
+	memcg_wakeup_oom(memcg);
+	spin_unlock(&memcg_oom_lock);
+
+	mem_cgroup_unmark_under_oom(memcg);
+
+	if (test_thread_flag(TIF_MEMDIE) || fatal_signal_pending(current))
+		return false;
+	/* Give chance to dying process */
+	schedule_timeout_uninterruptible(1);
+	return true;
+}
+
+/*
+ * Currently used to update mapped file statistics, but the routine can be
+ * generalized to update other statistics as well.
+ *
+ * Notes: Race condition
+ *
+ * We usually use page_cgroup_lock() for accessing page_cgroup member but
+ * it tends to be costly. But considering some conditions, we doesn't need
+ * to do so _always_.
+ *
+ * Considering "charge", lock_page_cgroup() is not required because all
+ * file-stat operations happen after a page is attached to radix-tree. There
+ * are no race with "charge".
+ *
+ * Considering "uncharge", we know that memcg doesn't clear pc->mem_cgroup
+ * at "uncharge" intentionally. So, we always see valid pc->mem_cgroup even
+ * if there are race with "uncharge". Statistics itself is properly handled
+ * by flags.
+ *
+ * Considering "move", this is an only case we see a race. To make the race
+ * small, we check mm->moving_account and detect there are possibility of race
+ * If there is, we take a lock.
+ */
+
+void __mem_cgroup_begin_update_page_stat(struct page *page,
+				bool *locked, unsigned long *flags)
+{
+	struct mem_cgroup *memcg;
+	struct page_cgroup *pc;
+
+	pc = lookup_page_cgroup(page);
+again:
+	memcg = pc->mem_cgroup;
+	if (unlikely(!memcg || !PageCgroupUsed(pc)))
+		return;
+	/*
+	 * If this memory cgroup is not under account moving, we don't
+	 * need to take move_lock_page_cgroup(). Because we already hold
+	 * rcu_read_lock(), any calls to move_account will be delayed until
+	 * rcu_read_unlock() if mem_cgroup_stolen() == true.
+	 */
+	if (!mem_cgroup_stolen(memcg))
+		return;
+
+	move_lock_mem_cgroup(memcg, flags);
+	if (memcg != pc->mem_cgroup || !PageCgroupUsed(pc)) {
+		move_unlock_mem_cgroup(memcg, flags);
+		goto again;
+	}
+	*locked = true;
+}
+
+void __mem_cgroup_end_update_page_stat(struct page *page, unsigned long *flags)
+{
+	struct page_cgroup *pc = lookup_page_cgroup(page);
+
+	/*
+	 * It's guaranteed that pc->mem_cgroup never changes while
+	 * lock is held because a routine modifies pc->mem_cgroup
+	 * should take move_lock_page_cgroup().
+	 */
+	move_unlock_mem_cgroup(pc->mem_cgroup, flags);
+}
+
+void mem_cgroup_update_page_stat(struct page *page,
+				 enum mem_cgroup_page_stat_item idx, int val)
+{
+	struct mem_cgroup *memcg;
+	struct page_cgroup *pc = lookup_page_cgroup(page);
+	unsigned long uninitialized_var(flags);
+
+	if (mem_cgroup_disabled())
+		return;
+
+	memcg = pc->mem_cgroup;
+	if (unlikely(!memcg || !PageCgroupUsed(pc)))
+		return;
+
+	switch (idx) {
+	case MEMCG_NR_FILE_MAPPED:
+		idx = MEM_CGROUP_STAT_FILE_MAPPED;
+		break;
+	default:
+		BUG();
+	}
+
+	this_cpu_add(memcg->stat->count[idx], val);
+}
+
+/*
+ * size of first charge trial. "32" comes from vmscan.c's magic value.
+ * TODO: maybe necessary to use big numbers in big irons.
+ */
+#define CHARGE_BATCH	32U
+struct memcg_stock_pcp {
+	struct mem_cgroup *cached; /* this never be root cgroup */
+	unsigned int nr_pages;
+	struct work_struct work;
+	unsigned long flags;
+#define FLUSHING_CACHED_CHARGE	(0)
+};
+static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock);
+static DEFINE_MUTEX(percpu_charge_mutex);
+
+/*
+ * Try to consume stocked charge on this cpu. If success, one page is consumed
+ * from local stock and true is returned. If the stock is 0 or charges from a
+ * cgroup which is not current target, returns false. This stock will be
+ * refilled.
+ */
+static bool consume_stock(struct mem_cgroup *memcg)
+{
+	struct memcg_stock_pcp *stock;
+	bool ret = true;
+
+	stock = &get_cpu_var(memcg_stock);
+	if (memcg == stock->cached && stock->nr_pages)
+		stock->nr_pages--;
+	else /* need to call res_counter_charge */
+		ret = false;
+	put_cpu_var(memcg_stock);
+	return ret;
+}
+
+/*
+ * Returns stocks cached in percpu to res_counter and reset cached information.
+ */
+static void drain_stock(struct memcg_stock_pcp *stock)
+{
+	struct mem_cgroup *old = stock->cached;
+
+	if (stock->nr_pages) {
+		unsigned long bytes = stock->nr_pages * PAGE_SIZE;
+
+		res_counter_uncharge(&old->res, bytes);
+		if (do_swap_account)
+			res_counter_uncharge(&old->memsw, bytes);
+		stock->nr_pages = 0;
+	}
+	stock->cached = NULL;
+}
+
+/*
+ * This must be called under preempt disabled or must be called by
+ * a thread which is pinned to local cpu.
+ */
+static void drain_local_stock(struct work_struct *dummy)
+{
+	struct memcg_stock_pcp *stock = &__get_cpu_var(memcg_stock);
+	drain_stock(stock);
+	clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags);
+}
+
+/*
+ * Cache charges(val) which is from res_counter, to local per_cpu area.
+ * This will be consumed by consume_stock() function, later.
+ */
+static void refill_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
+{
+	struct memcg_stock_pcp *stock;
+	int cpu = get_cpu_light();
+
+	stock = &per_cpu(memcg_stock, cpu);
+
+	if (stock->cached != memcg) { /* reset if necessary */
+		drain_stock(stock);
+		stock->cached = memcg;
+	}
+	stock->nr_pages += nr_pages;
+	put_cpu_light();
+}
+
+/*
+ * Drains all per-CPU charge caches for given root_memcg resp. subtree
+ * of the hierarchy under it. sync flag says whether we should block
+ * until the work is done.
+ */
+static void drain_all_stock(struct mem_cgroup *root_memcg, bool sync)
+{
+	int cpu, curcpu;
+
+	/* Notify other cpus that system-wide "drain" is running */
+	get_online_cpus();
+	curcpu = get_cpu_light();
+	for_each_online_cpu(cpu) {
+		struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
+		struct mem_cgroup *memcg;
+
+		memcg = stock->cached;
+		if (!memcg || !stock->nr_pages)
+			continue;
+		if (!mem_cgroup_same_or_subtree(root_memcg, memcg))
+			continue;
+		if (!test_and_set_bit(FLUSHING_CACHED_CHARGE, &stock->flags)) {
+			if (cpu == curcpu)
+				drain_local_stock(&stock->work);
+			else
+				schedule_work_on(cpu, &stock->work);
+		}
+	}
+	put_cpu_light();
+
+	if (!sync)
+		goto out;
+
+	for_each_online_cpu(cpu) {
+		struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
+		if (test_bit(FLUSHING_CACHED_CHARGE, &stock->flags))
+			flush_work(&stock->work);
+	}
+out:
+ 	put_online_cpus();
+}
+
+/*
+ * Tries to drain stocked charges in other cpus. This function is asynchronous
+ * and just put a work per cpu for draining localy on each cpu. Caller can
+ * expects some charges will be back to res_counter later but cannot wait for
+ * it.
+ */
+static void drain_all_stock_async(struct mem_cgroup *root_memcg)
+{
+	/*
+	 * If someone calls draining, avoid adding more kworker runs.
+	 */
+	if (!mutex_trylock(&percpu_charge_mutex))
+		return;
+	drain_all_stock(root_memcg, false);
+	mutex_unlock(&percpu_charge_mutex);
+}
+
+/* This is a synchronous drain interface. */
+static void drain_all_stock_sync(struct mem_cgroup *root_memcg)
+{
+	/* called when force_empty is called */
+	mutex_lock(&percpu_charge_mutex);
+	drain_all_stock(root_memcg, true);
+	mutex_unlock(&percpu_charge_mutex);
+}
+
+/*
+ * This function drains percpu counter value from DEAD cpu and
+ * move it to local cpu. Note that this function can be preempted.
+ */
+static void mem_cgroup_drain_pcp_counter(struct mem_cgroup *memcg, int cpu)
+{
+	int i;
+
+	spin_lock(&memcg->pcp_counter_lock);
+	for (i = 0; i < MEM_CGROUP_STAT_DATA; i++) {
+		long x = per_cpu(memcg->stat->count[i], cpu);
+
+		per_cpu(memcg->stat->count[i], cpu) = 0;
+		memcg->nocpu_base.count[i] += x;
+	}
+	for (i = 0; i < MEM_CGROUP_EVENTS_NSTATS; i++) {
+		unsigned long x = per_cpu(memcg->stat->events[i], cpu);
+
+		per_cpu(memcg->stat->events[i], cpu) = 0;
+		memcg->nocpu_base.events[i] += x;
+	}
+	spin_unlock(&memcg->pcp_counter_lock);
+}
+
+static int __cpuinit memcg_cpu_hotplug_callback(struct notifier_block *nb,
+					unsigned long action,
+					void *hcpu)
+{
+	int cpu = (unsigned long)hcpu;
+	struct memcg_stock_pcp *stock;
+	struct mem_cgroup *iter;
+
+	if (action == CPU_ONLINE)
+		return NOTIFY_OK;
+
+	if (action != CPU_DEAD && action != CPU_DEAD_FROZEN)
+		return NOTIFY_OK;
+
+	for_each_mem_cgroup(iter)
+		mem_cgroup_drain_pcp_counter(iter, cpu);
+
+	stock = &per_cpu(memcg_stock, cpu);
+	drain_stock(stock);
+	return NOTIFY_OK;
+}
+
+
+/* See __mem_cgroup_try_charge() for details */
+enum {
+	CHARGE_OK,		/* success */
+	CHARGE_RETRY,		/* need to retry but retry is not bad */
+	CHARGE_NOMEM,		/* we can't do more. return -ENOMEM */
+	CHARGE_WOULDBLOCK,	/* GFP_WAIT wasn't set and no enough res. */
+	CHARGE_OOM_DIE,		/* the current is killed because of OOM */
+};
+
+static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
+				unsigned int nr_pages, bool oom_check)
+{
+	unsigned long csize = nr_pages * PAGE_SIZE;
+	struct mem_cgroup *mem_over_limit;
+	struct res_counter *fail_res;
+	unsigned long flags = 0;
+	int ret;
+
+	ret = res_counter_charge(&memcg->res, csize, &fail_res);
+
+	if (likely(!ret)) {
+		if (!do_swap_account)
+			return CHARGE_OK;
+		ret = res_counter_charge(&memcg->memsw, csize, &fail_res);
+		if (likely(!ret))
+			return CHARGE_OK;
+
+		res_counter_uncharge(&memcg->res, csize);
+		mem_over_limit = mem_cgroup_from_res_counter(fail_res, memsw);
+		flags |= MEM_CGROUP_RECLAIM_NOSWAP;
+	} else
+		mem_over_limit = mem_cgroup_from_res_counter(fail_res, res);
+	/*
+	 * nr_pages can be either a huge page (HPAGE_PMD_NR), a batch
+	 * of regular pages (CHARGE_BATCH), or a single regular page (1).
+	 *
+	 * Never reclaim on behalf of optional batching, retry with a
+	 * single page instead.
+	 */
+	if (nr_pages == CHARGE_BATCH)
+		return CHARGE_RETRY;
+
+	if (!(gfp_mask & __GFP_WAIT))
+		return CHARGE_WOULDBLOCK;
+
+	ret = mem_cgroup_reclaim(mem_over_limit, gfp_mask, flags);
+	if (mem_cgroup_margin(mem_over_limit) >= nr_pages)
+		return CHARGE_RETRY;
+	/*
+	 * Even though the limit is exceeded at this point, reclaim
+	 * may have been able to free some pages.  Retry the charge
+	 * before killing the task.
+	 *
+	 * Only for regular pages, though: huge pages are rather
+	 * unlikely to succeed so close to the limit, and we fall back
+	 * to regular pages anyway in case of failure.
+	 */
+	if (nr_pages == 1 && ret)
+		return CHARGE_RETRY;
+
+	/*
+	 * At task move, charge accounts can be doubly counted. So, it's
+	 * better to wait until the end of task_move if something is going on.
+	 */
+	if (mem_cgroup_wait_acct_move(mem_over_limit))
+		return CHARGE_RETRY;
+
+	/* If we don't need to call oom-killer at el, return immediately */
+	if (!oom_check)
+		return CHARGE_NOMEM;
+	/* check OOM */
+	if (!mem_cgroup_handle_oom(mem_over_limit, gfp_mask, get_order(csize)))
+		return CHARGE_OOM_DIE;
+
+	return CHARGE_RETRY;
+}
+
+/*
+ * __mem_cgroup_try_charge() does
+ * 1. detect memcg to be charged against from passed *mm and *ptr,
+ * 2. update res_counter
+ * 3. call memory reclaim if necessary.
+ *
+ * In some special case, if the task is fatal, fatal_signal_pending() or
+ * has TIF_MEMDIE, this function returns -EINTR while writing root_mem_cgroup
+ * to *ptr. There are two reasons for this. 1: fatal threads should quit as soon
+ * as possible without any hazards. 2: all pages should have a valid
+ * pc->mem_cgroup. If mm is NULL and the caller doesn't pass a valid memcg
+ * pointer, that is treated as a charge to root_mem_cgroup.
+ *
+ * So __mem_cgroup_try_charge() will return
+ *  0       ...  on success, filling *ptr with a valid memcg pointer.
+ *  -ENOMEM ...  charge failure because of resource limits.
+ *  -EINTR  ...  if thread is fatal. *ptr is filled with root_mem_cgroup.
+ *
+ * Unlike the exported interface, an "oom" parameter is added. if oom==true,
+ * the oom-killer can be invoked.
+ */
+static int __mem_cgroup_try_charge(struct mm_struct *mm,
+				   gfp_t gfp_mask,
+				   unsigned int nr_pages,
+				   struct mem_cgroup **ptr,
+				   bool oom)
+{
+	unsigned int batch = max(CHARGE_BATCH, nr_pages);
+	int nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES;
+	struct mem_cgroup *memcg = NULL;
+	int ret;
+
+	/*
+	 * Unlike gloval-vm's OOM-kill, we're not in memory shortage
+	 * in system level. So, allow to go ahead dying process in addition to
+	 * MEMDIE process.
+	 */
+	if (unlikely(test_thread_flag(TIF_MEMDIE)
+		     || fatal_signal_pending(current)))
+		goto bypass;
+
+	/*
+	 * We always charge the cgroup the mm_struct belongs to.
+	 * The mm_struct's mem_cgroup changes on task migration if the
+	 * thread group leader migrates. It's possible that mm is not
+	 * set, if so charge the init_mm (happens for pagecache usage).
+	 */
+	if (!*ptr && !mm)
+		*ptr = root_mem_cgroup;
+again:
+	if (*ptr) { /* css should be a valid one */
+		memcg = *ptr;
+		VM_BUG_ON(css_is_removed(&memcg->css));
+		if (mem_cgroup_is_root(memcg))
+			goto done;
+		if (nr_pages == 1 && consume_stock(memcg))
+			goto done;
+		css_get(&memcg->css);
+	} else {
+		struct task_struct *p;
+
+		rcu_read_lock();
+		p = rcu_dereference(mm->owner);
+		/*
+		 * Because we don't have task_lock(), "p" can exit.
+		 * In that case, "memcg" can point to root or p can be NULL with
+		 * race with swapoff. Then, we have small risk of mis-accouning.
+		 * But such kind of mis-account by race always happens because
+		 * we don't have cgroup_mutex(). It's overkill and we allo that
+		 * small race, here.
+		 * (*) swapoff at el will charge against mm-struct not against
+		 * task-struct. So, mm->owner can be NULL.
+		 */
+		memcg = mem_cgroup_from_task(p);
+		if (!memcg)
+			memcg = root_mem_cgroup;
+		if (mem_cgroup_is_root(memcg)) {
+			rcu_read_unlock();
+			goto done;
+		}
+		if (nr_pages == 1 && consume_stock(memcg)) {
+			/*
+			 * It seems dagerous to access memcg without css_get().
+			 * But considering how consume_stok works, it's not
+			 * necessary. If consume_stock success, some charges
+			 * from this memcg are cached on this cpu. So, we
+			 * don't need to call css_get()/css_tryget() before
+			 * calling consume_stock().
+			 */
+			rcu_read_unlock();
+			goto done;
+		}
+		/* after here, we may be blocked. we need to get refcnt */
+		if (!css_tryget(&memcg->css)) {
+			rcu_read_unlock();
+			goto again;
+		}
+		rcu_read_unlock();
+	}
+
+	do {
+		bool oom_check;
+
+		/* If killed, bypass charge */
+		if (fatal_signal_pending(current)) {
+			css_put(&memcg->css);
+			goto bypass;
+		}
+
+		oom_check = false;
+		if (oom && !nr_oom_retries) {
+			oom_check = true;
+			nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES;
+		}
+
+		ret = mem_cgroup_do_charge(memcg, gfp_mask, batch, oom_check);
+		switch (ret) {
+		case CHARGE_OK:
+			break;
+		case CHARGE_RETRY: /* not in OOM situation but retry */
+			batch = nr_pages;
+			css_put(&memcg->css);
+			memcg = NULL;
+			goto again;
+		case CHARGE_WOULDBLOCK: /* !__GFP_WAIT */
+			css_put(&memcg->css);
+			goto nomem;
+		case CHARGE_NOMEM: /* OOM routine works */
+			if (!oom) {
+				css_put(&memcg->css);
+				goto nomem;
+			}
+			/* If oom, we never return -ENOMEM */
+			nr_oom_retries--;
+			break;
+		case CHARGE_OOM_DIE: /* Killed by OOM Killer */
+			css_put(&memcg->css);
+			goto bypass;
+		}
+	} while (ret != CHARGE_OK);
+
+	if (batch > nr_pages)
+		refill_stock(memcg, batch - nr_pages);
+	css_put(&memcg->css);
+done:
+	*ptr = memcg;
+	return 0;
+nomem:
+	*ptr = NULL;
+	return -ENOMEM;
+bypass:
+	*ptr = root_mem_cgroup;
+	return -EINTR;
+}
+
+/*
+ * Somemtimes we have to undo a charge we got by try_charge().
+ * This function is for that and do uncharge, put css's refcnt.
+ * gotten by try_charge().
+ */
+static void __mem_cgroup_cancel_charge(struct mem_cgroup *memcg,
+				       unsigned int nr_pages)
+{
+	if (!mem_cgroup_is_root(memcg)) {
+		unsigned long bytes = nr_pages * PAGE_SIZE;
+
+		res_counter_uncharge(&memcg->res, bytes);
+		if (do_swap_account)
+			res_counter_uncharge(&memcg->memsw, bytes);
+	}
+}
+
+/*
+ * A helper function to get mem_cgroup from ID. must be called under
+ * rcu_read_lock(). The caller must check css_is_removed() or some if
+ * it's concern. (dropping refcnt from swap can be called against removed
+ * memcg.)
+ */
+static struct mem_cgroup *mem_cgroup_lookup(unsigned short id)
+{
+	struct cgroup_subsys_state *css;
+
+	/* ID 0 is unused ID */
+	if (!id)
+		return NULL;
+	css = css_lookup(&mem_cgroup_subsys, id);
+	if (!css)
+		return NULL;
+	return container_of(css, struct mem_cgroup, css);
+}
+
+struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
+{
+	struct mem_cgroup *memcg = NULL;
+	struct page_cgroup *pc;
+	unsigned short id;
+	swp_entry_t ent;
+
+	VM_BUG_ON(!PageLocked(page));
+
+	pc = lookup_page_cgroup(page);
+	lock_page_cgroup(pc);
+	if (PageCgroupUsed(pc)) {
+		memcg = pc->mem_cgroup;
+		if (memcg && !css_tryget(&memcg->css))
+			memcg = NULL;
+	} else if (PageSwapCache(page)) {
+		ent.val = page_private(page);
+		id = lookup_swap_cgroup_id(ent);
+		rcu_read_lock();
+		memcg = mem_cgroup_lookup(id);
+		if (memcg && !css_tryget(&memcg->css))
+			memcg = NULL;
+		rcu_read_unlock();
+	}
+	unlock_page_cgroup(pc);
+	return memcg;
+}
+
+static void __mem_cgroup_commit_charge(struct mem_cgroup *memcg,
+				       struct page *page,
+				       unsigned int nr_pages,
+				       enum charge_type ctype,
+				       bool lrucare)
+{
+	struct page_cgroup *pc = lookup_page_cgroup(page);
+	struct zone *uninitialized_var(zone);
+	bool was_on_lru = false;
+	bool anon;
+
+	lock_page_cgroup(pc);
+	if (unlikely(PageCgroupUsed(pc))) {
+		unlock_page_cgroup(pc);
+		__mem_cgroup_cancel_charge(memcg, nr_pages);
+		return;
+	}
+	/*
+	 * we don't need page_cgroup_lock about tail pages, becase they are not
+	 * accessed by any other context at this point.
+	 */
+
+	/*
+	 * In some cases, SwapCache and FUSE(splice_buf->radixtree), the page
+	 * may already be on some other mem_cgroup's LRU.  Take care of it.
+	 */
+	if (lrucare) {
+		zone = page_zone(page);
+		spin_lock_irq(&zone->lru_lock);
+		if (PageLRU(page)) {
+			ClearPageLRU(page);
+			del_page_from_lru_list(zone, page, page_lru(page));
+			was_on_lru = true;
+		}
+	}
+
+	pc->mem_cgroup = memcg;
+	/*
+	 * We access a page_cgroup asynchronously without lock_page_cgroup().
+	 * Especially when a page_cgroup is taken from a page, pc->mem_cgroup
+	 * is accessed after testing USED bit. To make pc->mem_cgroup visible
+	 * before USED bit, we need memory barrier here.
+	 * See mem_cgroup_add_lru_list(), etc.
+ 	 */
+	smp_wmb();
+	SetPageCgroupUsed(pc);
+
+	if (lrucare) {
+		if (was_on_lru) {
+			VM_BUG_ON(PageLRU(page));
+			SetPageLRU(page);
+			add_page_to_lru_list(zone, page, page_lru(page));
+		}
+		spin_unlock_irq(&zone->lru_lock);
+	}
+
+	if (ctype == MEM_CGROUP_CHARGE_TYPE_MAPPED)
+		anon = true;
+	else
+		anon = false;
+
+	mem_cgroup_charge_statistics(memcg, anon, nr_pages);
+	unlock_page_cgroup(pc);
+
+	/*
+	 * "charge_statistics" updated event counter. Then, check it.
+	 * Insert ancestor (and ancestor's ancestors), to softlimit RB-tree.
+	 * if they exceeds softlimit.
+	 */
+	memcg_check_events(memcg, page);
+}
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+
+#define PCGF_NOCOPY_AT_SPLIT ((1 << PCG_LOCK) | (1 << PCG_MIGRATION))
+/*
+ * Because tail pages are not marked as "used", set it. We're under
+ * zone->lru_lock, 'splitting on pmd' and compound_lock.
+ * charge/uncharge will be never happen and move_account() is done under
+ * compound_lock(), so we don't have to take care of races.
+ */
+void mem_cgroup_split_huge_fixup(struct page *head)
+{
+	struct page_cgroup *head_pc = lookup_page_cgroup(head);
+	struct page_cgroup *pc;
+	int i;
+
+	if (mem_cgroup_disabled())
+		return;
+	for (i = 1; i < HPAGE_PMD_NR; i++) {
+		pc = head_pc + i;
+		pc->mem_cgroup = head_pc->mem_cgroup;
+		smp_wmb();/* see __commit_charge() */
+		pc->flags = head_pc->flags & ~PCGF_NOCOPY_AT_SPLIT;
+	}
+}
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+
+/**
+ * mem_cgroup_move_account - move account of the page
+ * @page: the page
+ * @nr_pages: number of regular pages (>1 for huge pages)
+ * @pc:	page_cgroup of the page.
+ * @from: mem_cgroup which the page is moved from.
+ * @to:	mem_cgroup which the page is moved to. @from != @to.
+ * @uncharge: whether we should call uncharge and css_put against @from.
+ *
+ * The caller must confirm following.
+ * - page is not on LRU (isolate_page() is useful.)
+ * - compound_lock is held when nr_pages > 1
+ *
+ * This function doesn't do "charge" nor css_get to new cgroup. It should be
+ * done by a caller(__mem_cgroup_try_charge would be useful). If @uncharge is
+ * true, this function does "uncharge" from old cgroup, but it doesn't if
+ * @uncharge is false, so a caller should do "uncharge".
+ */
+static int mem_cgroup_move_account(struct page *page,
+				   unsigned int nr_pages,
+				   struct page_cgroup *pc,
+				   struct mem_cgroup *from,
+				   struct mem_cgroup *to,
+				   bool uncharge)
+{
+	unsigned long flags;
+	int ret;
+	bool anon = PageAnon(page);
+
+	VM_BUG_ON(from == to);
+	VM_BUG_ON(PageLRU(page));
+	/*
+	 * The page is isolated from LRU. So, collapse function
+	 * will not handle this page. But page splitting can happen.
+	 * Do this check under compound_page_lock(). The caller should
+	 * hold it.
+	 */
+	ret = -EBUSY;
+	if (nr_pages > 1 && !PageTransHuge(page))
+		goto out;
+
+	lock_page_cgroup(pc);
+
+	ret = -EINVAL;
+	if (!PageCgroupUsed(pc) || pc->mem_cgroup != from)
+		goto unlock;
+
+	move_lock_mem_cgroup(from, &flags);
+
+	if (!anon && page_mapped(page)) {
+		/* Update mapped_file data for mem_cgroup */
+		preempt_disable();
+		__this_cpu_dec(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
+		__this_cpu_inc(to->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
+		preempt_enable();
+	}
+	mem_cgroup_charge_statistics(from, anon, -nr_pages);
+	if (uncharge)
+		/* This is not "cancel", but cancel_charge does all we need. */
+		__mem_cgroup_cancel_charge(from, nr_pages);
+
+	/* caller should have done css_get */
+	pc->mem_cgroup = to;
+	mem_cgroup_charge_statistics(to, anon, nr_pages);
+	/*
+	 * We charges against "to" which may not have any tasks. Then, "to"
+	 * can be under rmdir(). But in current implementation, caller of
+	 * this function is just force_empty() and move charge, so it's
+	 * guaranteed that "to" is never removed. So, we don't check rmdir
+	 * status here.
+	 */
+	move_unlock_mem_cgroup(from, &flags);
+	ret = 0;
+unlock:
+	unlock_page_cgroup(pc);
+	/*
+	 * check events
+	 */
+	memcg_check_events(to, page);
+	memcg_check_events(from, page);
+out:
+	return ret;
+}
+
+/*
+ * move charges to its parent.
+ */
+
+static int mem_cgroup_move_parent(struct page *page,
+				  struct page_cgroup *pc,
+				  struct mem_cgroup *child,
+				  gfp_t gfp_mask)
+{
+	struct cgroup *cg = child->css.cgroup;
+	struct cgroup *pcg = cg->parent;
+	struct mem_cgroup *parent;
+	unsigned int nr_pages;
+	unsigned long uninitialized_var(flags);
+	int ret;
+
+	/* Is ROOT ? */
+	if (!pcg)
+		return -EINVAL;
+
+	ret = -EBUSY;
+	if (!get_page_unless_zero(page))
+		goto out;
+	if (isolate_lru_page(page))
+		goto put;
+
+	nr_pages = hpage_nr_pages(page);
+
+	parent = mem_cgroup_from_cont(pcg);
+	ret = __mem_cgroup_try_charge(NULL, gfp_mask, nr_pages, &parent, false);
+	if (ret)
+		goto put_back;
+
+	if (nr_pages > 1)
+		flags = compound_lock_irqsave(page);
+
+	ret = mem_cgroup_move_account(page, nr_pages, pc, child, parent, true);
+	if (ret)
+		__mem_cgroup_cancel_charge(parent, nr_pages);
+
+	if (nr_pages > 1)
+		compound_unlock_irqrestore(page, flags);
+put_back:
+	putback_lru_page(page);
+put:
+	put_page(page);
+out:
+	return ret;
+}
+
+/*
+ * Charge the memory controller for page usage.
+ * Return
+ * 0 if the charge was successful
+ * < 0 if the cgroup is over its limit
+ */
+static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
+				gfp_t gfp_mask, enum charge_type ctype)
+{
+	struct mem_cgroup *memcg = NULL;
+	unsigned int nr_pages = 1;
+	bool oom = true;
+	int ret;
+
+	if (PageTransHuge(page)) {
+		nr_pages <<= compound_order(page);
+		VM_BUG_ON(!PageTransHuge(page));
+		/*
+		 * Never OOM-kill a process for a huge page.  The
+		 * fault handler will fall back to regular pages.
+		 */
+		oom = false;
+	}
+
+	ret = __mem_cgroup_try_charge(mm, gfp_mask, nr_pages, &memcg, oom);
+	if (ret == -ENOMEM)
+		return ret;
+	__mem_cgroup_commit_charge(memcg, page, nr_pages, ctype, false);
+	return 0;
+}
+
+int mem_cgroup_newpage_charge(struct page *page,
+			      struct mm_struct *mm, gfp_t gfp_mask)
+{
+	if (mem_cgroup_disabled())
+		return 0;
+	VM_BUG_ON(page_mapped(page));
+	VM_BUG_ON(page->mapping && !PageAnon(page));
+	VM_BUG_ON(!mm);
+	return mem_cgroup_charge_common(page, mm, gfp_mask,
+					MEM_CGROUP_CHARGE_TYPE_MAPPED);
+}
+
+static void
+__mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr,
+					enum charge_type ctype);
+
+int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
+				gfp_t gfp_mask)
+{
+	struct mem_cgroup *memcg = NULL;
+	enum charge_type type = MEM_CGROUP_CHARGE_TYPE_CACHE;
+	int ret;
+
+	if (mem_cgroup_disabled())
+		return 0;
+	if (PageCompound(page))
+		return 0;
+
+	if (unlikely(!mm))
+		mm = &init_mm;
+	if (!page_is_file_cache(page))
+		type = MEM_CGROUP_CHARGE_TYPE_SHMEM;
+
+	if (!PageSwapCache(page))
+		ret = mem_cgroup_charge_common(page, mm, gfp_mask, type);
+	else { /* page is swapcache/shmem */
+		ret = mem_cgroup_try_charge_swapin(mm, page, gfp_mask, &memcg);
+		if (!ret)
+			__mem_cgroup_commit_charge_swapin(page, memcg, type);
+	}
+	return ret;
+}
+
+/*
+ * While swap-in, try_charge -> commit or cancel, the page is locked.
+ * And when try_charge() successfully returns, one refcnt to memcg without
+ * struct page_cgroup is acquired. This refcnt will be consumed by
+ * "commit()" or removed by "cancel()"
+ */
+int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
+				 struct page *page,
+				 gfp_t mask, struct mem_cgroup **memcgp)
+{
+	struct mem_cgroup *memcg;
+	int ret;
+
+	*memcgp = NULL;
+
+	if (mem_cgroup_disabled())
+		return 0;
+
+	if (!do_swap_account)
+		goto charge_cur_mm;
+	/*
+	 * A racing thread's fault, or swapoff, may have already updated
+	 * the pte, and even removed page from swap cache: in those cases
+	 * do_swap_page()'s pte_same() test will fail; but there's also a
+	 * KSM case which does need to charge the page.
+	 */
+	if (!PageSwapCache(page))
+		goto charge_cur_mm;
+	memcg = try_get_mem_cgroup_from_page(page);
+	if (!memcg)
+		goto charge_cur_mm;
+	*memcgp = memcg;
+	ret = __mem_cgroup_try_charge(NULL, mask, 1, memcgp, true);
+	css_put(&memcg->css);
+	if (ret == -EINTR)
+		ret = 0;
+	return ret;
+charge_cur_mm:
+	if (unlikely(!mm))
+		mm = &init_mm;
+	ret = __mem_cgroup_try_charge(mm, mask, 1, memcgp, true);
+	if (ret == -EINTR)
+		ret = 0;
+	return ret;
+}
+
+static void
+__mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *memcg,
+					enum charge_type ctype)
+{
+	if (mem_cgroup_disabled())
+		return;
+	if (!memcg)
+		return;
+	cgroup_exclude_rmdir(&memcg->css);
+
+	__mem_cgroup_commit_charge(memcg, page, 1, ctype, true);
+	/*
+	 * Now swap is on-memory. This means this page may be
+	 * counted both as mem and swap....double count.
+	 * Fix it by uncharging from memsw. Basically, this SwapCache is stable
+	 * under lock_page(). But in do_swap_page()::memory.c, reuse_swap_page()
+	 * may call delete_from_swap_cache() before reach here.
+	 */
+	if (do_swap_account && PageSwapCache(page)) {
+		swp_entry_t ent = {.val = page_private(page)};
+		struct mem_cgroup *swap_memcg;
+		unsigned short id;
+
+		id = swap_cgroup_record(ent, 0);
+		rcu_read_lock();
+		swap_memcg = mem_cgroup_lookup(id);
+		if (swap_memcg) {
+			/*
+			 * This recorded memcg can be obsolete one. So, avoid
+			 * calling css_tryget
+			 */
+			if (!mem_cgroup_is_root(swap_memcg))
+				res_counter_uncharge(&swap_memcg->memsw,
+						     PAGE_SIZE);
+			mem_cgroup_swap_statistics(swap_memcg, false);
+			mem_cgroup_put(swap_memcg);
+		}
+		rcu_read_unlock();
+	}
+	/*
+	 * At swapin, we may charge account against cgroup which has no tasks.
+	 * So, rmdir()->pre_destroy() can be called while we do this charge.
+	 * In that case, we need to call pre_destroy() again. check it here.
+	 */
+	cgroup_release_and_wakeup_rmdir(&memcg->css);
+}
+
+void mem_cgroup_commit_charge_swapin(struct page *page,
+				     struct mem_cgroup *memcg)
+{
+	__mem_cgroup_commit_charge_swapin(page, memcg,
+					  MEM_CGROUP_CHARGE_TYPE_MAPPED);
+}
+
+void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *memcg)
+{
+	if (mem_cgroup_disabled())
+		return;
+	if (!memcg)
+		return;
+	__mem_cgroup_cancel_charge(memcg, 1);
+}
+
+static void mem_cgroup_do_uncharge(struct mem_cgroup *memcg,
+				   unsigned int nr_pages,
+				   const enum charge_type ctype)
+{
+	struct memcg_batch_info *batch = NULL;
+	bool uncharge_memsw = true;
+
+	/* If swapout, usage of swap doesn't decrease */
+	if (!do_swap_account || ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
+		uncharge_memsw = false;
+
+	batch = &current->memcg_batch;
+	/*
+	 * In usual, we do css_get() when we remember memcg pointer.
+	 * But in this case, we keep res->usage until end of a series of
+	 * uncharges. Then, it's ok to ignore memcg's refcnt.
+	 */
+	if (!batch->memcg)
+		batch->memcg = memcg;
+	/*
+	 * do_batch > 0 when unmapping pages or inode invalidate/truncate.
+	 * In those cases, all pages freed continuously can be expected to be in
+	 * the same cgroup and we have chance to coalesce uncharges.
+	 * But we do uncharge one by one if this is killed by OOM(TIF_MEMDIE)
+	 * because we want to do uncharge as soon as possible.
+	 */
+
+	if (!batch->do_batch || test_thread_flag(TIF_MEMDIE))
+		goto direct_uncharge;
+
+	if (nr_pages > 1)
+		goto direct_uncharge;
+
+	/*
+	 * In typical case, batch->memcg == mem. This means we can
+	 * merge a series of uncharges to an uncharge of res_counter.
+	 * If not, we uncharge res_counter ony by one.
+	 */
+	if (batch->memcg != memcg)
+		goto direct_uncharge;
+	/* remember freed charge and uncharge it later */
+	batch->nr_pages++;
+	if (uncharge_memsw)
+		batch->memsw_nr_pages++;
+	return;
+direct_uncharge:
+	res_counter_uncharge(&memcg->res, nr_pages * PAGE_SIZE);
+	if (uncharge_memsw)
+		res_counter_uncharge(&memcg->memsw, nr_pages * PAGE_SIZE);
+	if (unlikely(batch->memcg != memcg))
+		memcg_oom_recover(memcg);
+}
+
+/*
+ * uncharge if !page_mapped(page)
+ */
+static struct mem_cgroup *
+__mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
+{
+	struct mem_cgroup *memcg = NULL;
+	unsigned int nr_pages = 1;
+	struct page_cgroup *pc;
+	bool anon;
+
+	if (mem_cgroup_disabled())
+		return NULL;
+
+	if (PageSwapCache(page))
+		return NULL;
+
+	if (PageTransHuge(page)) {
+		nr_pages <<= compound_order(page);
+		VM_BUG_ON(!PageTransHuge(page));
+	}
+	/*
+	 * Check if our page_cgroup is valid
+	 */
+	pc = lookup_page_cgroup(page);
+	if (unlikely(!PageCgroupUsed(pc)))
+		return NULL;
+
+	lock_page_cgroup(pc);
+
+	memcg = pc->mem_cgroup;
+
+	if (!PageCgroupUsed(pc))
+		goto unlock_out;
+
+	anon = PageAnon(page);
+
+	switch (ctype) {
+	case MEM_CGROUP_CHARGE_TYPE_MAPPED:
+		/*
+		 * Generally PageAnon tells if it's the anon statistics to be
+		 * updated; but sometimes e.g. mem_cgroup_uncharge_page() is
+		 * used before page reached the stage of being marked PageAnon.
+		 */
+		anon = true;
+		/* fallthrough */
+	case MEM_CGROUP_CHARGE_TYPE_DROP:
+		/* See mem_cgroup_prepare_migration() */
+		if (page_mapped(page) || PageCgroupMigration(pc))
+			goto unlock_out;
+		break;
+	case MEM_CGROUP_CHARGE_TYPE_SWAPOUT:
+		if (!PageAnon(page)) {	/* Shared memory */
+			if (page->mapping && !page_is_file_cache(page))
+				goto unlock_out;
+		} else if (page_mapped(page)) /* Anon */
+				goto unlock_out;
+		break;
+	default:
+		break;
+	}
+
+	mem_cgroup_charge_statistics(memcg, anon, -nr_pages);
+
+	ClearPageCgroupUsed(pc);
+	/*
+	 * pc->mem_cgroup is not cleared here. It will be accessed when it's
+	 * freed from LRU. This is safe because uncharged page is expected not
+	 * to be reused (freed soon). Exception is SwapCache, it's handled by
+	 * special functions.
+	 */
+
+	unlock_page_cgroup(pc);
+	/*
+	 * even after unlock, we have memcg->res.usage here and this memcg
+	 * will never be freed.
+	 */
+	memcg_check_events(memcg, page);
+	if (do_swap_account && ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT) {
+		mem_cgroup_swap_statistics(memcg, true);
+		mem_cgroup_get(memcg);
+	}
+	if (!mem_cgroup_is_root(memcg))
+		mem_cgroup_do_uncharge(memcg, nr_pages, ctype);
+
+	return memcg;
+
+unlock_out:
+	unlock_page_cgroup(pc);
+	return NULL;
+}
+
+void mem_cgroup_uncharge_page(struct page *page)
+{
+	/* early check. */
+	if (page_mapped(page))
+		return;
+	VM_BUG_ON(page->mapping && !PageAnon(page));
+	__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_MAPPED);
+}
+
+void mem_cgroup_uncharge_cache_page(struct page *page)
+{
+	VM_BUG_ON(page_mapped(page));
+	VM_BUG_ON(page->mapping);
+	__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE);
+}
+
+/*
+ * Batch_start/batch_end is called in unmap_page_range/invlidate/trucate.
+ * In that cases, pages are freed continuously and we can expect pages
+ * are in the same memcg. All these calls itself limits the number of
+ * pages freed at once, then uncharge_start/end() is called properly.
+ * This may be called prural(2) times in a context,
+ */
+
+void mem_cgroup_uncharge_start(void)
+{
+	current->memcg_batch.do_batch++;
+	/* We can do nest. */
+	if (current->memcg_batch.do_batch == 1) {
+		current->memcg_batch.memcg = NULL;
+		current->memcg_batch.nr_pages = 0;
+		current->memcg_batch.memsw_nr_pages = 0;
+	}
+}
+
+void mem_cgroup_uncharge_end(void)
+{
+	struct memcg_batch_info *batch = &current->memcg_batch;
+
+	if (!batch->do_batch)
+		return;
+
+	batch->do_batch--;
+	if (batch->do_batch) /* If stacked, do nothing. */
+		return;
+
+	if (!batch->memcg)
+		return;
+	/*
+	 * This "batch->memcg" is valid without any css_get/put etc...
+	 * bacause we hide charges behind us.
+	 */
+	if (batch->nr_pages)
+		res_counter_uncharge(&batch->memcg->res,
+				     batch->nr_pages * PAGE_SIZE);
+	if (batch->memsw_nr_pages)
+		res_counter_uncharge(&batch->memcg->memsw,
+				     batch->memsw_nr_pages * PAGE_SIZE);
+	memcg_oom_recover(batch->memcg);
+	/* forget this pointer (for sanity check) */
+	batch->memcg = NULL;
+}
+
+#ifdef CONFIG_SWAP
+/*
+ * called after __delete_from_swap_cache() and drop "page" account.
+ * memcg information is recorded to swap_cgroup of "ent"
+ */
+void
+mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
+{
+	struct mem_cgroup *memcg;
+	int ctype = MEM_CGROUP_CHARGE_TYPE_SWAPOUT;
+
+	if (!swapout) /* this was a swap cache but the swap is unused ! */
+		ctype = MEM_CGROUP_CHARGE_TYPE_DROP;
+
+	memcg = __mem_cgroup_uncharge_common(page, ctype);
+
+	/*
+	 * record memcg information,  if swapout && memcg != NULL,
+	 * mem_cgroup_get() was called in uncharge().
+	 */
+	if (do_swap_account && swapout && memcg)
+		swap_cgroup_record(ent, css_id(&memcg->css));
+}
+#endif
+
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
+/*
+ * called from swap_entry_free(). remove record in swap_cgroup and
+ * uncharge "memsw" account.
+ */
+void mem_cgroup_uncharge_swap(swp_entry_t ent)
+{
+	struct mem_cgroup *memcg;
+	unsigned short id;
+
+	if (!do_swap_account)
+		return;
+
+	id = swap_cgroup_record(ent, 0);
+	rcu_read_lock();
+	memcg = mem_cgroup_lookup(id);
+	if (memcg) {
+		/*
+		 * We uncharge this because swap is freed.
+		 * This memcg can be obsolete one. We avoid calling css_tryget
+		 */
+		if (!mem_cgroup_is_root(memcg))
+			res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
+		mem_cgroup_swap_statistics(memcg, false);
+		mem_cgroup_put(memcg);
+	}
+	rcu_read_unlock();
+}
+
+/**
+ * mem_cgroup_move_swap_account - move swap charge and swap_cgroup's record.
+ * @entry: swap entry to be moved
+ * @from:  mem_cgroup which the entry is moved from
+ * @to:  mem_cgroup which the entry is moved to
+ * @need_fixup: whether we should fixup res_counters and refcounts.
+ *
+ * It succeeds only when the swap_cgroup's record for this entry is the same
+ * as the mem_cgroup's id of @from.
+ *
+ * Returns 0 on success, -EINVAL on failure.
+ *
+ * The caller must have charged to @to, IOW, called res_counter_charge() about
+ * both res and memsw, and called css_get().
+ */
+static int mem_cgroup_move_swap_account(swp_entry_t entry,
+		struct mem_cgroup *from, struct mem_cgroup *to, bool need_fixup)
+{
+	unsigned short old_id, new_id;
+
+	old_id = css_id(&from->css);
+	new_id = css_id(&to->css);
+
+	if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) {
+		mem_cgroup_swap_statistics(from, false);
+		mem_cgroup_swap_statistics(to, true);
+		/*
+		 * This function is only called from task migration context now.
+		 * It postpones res_counter and refcount handling till the end
+		 * of task migration(mem_cgroup_clear_mc()) for performance
+		 * improvement. But we cannot postpone mem_cgroup_get(to)
+		 * because if the process that has been moved to @to does
+		 * swap-in, the refcount of @to might be decreased to 0.
+		 */
+		mem_cgroup_get(to);
+		if (need_fixup) {
+			if (!mem_cgroup_is_root(from))
+				res_counter_uncharge(&from->memsw, PAGE_SIZE);
+			mem_cgroup_put(from);
+			/*
+			 * we charged both to->res and to->memsw, so we should
+			 * uncharge to->res.
+			 */
+			if (!mem_cgroup_is_root(to))
+				res_counter_uncharge(&to->res, PAGE_SIZE);
+		}
+		return 0;
+	}
+	return -EINVAL;
+}
+#else
+static inline int mem_cgroup_move_swap_account(swp_entry_t entry,
+		struct mem_cgroup *from, struct mem_cgroup *to, bool need_fixup)
+{
+	return -EINVAL;
+}
+#endif
+
+/*
+ * Before starting migration, account PAGE_SIZE to mem_cgroup that the old
+ * page belongs to.
+ */
+int mem_cgroup_prepare_migration(struct page *page,
+	struct page *newpage, struct mem_cgroup **memcgp, gfp_t gfp_mask)
+{
+	struct mem_cgroup *memcg = NULL;
+	struct page_cgroup *pc;
+	enum charge_type ctype;
+	int ret = 0;
+
+	*memcgp = NULL;
+
+	VM_BUG_ON(PageTransHuge(page));
+	if (mem_cgroup_disabled())
+		return 0;
+
+	pc = lookup_page_cgroup(page);
+	lock_page_cgroup(pc);
+	if (PageCgroupUsed(pc)) {
+		memcg = pc->mem_cgroup;
+		css_get(&memcg->css);
+		/*
+		 * At migrating an anonymous page, its mapcount goes down
+		 * to 0 and uncharge() will be called. But, even if it's fully
+		 * unmapped, migration may fail and this page has to be
+		 * charged again. We set MIGRATION flag here and delay uncharge
+		 * until end_migration() is called
+		 *
+		 * Corner Case Thinking
+		 * A)
+		 * When the old page was mapped as Anon and it's unmap-and-freed
+		 * while migration was ongoing.
+		 * If unmap finds the old page, uncharge() of it will be delayed
+		 * until end_migration(). If unmap finds a new page, it's
+		 * uncharged when it make mapcount to be 1->0. If unmap code
+		 * finds swap_migration_entry, the new page will not be mapped
+		 * and end_migration() will find it(mapcount==0).
+		 *
+		 * B)
+		 * When the old page was mapped but migraion fails, the kernel
+		 * remaps it. A charge for it is kept by MIGRATION flag even
+		 * if mapcount goes down to 0. We can do remap successfully
+		 * without charging it again.
+		 *
+		 * C)
+		 * The "old" page is under lock_page() until the end of
+		 * migration, so, the old page itself will not be swapped-out.
+		 * If the new page is swapped out before end_migraton, our
+		 * hook to usual swap-out path will catch the event.
+		 */
+		if (PageAnon(page))
+			SetPageCgroupMigration(pc);
+	}
+	unlock_page_cgroup(pc);
+	/*
+	 * If the page is not charged at this point,
+	 * we return here.
+	 */
+	if (!memcg)
+		return 0;
+
+	*memcgp = memcg;
+	ret = __mem_cgroup_try_charge(NULL, gfp_mask, 1, memcgp, false);
+	css_put(&memcg->css);/* drop extra refcnt */
+	if (ret) {
+		if (PageAnon(page)) {
+			lock_page_cgroup(pc);
+			ClearPageCgroupMigration(pc);
+			unlock_page_cgroup(pc);
+			/*
+			 * The old page may be fully unmapped while we kept it.
+			 */
+			mem_cgroup_uncharge_page(page);
+		}
+		/* we'll need to revisit this error code (we have -EINTR) */
+		return -ENOMEM;
+	}
+	/*
+	 * We charge new page before it's used/mapped. So, even if unlock_page()
+	 * is called before end_migration, we can catch all events on this new
+	 * page. In the case new page is migrated but not remapped, new page's
+	 * mapcount will be finally 0 and we call uncharge in end_migration().
+	 */
+	if (PageAnon(page))
+		ctype = MEM_CGROUP_CHARGE_TYPE_MAPPED;
+	else if (page_is_file_cache(page))
+		ctype = MEM_CGROUP_CHARGE_TYPE_CACHE;
+	else
+		ctype = MEM_CGROUP_CHARGE_TYPE_SHMEM;
+	__mem_cgroup_commit_charge(memcg, newpage, 1, ctype, false);
+	return ret;
+}
+
+/* remove redundant charge if migration failed*/
+void mem_cgroup_end_migration(struct mem_cgroup *memcg,
+	struct page *oldpage, struct page *newpage, bool migration_ok)
+{
+	struct page *used, *unused;
+	struct page_cgroup *pc;
+	bool anon;
+
+	if (!memcg)
+		return;
+	/* blocks rmdir() */
+	cgroup_exclude_rmdir(&memcg->css);
+	if (!migration_ok) {
+		used = oldpage;
+		unused = newpage;
+	} else {
+		used = newpage;
+		unused = oldpage;
+	}
+	/*
+	 * We disallowed uncharge of pages under migration because mapcount
+	 * of the page goes down to zero, temporarly.
+	 * Clear the flag and check the page should be charged.
+	 */
+	pc = lookup_page_cgroup(oldpage);
+	lock_page_cgroup(pc);
+	ClearPageCgroupMigration(pc);
+	unlock_page_cgroup(pc);
+	anon = PageAnon(used);
+	__mem_cgroup_uncharge_common(unused,
+		anon ? MEM_CGROUP_CHARGE_TYPE_MAPPED
+		     : MEM_CGROUP_CHARGE_TYPE_CACHE);
+
+	/*
+	 * If a page is a file cache, radix-tree replacement is very atomic
+	 * and we can skip this check. When it was an Anon page, its mapcount
+	 * goes down to 0. But because we added MIGRATION flage, it's not
+	 * uncharged yet. There are several case but page->mapcount check
+	 * and USED bit check in mem_cgroup_uncharge_page() will do enough
+	 * check. (see prepare_charge() also)
+	 */
+	if (anon)
+		mem_cgroup_uncharge_page(used);
+	/*
+	 * At migration, we may charge account against cgroup which has no
+	 * tasks.
+	 * So, rmdir()->pre_destroy() can be called while we do this charge.
+	 * In that case, we need to call pre_destroy() again. check it here.
+	 */
+	cgroup_release_and_wakeup_rmdir(&memcg->css);
+}
+
+/*
+ * At replace page cache, newpage is not under any memcg but it's on
+ * LRU. So, this function doesn't touch res_counter but handles LRU
+ * in correct way. Both pages are locked so we cannot race with uncharge.
+ */
+void mem_cgroup_replace_page_cache(struct page *oldpage,
+				  struct page *newpage)
+{
+	struct mem_cgroup *memcg;
+	struct page_cgroup *pc;
+	enum charge_type type = MEM_CGROUP_CHARGE_TYPE_CACHE;
+
+	if (mem_cgroup_disabled())
+		return;
+
+	pc = lookup_page_cgroup(oldpage);
+	/* fix accounting on old pages */
+	lock_page_cgroup(pc);
+	memcg = pc->mem_cgroup;
+	mem_cgroup_charge_statistics(memcg, false, -1);
+	ClearPageCgroupUsed(pc);
+	unlock_page_cgroup(pc);
+
+	if (PageSwapBacked(oldpage))
+		type = MEM_CGROUP_CHARGE_TYPE_SHMEM;
+
+	/*
+	 * Even if newpage->mapping was NULL before starting replacement,
+	 * the newpage may be on LRU(or pagevec for LRU) already. We lock
+	 * LRU while we overwrite pc->mem_cgroup.
+	 */
+	__mem_cgroup_commit_charge(memcg, newpage, 1, type, true);
+}
+
+#ifdef CONFIG_DEBUG_VM
+static struct page_cgroup *lookup_page_cgroup_used(struct page *page)
+{
+	struct page_cgroup *pc;
+
+	pc = lookup_page_cgroup(page);
+	/*
+	 * Can be NULL while feeding pages into the page allocator for
+	 * the first time, i.e. during boot or memory hotplug;
+	 * or when mem_cgroup_disabled().
+	 */
+	if (likely(pc) && PageCgroupUsed(pc))
+		return pc;
+	return NULL;
+}
+
+bool mem_cgroup_bad_page_check(struct page *page)
+{
+	if (mem_cgroup_disabled())
+		return false;
+
+	return lookup_page_cgroup_used(page) != NULL;
+}
+
+void mem_cgroup_print_bad_page(struct page *page)
+{
+	struct page_cgroup *pc;
+
+	pc = lookup_page_cgroup_used(page);
+	if (pc) {
+		printk(KERN_ALERT "pc:%p pc->flags:%lx pc->mem_cgroup:%p\n",
+		       pc, pc->flags, pc->mem_cgroup);
+	}
+}
+#endif
+
+static DEFINE_MUTEX(set_limit_mutex);
+
+static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
+				unsigned long long val)
+{
+	int retry_count;
+	u64 memswlimit, memlimit;
+	int ret = 0;
+	int children = mem_cgroup_count_children(memcg);
+	u64 curusage, oldusage;
+	int enlarge;
+
+	/*
+	 * For keeping hierarchical_reclaim simple, how long we should retry
+	 * is depends on callers. We set our retry-count to be function
+	 * of # of children which we should visit in this loop.
+	 */
+	retry_count = MEM_CGROUP_RECLAIM_RETRIES * children;
+
+	oldusage = res_counter_read_u64(&memcg->res, RES_USAGE);
+
+	enlarge = 0;
+	while (retry_count) {
+		if (signal_pending(current)) {
+			ret = -EINTR;
+			break;
+		}
+		/*
+		 * Rather than hide all in some function, I do this in
+		 * open coded manner. You see what this really does.
+		 * We have to guarantee memcg->res.limit < memcg->memsw.limit.
+		 */
+		mutex_lock(&set_limit_mutex);
+		memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
+		if (memswlimit < val) {
+			ret = -EINVAL;
+			mutex_unlock(&set_limit_mutex);
+			break;
+		}
+
+		memlimit = res_counter_read_u64(&memcg->res, RES_LIMIT);
+		if (memlimit < val)
+			enlarge = 1;
+
+		ret = res_counter_set_limit(&memcg->res, val);
+		if (!ret) {
+			if (memswlimit == val)
+				memcg->memsw_is_minimum = true;
+			else
+				memcg->memsw_is_minimum = false;
+		}
+		mutex_unlock(&set_limit_mutex);
+
+		if (!ret)
+			break;
+
+		mem_cgroup_reclaim(memcg, GFP_KERNEL,
+				   MEM_CGROUP_RECLAIM_SHRINK);
+		curusage = res_counter_read_u64(&memcg->res, RES_USAGE);
+		/* Usage is reduced ? */
+  		if (curusage >= oldusage)
+			retry_count--;
+		else
+			oldusage = curusage;
+	}
+	if (!ret && enlarge)
+		memcg_oom_recover(memcg);
+
+	return ret;
+}
+
+static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
+					unsigned long long val)
+{
+	int retry_count;
+	u64 memlimit, memswlimit, oldusage, curusage;
+	int children = mem_cgroup_count_children(memcg);
+	int ret = -EBUSY;
+	int enlarge = 0;
+
+	/* see mem_cgroup_resize_res_limit */
+ 	retry_count = children * MEM_CGROUP_RECLAIM_RETRIES;
+	oldusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
+	while (retry_count) {
+		if (signal_pending(current)) {
+			ret = -EINTR;
+			break;
+		}
+		/*
+		 * Rather than hide all in some function, I do this in
+		 * open coded manner. You see what this really does.
+		 * We have to guarantee memcg->res.limit < memcg->memsw.limit.
+		 */
+		mutex_lock(&set_limit_mutex);
+		memlimit = res_counter_read_u64(&memcg->res, RES_LIMIT);
+		if (memlimit > val) {
+			ret = -EINVAL;
+			mutex_unlock(&set_limit_mutex);
+			break;
+		}
+		memswlimit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
+		if (memswlimit < val)
+			enlarge = 1;
+		ret = res_counter_set_limit(&memcg->memsw, val);
+		if (!ret) {
+			if (memlimit == val)
+				memcg->memsw_is_minimum = true;
+			else
+				memcg->memsw_is_minimum = false;
+		}
+		mutex_unlock(&set_limit_mutex);
+
+		if (!ret)
+			break;
+
+		mem_cgroup_reclaim(memcg, GFP_KERNEL,
+				   MEM_CGROUP_RECLAIM_NOSWAP |
+				   MEM_CGROUP_RECLAIM_SHRINK);
+		curusage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
+		/* Usage is reduced ? */
+		if (curusage >= oldusage)
+			retry_count--;
+		else
+			oldusage = curusage;
+	}
+	if (!ret && enlarge)
+		memcg_oom_recover(memcg);
+	return ret;
+}
+
+unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
+					    gfp_t gfp_mask,
+					    unsigned long *total_scanned)
+{
+	unsigned long nr_reclaimed = 0;
+	struct mem_cgroup_per_zone *mz, *next_mz = NULL;
+	unsigned long reclaimed;
+	int loop = 0;
+	struct mem_cgroup_tree_per_zone *mctz;
+	unsigned long long excess;
+	unsigned long nr_scanned;
+
+	if (order > 0)
+		return 0;
+
+	mctz = soft_limit_tree_node_zone(zone_to_nid(zone), zone_idx(zone));
+	/*
+	 * This loop can run a while, specially if mem_cgroup's continuously
+	 * keep exceeding their soft limit and putting the system under
+	 * pressure
+	 */
+	do {
+		if (next_mz)
+			mz = next_mz;
+		else
+			mz = mem_cgroup_largest_soft_limit_node(mctz);
+		if (!mz)
+			break;
+
+		nr_scanned = 0;
+		reclaimed = mem_cgroup_soft_reclaim(mz->memcg, zone,
+						    gfp_mask, &nr_scanned);
+		nr_reclaimed += reclaimed;
+		*total_scanned += nr_scanned;
+		spin_lock(&mctz->lock);
+
+		/*
+		 * If we failed to reclaim anything from this memory cgroup
+		 * it is time to move on to the next cgroup
+		 */
+		next_mz = NULL;
+		if (!reclaimed) {
+			do {
+				/*
+				 * Loop until we find yet another one.
+				 *
+				 * By the time we get the soft_limit lock
+				 * again, someone might have aded the
+				 * group back on the RB tree. Iterate to
+				 * make sure we get a different mem.
+				 * mem_cgroup_largest_soft_limit_node returns
+				 * NULL if no other cgroup is present on
+				 * the tree
+				 */
+				next_mz =
+				__mem_cgroup_largest_soft_limit_node(mctz);
+				if (next_mz == mz)
+					css_put(&next_mz->memcg->css);
+				else /* next_mz == NULL or other memcg */
+					break;
+			} while (1);
+		}
+		__mem_cgroup_remove_exceeded(mz->memcg, mz, mctz);
+		excess = res_counter_soft_limit_excess(&mz->memcg->res);
+		/*
+		 * One school of thought says that we should not add
+		 * back the node to the tree if reclaim returns 0.
+		 * But our reclaim could return 0, simply because due
+		 * to priority we are exposing a smaller subset of
+		 * memory to reclaim from. Consider this as a longer
+		 * term TODO.
+		 */
+		/* If excess == 0, no tree ops */
+		__mem_cgroup_insert_exceeded(mz->memcg, mz, mctz, excess);
+		spin_unlock(&mctz->lock);
+		css_put(&mz->memcg->css);
+		loop++;
+		/*
+		 * Could not reclaim anything and there are no more
+		 * mem cgroups to try or we seem to be looping without
+		 * reclaiming anything.
+		 */
+		if (!nr_reclaimed &&
+			(next_mz == NULL ||
+			loop > MEM_CGROUP_MAX_SOFT_LIMIT_RECLAIM_LOOPS))
+			break;
+	} while (!nr_reclaimed);
+	if (next_mz)
+		css_put(&next_mz->memcg->css);
+	return nr_reclaimed;
+}
+
+/*
+ * This routine traverse page_cgroup in given list and drop them all.
+ * *And* this routine doesn't reclaim page itself, just removes page_cgroup.
+ */
+static int mem_cgroup_force_empty_list(struct mem_cgroup *memcg,
+				int node, int zid, enum lru_list lru)
+{
+	struct mem_cgroup_per_zone *mz;
+	unsigned long flags, loop;
+	struct list_head *list;
+	struct page *busy;
+	struct zone *zone;
+	int ret = 0;
+
+	zone = &NODE_DATA(node)->node_zones[zid];
+	mz = mem_cgroup_zoneinfo(memcg, node, zid);
+	list = &mz->lruvec.lists[lru];
+
+	loop = mz->lru_size[lru];
+	/* give some margin against EBUSY etc...*/
+	loop += 256;
+	busy = NULL;
+	while (loop--) {
+		struct page_cgroup *pc;
+		struct page *page;
+
+		ret = 0;
+		spin_lock_irqsave(&zone->lru_lock, flags);
+		if (list_empty(list)) {
+			spin_unlock_irqrestore(&zone->lru_lock, flags);
+			break;
+		}
+		page = list_entry(list->prev, struct page, lru);
+		if (busy == page) {
+			list_move(&page->lru, list);
+			busy = NULL;
+			spin_unlock_irqrestore(&zone->lru_lock, flags);
+			continue;
+		}
+		spin_unlock_irqrestore(&zone->lru_lock, flags);
+
+		pc = lookup_page_cgroup(page);
+
+		ret = mem_cgroup_move_parent(page, pc, memcg, GFP_KERNEL);
+		if (ret == -ENOMEM || ret == -EINTR)
+			break;
+
+		if (ret == -EBUSY || ret == -EINVAL) {
+			/* found lock contention or "pc" is obsolete. */
+			busy = page;
+			cond_resched();
+		} else
+			busy = NULL;
+	}
+
+	if (!ret && !list_empty(list))
+		return -EBUSY;
+	return ret;
+}
+
+/*
+ * make mem_cgroup's charge to be 0 if there is no task.
+ * This enables deleting this mem_cgroup.
+ */
+static int mem_cgroup_force_empty(struct mem_cgroup *memcg, bool free_all)
+{
+	int ret;
+	int node, zid, shrink;
+	int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
+	struct cgroup *cgrp = memcg->css.cgroup;
+
+	css_get(&memcg->css);
+
+	shrink = 0;
+	/* should free all ? */
+	if (free_all)
+		goto try_to_free;
+move_account:
+	do {
+		ret = -EBUSY;
+		if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children))
+			goto out;
+		ret = -EINTR;
+		if (signal_pending(current))
+			goto out;
+		/* This is for making all *used* pages to be on LRU. */
+		lru_add_drain_all();
+		drain_all_stock_sync(memcg);
+		ret = 0;
+		mem_cgroup_start_move(memcg);
+		for_each_node_state(node, N_HIGH_MEMORY) {
+			for (zid = 0; !ret && zid < MAX_NR_ZONES; zid++) {
+				enum lru_list lru;
+				for_each_lru(lru) {
+					ret = mem_cgroup_force_empty_list(memcg,
+							node, zid, lru);
+					if (ret)
+						break;
+				}
+			}
+			if (ret)
+				break;
+		}
+		mem_cgroup_end_move(memcg);
+		memcg_oom_recover(memcg);
+		/* it seems parent cgroup doesn't have enough mem */
+		if (ret == -ENOMEM)
+			goto try_to_free;
+		cond_resched();
+	/* "ret" should also be checked to ensure all lists are empty. */
+	} while (res_counter_read_u64(&memcg->res, RES_USAGE) > 0 || ret);
+out:
+	css_put(&memcg->css);
+	return ret;
+
+try_to_free:
+	/* returns EBUSY if there is a task or if we come here twice. */
+	if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children) || shrink) {
+		ret = -EBUSY;
+		goto out;
+	}
+	/* we call try-to-free pages for make this cgroup empty */
+	lru_add_drain_all();
+	/* try to free all pages in this cgroup */
+	shrink = 1;
+	while (nr_retries && res_counter_read_u64(&memcg->res, RES_USAGE) > 0) {
+		int progress;
+
+		if (signal_pending(current)) {
+			ret = -EINTR;
+			goto out;
+		}
+		progress = try_to_free_mem_cgroup_pages(memcg, GFP_KERNEL,
+						false);
+		if (!progress) {
+			nr_retries--;
+			/* maybe some writeback is necessary */
+			congestion_wait(BLK_RW_ASYNC, HZ/10);
+		}
+
+	}
+	lru_add_drain();
+	/* try move_account...there may be some *locked* pages. */
+	goto move_account;
+}
+
+int mem_cgroup_force_empty_write(struct cgroup *cont, unsigned int event)
+{
+	return mem_cgroup_force_empty(mem_cgroup_from_cont(cont), true);
+}
+
+
+static u64 mem_cgroup_hierarchy_read(struct cgroup *cont, struct cftype *cft)
+{
+	return mem_cgroup_from_cont(cont)->use_hierarchy;
+}
+
+static int mem_cgroup_hierarchy_write(struct cgroup *cont, struct cftype *cft,
+					u64 val)
+{
+	int retval = 0;
+	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+	struct cgroup *parent = cont->parent;
+	struct mem_cgroup *parent_memcg = NULL;
+
+	if (parent)
+		parent_memcg = mem_cgroup_from_cont(parent);
+
+	cgroup_lock();
+	/*
+	 * If parent's use_hierarchy is set, we can't make any modifications
+	 * in the child subtrees. If it is unset, then the change can
+	 * occur, provided the current cgroup has no children.
+	 *
+	 * For the root cgroup, parent_mem is NULL, we allow value to be
+	 * set if there are no children.
+	 */
+	if ((!parent_memcg || !parent_memcg->use_hierarchy) &&
+				(val == 1 || val == 0)) {
+		if (list_empty(&cont->children))
+			memcg->use_hierarchy = val;
+		else
+			retval = -EBUSY;
+	} else
+		retval = -EINVAL;
+	cgroup_unlock();
+
+	return retval;
+}
+
+
+static unsigned long mem_cgroup_recursive_stat(struct mem_cgroup *memcg,
+					       enum mem_cgroup_stat_index idx)
+{
+	struct mem_cgroup *iter;
+	long val = 0;
+
+	/* Per-cpu values can be negative, use a signed accumulator */
+	for_each_mem_cgroup_tree(iter, memcg)
+		val += mem_cgroup_read_stat(iter, idx);
+
+	if (val < 0) /* race ? */
+		val = 0;
+	return val;
+}
+
+static inline u64 mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
+{
+	u64 val;
+
+	if (!mem_cgroup_is_root(memcg)) {
+		if (!swap)
+			return res_counter_read_u64(&memcg->res, RES_USAGE);
+		else
+			return res_counter_read_u64(&memcg->memsw, RES_USAGE);
+	}
+
+	val = mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_CACHE);
+	val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_RSS);
+
+	if (swap)
+		val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_SWAPOUT);
+
+	return val << PAGE_SHIFT;
+}
+
+static u64 mem_cgroup_read(struct cgroup *cont, struct cftype *cft)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+	u64 val;
+	int type, name;
+
+	type = MEMFILE_TYPE(cft->private);
+	name = MEMFILE_ATTR(cft->private);
+	switch (type) {
+	case _MEM:
+		if (name == RES_USAGE)
+			val = mem_cgroup_usage(memcg, false);
+		else
+			val = res_counter_read_u64(&memcg->res, name);
+		break;
+	case _MEMSWAP:
+		if (name == RES_USAGE)
+			val = mem_cgroup_usage(memcg, true);
+		else
+			val = res_counter_read_u64(&memcg->memsw, name);
+		break;
+	default:
+		BUG();
+	}
+	return val;
+}
+/*
+ * The user of this function is...
+ * RES_LIMIT.
+ */
+static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
+			    const char *buffer)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+	int type, name;
+	unsigned long long val;
+	int ret;
+
+	type = MEMFILE_TYPE(cft->private);
+	name = MEMFILE_ATTR(cft->private);
+	switch (name) {
+	case RES_LIMIT:
+		if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */
+			ret = -EINVAL;
+			break;
+		}
+		/* This function does all necessary parse...reuse it */
+		ret = res_counter_memparse_write_strategy(buffer, &val);
+		if (ret)
+			break;
+		if (type == _MEM)
+			ret = mem_cgroup_resize_limit(memcg, val);
+		else
+			ret = mem_cgroup_resize_memsw_limit(memcg, val);
+		break;
+	case RES_SOFT_LIMIT:
+		ret = res_counter_memparse_write_strategy(buffer, &val);
+		if (ret)
+			break;
+		/*
+		 * For memsw, soft limits are hard to implement in terms
+		 * of semantics, for now, we support soft limits for
+		 * control without swap
+		 */
+		if (type == _MEM)
+			ret = res_counter_set_soft_limit(&memcg->res, val);
+		else
+			ret = -EINVAL;
+		break;
+	default:
+		ret = -EINVAL; /* should be BUG() ? */
+		break;
+	}
+	return ret;
+}
+
+static void memcg_get_hierarchical_limit(struct mem_cgroup *memcg,
+		unsigned long long *mem_limit, unsigned long long *memsw_limit)
+{
+	struct cgroup *cgroup;
+	unsigned long long min_limit, min_memsw_limit, tmp;
+
+	min_limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
+	min_memsw_limit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
+	cgroup = memcg->css.cgroup;
+	if (!memcg->use_hierarchy)
+		goto out;
+
+	while (cgroup->parent) {
+		cgroup = cgroup->parent;
+		memcg = mem_cgroup_from_cont(cgroup);
+		if (!memcg->use_hierarchy)
+			break;
+		tmp = res_counter_read_u64(&memcg->res, RES_LIMIT);
+		min_limit = min(min_limit, tmp);
+		tmp = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
+		min_memsw_limit = min(min_memsw_limit, tmp);
+	}
+out:
+	*mem_limit = min_limit;
+	*memsw_limit = min_memsw_limit;
+}
+
+static int mem_cgroup_reset(struct cgroup *cont, unsigned int event)
+{
+	struct mem_cgroup *memcg;
+	int type, name;
+
+	memcg = mem_cgroup_from_cont(cont);
+	type = MEMFILE_TYPE(event);
+	name = MEMFILE_ATTR(event);
+	switch (name) {
+	case RES_MAX_USAGE:
+		if (type == _MEM)
+			res_counter_reset_max(&memcg->res);
+		else
+			res_counter_reset_max(&memcg->memsw);
+		break;
+	case RES_FAILCNT:
+		if (type == _MEM)
+			res_counter_reset_failcnt(&memcg->res);
+		else
+			res_counter_reset_failcnt(&memcg->memsw);
+		break;
+	}
+
+	return 0;
+}
+
+static u64 mem_cgroup_move_charge_read(struct cgroup *cgrp,
+					struct cftype *cft)
+{
+	return mem_cgroup_from_cont(cgrp)->move_charge_at_immigrate;
+}
+
+#ifdef CONFIG_MMU
+static int mem_cgroup_move_charge_write(struct cgroup *cgrp,
+					struct cftype *cft, u64 val)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+
+	if (val >= (1 << NR_MOVE_TYPE))
+		return -EINVAL;
+	/*
+	 * We check this value several times in both in can_attach() and
+	 * attach(), so we need cgroup lock to prevent this value from being
+	 * inconsistent.
+	 */
+	cgroup_lock();
+	memcg->move_charge_at_immigrate = val;
+	cgroup_unlock();
+
+	return 0;
+}
+#else
+static int mem_cgroup_move_charge_write(struct cgroup *cgrp,
+					struct cftype *cft, u64 val)
+{
+	return -ENOSYS;
+}
+#endif
+
+
+/* For read statistics */
+enum {
+	MCS_CACHE,
+	MCS_RSS,
+	MCS_FILE_MAPPED,
+	MCS_PGPGIN,
+	MCS_PGPGOUT,
+	MCS_SWAP,
+	MCS_PGFAULT,
+	MCS_PGMAJFAULT,
+	MCS_INACTIVE_ANON,
+	MCS_ACTIVE_ANON,
+	MCS_INACTIVE_FILE,
+	MCS_ACTIVE_FILE,
+	MCS_UNEVICTABLE,
+	NR_MCS_STAT,
+};
+
+struct mcs_total_stat {
+	s64 stat[NR_MCS_STAT];
+};
+
+struct {
+	char *local_name;
+	char *total_name;
+} memcg_stat_strings[NR_MCS_STAT] = {
+	{"cache", "total_cache"},
+	{"rss", "total_rss"},
+	{"mapped_file", "total_mapped_file"},
+	{"pgpgin", "total_pgpgin"},
+	{"pgpgout", "total_pgpgout"},
+	{"swap", "total_swap"},
+	{"pgfault", "total_pgfault"},
+	{"pgmajfault", "total_pgmajfault"},
+	{"inactive_anon", "total_inactive_anon"},
+	{"active_anon", "total_active_anon"},
+	{"inactive_file", "total_inactive_file"},
+	{"active_file", "total_active_file"},
+	{"unevictable", "total_unevictable"}
+};
+
+
+static void
+mem_cgroup_get_local_stat(struct mem_cgroup *memcg, struct mcs_total_stat *s)
+{
+	s64 val;
+
+	/* per cpu stat */
+	val = mem_cgroup_read_stat(memcg, MEM_CGROUP_STAT_CACHE);
+	s->stat[MCS_CACHE] += val * PAGE_SIZE;
+	val = mem_cgroup_read_stat(memcg, MEM_CGROUP_STAT_RSS);
+	s->stat[MCS_RSS] += val * PAGE_SIZE;
+	val = mem_cgroup_read_stat(memcg, MEM_CGROUP_STAT_FILE_MAPPED);
+	s->stat[MCS_FILE_MAPPED] += val * PAGE_SIZE;
+	val = mem_cgroup_read_events(memcg, MEM_CGROUP_EVENTS_PGPGIN);
+	s->stat[MCS_PGPGIN] += val;
+	val = mem_cgroup_read_events(memcg, MEM_CGROUP_EVENTS_PGPGOUT);
+	s->stat[MCS_PGPGOUT] += val;
+	if (do_swap_account) {
+		val = mem_cgroup_read_stat(memcg, MEM_CGROUP_STAT_SWAPOUT);
+		s->stat[MCS_SWAP] += val * PAGE_SIZE;
+	}
+	val = mem_cgroup_read_events(memcg, MEM_CGROUP_EVENTS_PGFAULT);
+	s->stat[MCS_PGFAULT] += val;
+	val = mem_cgroup_read_events(memcg, MEM_CGROUP_EVENTS_PGMAJFAULT);
+	s->stat[MCS_PGMAJFAULT] += val;
+
+	/* per zone stat */
+	val = mem_cgroup_nr_lru_pages(memcg, BIT(LRU_INACTIVE_ANON));
+	s->stat[MCS_INACTIVE_ANON] += val * PAGE_SIZE;
+	val = mem_cgroup_nr_lru_pages(memcg, BIT(LRU_ACTIVE_ANON));
+	s->stat[MCS_ACTIVE_ANON] += val * PAGE_SIZE;
+	val = mem_cgroup_nr_lru_pages(memcg, BIT(LRU_INACTIVE_FILE));
+	s->stat[MCS_INACTIVE_FILE] += val * PAGE_SIZE;
+	val = mem_cgroup_nr_lru_pages(memcg, BIT(LRU_ACTIVE_FILE));
+	s->stat[MCS_ACTIVE_FILE] += val * PAGE_SIZE;
+	val = mem_cgroup_nr_lru_pages(memcg, BIT(LRU_UNEVICTABLE));
+	s->stat[MCS_UNEVICTABLE] += val * PAGE_SIZE;
+}
+
+static void
+mem_cgroup_get_total_stat(struct mem_cgroup *memcg, struct mcs_total_stat *s)
+{
+	struct mem_cgroup *iter;
+
+	for_each_mem_cgroup_tree(iter, memcg)
+		mem_cgroup_get_local_stat(iter, s);
+}
+
+#ifdef CONFIG_NUMA
+static int mem_control_numa_stat_show(struct seq_file *m, void *arg)
+{
+	int nid;
+	unsigned long total_nr, file_nr, anon_nr, unevictable_nr;
+	unsigned long node_nr;
+	struct cgroup *cont = m->private;
+	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+
+	total_nr = mem_cgroup_nr_lru_pages(memcg, LRU_ALL);
+	seq_printf(m, "total=%lu", total_nr);
+	for_each_node_state(nid, N_HIGH_MEMORY) {
+		node_nr = mem_cgroup_node_nr_lru_pages(memcg, nid, LRU_ALL);
+		seq_printf(m, " N%d=%lu", nid, node_nr);
+	}
+	seq_putc(m, '\n');
+
+	file_nr = mem_cgroup_nr_lru_pages(memcg, LRU_ALL_FILE);
+	seq_printf(m, "file=%lu", file_nr);
+	for_each_node_state(nid, N_HIGH_MEMORY) {
+		node_nr = mem_cgroup_node_nr_lru_pages(memcg, nid,
+				LRU_ALL_FILE);
+		seq_printf(m, " N%d=%lu", nid, node_nr);
+	}
+	seq_putc(m, '\n');
+
+	anon_nr = mem_cgroup_nr_lru_pages(memcg, LRU_ALL_ANON);
+	seq_printf(m, "anon=%lu", anon_nr);
+	for_each_node_state(nid, N_HIGH_MEMORY) {
+		node_nr = mem_cgroup_node_nr_lru_pages(memcg, nid,
+				LRU_ALL_ANON);
+		seq_printf(m, " N%d=%lu", nid, node_nr);
+	}
+	seq_putc(m, '\n');
+
+	unevictable_nr = mem_cgroup_nr_lru_pages(memcg, BIT(LRU_UNEVICTABLE));
+	seq_printf(m, "unevictable=%lu", unevictable_nr);
+	for_each_node_state(nid, N_HIGH_MEMORY) {
+		node_nr = mem_cgroup_node_nr_lru_pages(memcg, nid,
+				BIT(LRU_UNEVICTABLE));
+		seq_printf(m, " N%d=%lu", nid, node_nr);
+	}
+	seq_putc(m, '\n');
+	return 0;
+}
+#endif /* CONFIG_NUMA */
+
+static int mem_control_stat_show(struct cgroup *cont, struct cftype *cft,
+				 struct cgroup_map_cb *cb)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+	struct mcs_total_stat mystat;
+	int i;
+
+	memset(&mystat, 0, sizeof(mystat));
+	mem_cgroup_get_local_stat(memcg, &mystat);
+
+
+	for (i = 0; i < NR_MCS_STAT; i++) {
+		if (i == MCS_SWAP && !do_swap_account)
+			continue;
+		cb->fill(cb, memcg_stat_strings[i].local_name, mystat.stat[i]);
+	}
+
+	/* Hierarchical information */
+	{
+		unsigned long long limit, memsw_limit;
+		memcg_get_hierarchical_limit(memcg, &limit, &memsw_limit);
+		cb->fill(cb, "hierarchical_memory_limit", limit);
+		if (do_swap_account)
+			cb->fill(cb, "hierarchical_memsw_limit", memsw_limit);
+	}
+
+	memset(&mystat, 0, sizeof(mystat));
+	mem_cgroup_get_total_stat(memcg, &mystat);
+	for (i = 0; i < NR_MCS_STAT; i++) {
+		if (i == MCS_SWAP && !do_swap_account)
+			continue;
+		cb->fill(cb, memcg_stat_strings[i].total_name, mystat.stat[i]);
+	}
+
+#ifdef CONFIG_DEBUG_VM
+	{
+		int nid, zid;
+		struct mem_cgroup_per_zone *mz;
+		unsigned long recent_rotated[2] = {0, 0};
+		unsigned long recent_scanned[2] = {0, 0};
+
+		for_each_online_node(nid)
+			for (zid = 0; zid < MAX_NR_ZONES; zid++) {
+				mz = mem_cgroup_zoneinfo(memcg, nid, zid);
+
+				recent_rotated[0] +=
+					mz->reclaim_stat.recent_rotated[0];
+				recent_rotated[1] +=
+					mz->reclaim_stat.recent_rotated[1];
+				recent_scanned[0] +=
+					mz->reclaim_stat.recent_scanned[0];
+				recent_scanned[1] +=
+					mz->reclaim_stat.recent_scanned[1];
+			}
+		cb->fill(cb, "recent_rotated_anon", recent_rotated[0]);
+		cb->fill(cb, "recent_rotated_file", recent_rotated[1]);
+		cb->fill(cb, "recent_scanned_anon", recent_scanned[0]);
+		cb->fill(cb, "recent_scanned_file", recent_scanned[1]);
+	}
+#endif
+
+	return 0;
+}
+
+static u64 mem_cgroup_swappiness_read(struct cgroup *cgrp, struct cftype *cft)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+
+	return mem_cgroup_swappiness(memcg);
+}
+
+static int mem_cgroup_swappiness_write(struct cgroup *cgrp, struct cftype *cft,
+				       u64 val)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+	struct mem_cgroup *parent;
+
+	if (val > 100)
+		return -EINVAL;
+
+	if (cgrp->parent == NULL)
+		return -EINVAL;
+
+	parent = mem_cgroup_from_cont(cgrp->parent);
+
+	cgroup_lock();
+
+	/* If under hierarchy, only empty-root can set this value */
+	if ((parent->use_hierarchy) ||
+	    (memcg->use_hierarchy && !list_empty(&cgrp->children))) {
+		cgroup_unlock();
+		return -EINVAL;
+	}
+
+	memcg->swappiness = val;
+
+	cgroup_unlock();
+
+	return 0;
+}
+
+static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
+{
+	struct mem_cgroup_threshold_ary *t;
+	u64 usage;
+	int i;
+
+	rcu_read_lock();
+	if (!swap)
+		t = rcu_dereference(memcg->thresholds.primary);
+	else
+		t = rcu_dereference(memcg->memsw_thresholds.primary);
+
+	if (!t)
+		goto unlock;
+
+	usage = mem_cgroup_usage(memcg, swap);
+
+	/*
+	 * current_threshold points to threshold just below usage.
+	 * If it's not true, a threshold was crossed after last
+	 * call of __mem_cgroup_threshold().
+	 */
+	i = t->current_threshold;
+
+	/*
+	 * Iterate backward over array of thresholds starting from
+	 * current_threshold and check if a threshold is crossed.
+	 * If none of thresholds below usage is crossed, we read
+	 * only one element of the array here.
+	 */
+	for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--)
+		eventfd_signal(t->entries[i].eventfd, 1);
+
+	/* i = current_threshold + 1 */
+	i++;
+
+	/*
+	 * Iterate forward over array of thresholds starting from
+	 * current_threshold+1 and check if a threshold is crossed.
+	 * If none of thresholds above usage is crossed, we read
+	 * only one element of the array here.
+	 */
+	for (; i < t->size && unlikely(t->entries[i].threshold <= usage); i++)
+		eventfd_signal(t->entries[i].eventfd, 1);
+
+	/* Update current_threshold */
+	t->current_threshold = i - 1;
+unlock:
+	rcu_read_unlock();
+}
+
+static void mem_cgroup_threshold(struct mem_cgroup *memcg)
+{
+	while (memcg) {
+		__mem_cgroup_threshold(memcg, false);
+		if (do_swap_account)
+			__mem_cgroup_threshold(memcg, true);
+
+		memcg = parent_mem_cgroup(memcg);
+	}
+}
+
+static int compare_thresholds(const void *a, const void *b)
+{
+	const struct mem_cgroup_threshold *_a = a;
+	const struct mem_cgroup_threshold *_b = b;
+
+	if (_a->threshold > _b->threshold)
+		return 1;
+
+	if (_a->threshold < _b->threshold)
+		return -1;
+
+	return 0;
+}
+
+static int mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg)
+{
+	struct mem_cgroup_eventfd_list *ev;
+
+	list_for_each_entry(ev, &memcg->oom_notify, list)
+		eventfd_signal(ev->eventfd, 1);
+	return 0;
+}
+
+static void mem_cgroup_oom_notify(struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *iter;
+
+	for_each_mem_cgroup_tree(iter, memcg)
+		mem_cgroup_oom_notify_cb(iter);
+}
+
+static int mem_cgroup_usage_register_event(struct cgroup *cgrp,
+	struct cftype *cft, struct eventfd_ctx *eventfd, const char *args)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+	struct mem_cgroup_thresholds *thresholds;
+	struct mem_cgroup_threshold_ary *new;
+	int type = MEMFILE_TYPE(cft->private);
+	u64 threshold, usage;
+	int i, size, ret;
+
+	ret = res_counter_memparse_write_strategy(args, &threshold);
+	if (ret)
+		return ret;
+
+	mutex_lock(&memcg->thresholds_lock);
+
+	if (type == _MEM)
+		thresholds = &memcg->thresholds;
+	else if (type == _MEMSWAP)
+		thresholds = &memcg->memsw_thresholds;
+	else
+		BUG();
+
+	usage = mem_cgroup_usage(memcg, type == _MEMSWAP);
+
+	/* Check if a threshold crossed before adding a new one */
+	if (thresholds->primary)
+		__mem_cgroup_threshold(memcg, type == _MEMSWAP);
+
+	size = thresholds->primary ? thresholds->primary->size + 1 : 1;
+
+	/* Allocate memory for new array of thresholds */
+	new = kmalloc(sizeof(*new) + size * sizeof(struct mem_cgroup_threshold),
+			GFP_KERNEL);
+	if (!new) {
+		ret = -ENOMEM;
+		goto unlock;
+	}
+	new->size = size;
+
+	/* Copy thresholds (if any) to new array */
+	if (thresholds->primary) {
+		memcpy(new->entries, thresholds->primary->entries, (size - 1) *
+				sizeof(struct mem_cgroup_threshold));
+	}
+
+	/* Add new threshold */
+	new->entries[size - 1].eventfd = eventfd;
+	new->entries[size - 1].threshold = threshold;
+
+	/* Sort thresholds. Registering of new threshold isn't time-critical */
+	sort(new->entries, size, sizeof(struct mem_cgroup_threshold),
+			compare_thresholds, NULL);
+
+	/* Find current threshold */
+	new->current_threshold = -1;
+	for (i = 0; i < size; i++) {
+		if (new->entries[i].threshold < usage) {
+			/*
+			 * new->current_threshold will not be used until
+			 * rcu_assign_pointer(), so it's safe to increment
+			 * it here.
+			 */
+			++new->current_threshold;
+		}
+	}
+
+	/* Free old spare buffer and save old primary buffer as spare */
+	kfree(thresholds->spare);
+	thresholds->spare = thresholds->primary;
+
+	rcu_assign_pointer(thresholds->primary, new);
+
+	/* To be sure that nobody uses thresholds */
+	synchronize_rcu();
+
+unlock:
+	mutex_unlock(&memcg->thresholds_lock);
+
+	return ret;
+}
+
+static void mem_cgroup_usage_unregister_event(struct cgroup *cgrp,
+	struct cftype *cft, struct eventfd_ctx *eventfd)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+	struct mem_cgroup_thresholds *thresholds;
+	struct mem_cgroup_threshold_ary *new;
+	int type = MEMFILE_TYPE(cft->private);
+	u64 usage;
+	int i, j, size;
+
+	mutex_lock(&memcg->thresholds_lock);
+	if (type == _MEM)
+		thresholds = &memcg->thresholds;
+	else if (type == _MEMSWAP)
+		thresholds = &memcg->memsw_thresholds;
+	else
+		BUG();
+
+	if (!thresholds->primary)
+		goto unlock;
+
+	usage = mem_cgroup_usage(memcg, type == _MEMSWAP);
+
+	/* Check if a threshold crossed before removing */
+	__mem_cgroup_threshold(memcg, type == _MEMSWAP);
+
+	/* Calculate new number of threshold */
+	size = 0;
+	for (i = 0; i < thresholds->primary->size; i++) {
+		if (thresholds->primary->entries[i].eventfd != eventfd)
+			size++;
+	}
+
+	new = thresholds->spare;
+
+	/* Set thresholds array to NULL if we don't have thresholds */
+	if (!size) {
+		kfree(new);
+		new = NULL;
+		goto swap_buffers;
+	}
+
+	new->size = size;
+
+	/* Copy thresholds and find current threshold */
+	new->current_threshold = -1;
+	for (i = 0, j = 0; i < thresholds->primary->size; i++) {
+		if (thresholds->primary->entries[i].eventfd == eventfd)
+			continue;
+
+		new->entries[j] = thresholds->primary->entries[i];
+		if (new->entries[j].threshold < usage) {
+			/*
+			 * new->current_threshold will not be used
+			 * until rcu_assign_pointer(), so it's safe to increment
+			 * it here.
+			 */
+			++new->current_threshold;
+		}
+		j++;
+	}
+
+swap_buffers:
+	/* Swap primary and spare array */
+	thresholds->spare = thresholds->primary;
+	/* If all events are unregistered, free the spare array */
+	if (!new) {
+		kfree(thresholds->spare);
+		thresholds->spare = NULL;
+	}
+
+	rcu_assign_pointer(thresholds->primary, new);
+
+	/* To be sure that nobody uses thresholds */
+	synchronize_rcu();
+unlock:
+	mutex_unlock(&memcg->thresholds_lock);
+}
+
+static int mem_cgroup_oom_register_event(struct cgroup *cgrp,
+	struct cftype *cft, struct eventfd_ctx *eventfd, const char *args)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+	struct mem_cgroup_eventfd_list *event;
+	int type = MEMFILE_TYPE(cft->private);
+
+	BUG_ON(type != _OOM_TYPE);
+	event = kmalloc(sizeof(*event),	GFP_KERNEL);
+	if (!event)
+		return -ENOMEM;
+
+	spin_lock(&memcg_oom_lock);
+
+	event->eventfd = eventfd;
+	list_add(&event->list, &memcg->oom_notify);
+
+	/* already in OOM ? */
+	if (atomic_read(&memcg->under_oom))
+		eventfd_signal(eventfd, 1);
+	spin_unlock(&memcg_oom_lock);
+
+	return 0;
+}
+
+static void mem_cgroup_oom_unregister_event(struct cgroup *cgrp,
+	struct cftype *cft, struct eventfd_ctx *eventfd)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+	struct mem_cgroup_eventfd_list *ev, *tmp;
+	int type = MEMFILE_TYPE(cft->private);
+
+	BUG_ON(type != _OOM_TYPE);
+
+	spin_lock(&memcg_oom_lock);
+
+	list_for_each_entry_safe(ev, tmp, &memcg->oom_notify, list) {
+		if (ev->eventfd == eventfd) {
+			list_del(&ev->list);
+			kfree(ev);
+		}
+	}
+
+	spin_unlock(&memcg_oom_lock);
+}
+
+static int mem_cgroup_oom_control_read(struct cgroup *cgrp,
+	struct cftype *cft,  struct cgroup_map_cb *cb)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+
+	cb->fill(cb, "oom_kill_disable", memcg->oom_kill_disable);
+
+	if (atomic_read(&memcg->under_oom))
+		cb->fill(cb, "under_oom", 1);
+	else
+		cb->fill(cb, "under_oom", 0);
+	return 0;
+}
+
+static int mem_cgroup_oom_control_write(struct cgroup *cgrp,
+	struct cftype *cft, u64 val)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
+	struct mem_cgroup *parent;
+
+	/* cannot set to root cgroup and only 0 and 1 are allowed */
+	if (!cgrp->parent || !((val == 0) || (val == 1)))
+		return -EINVAL;
+
+	parent = mem_cgroup_from_cont(cgrp->parent);
+
+	cgroup_lock();
+	/* oom-kill-disable is a flag for subhierarchy. */
+	if ((parent->use_hierarchy) ||
+	    (memcg->use_hierarchy && !list_empty(&cgrp->children))) {
+		cgroup_unlock();
+		return -EINVAL;
+	}
+	memcg->oom_kill_disable = val;
+	if (!val)
+		memcg_oom_recover(memcg);
+	cgroup_unlock();
+	return 0;
+}
+
+#ifdef CONFIG_NUMA
+static const struct file_operations mem_control_numa_stat_file_operations = {
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
+static int mem_control_numa_stat_open(struct inode *unused, struct file *file)
+{
+	struct cgroup *cont = file->f_dentry->d_parent->d_fsdata;
+
+	file->f_op = &mem_control_numa_stat_file_operations;
+	return single_open(file, mem_control_numa_stat_show, cont);
+}
+#endif /* CONFIG_NUMA */
+
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
+static int register_kmem_files(struct cgroup *cont, struct cgroup_subsys *ss)
+{
+	/*
+	 * Part of this would be better living in a separate allocation
+	 * function, leaving us with just the cgroup tree population work.
+	 * We, however, depend on state such as network's proto_list that
+	 * is only initialized after cgroup creation. I found the less
+	 * cumbersome way to deal with it to defer it all to populate time
+	 */
+	return mem_cgroup_sockets_init(cont, ss);
+};
+
+static void kmem_cgroup_destroy(struct cgroup *cont)
+{
+	mem_cgroup_sockets_destroy(cont);
+}
+#else
+static int register_kmem_files(struct cgroup *cont, struct cgroup_subsys *ss)
+{
+	return 0;
+}
+
+static void kmem_cgroup_destroy(struct cgroup *cont)
+{
+}
+#endif
+
+static struct cftype mem_cgroup_files[] = {
+	{
+		.name = "usage_in_bytes",
+		.private = MEMFILE_PRIVATE(_MEM, RES_USAGE),
+		.read_u64 = mem_cgroup_read,
+		.register_event = mem_cgroup_usage_register_event,
+		.unregister_event = mem_cgroup_usage_unregister_event,
+	},
+	{
+		.name = "max_usage_in_bytes",
+		.private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE),
+		.trigger = mem_cgroup_reset,
+		.read_u64 = mem_cgroup_read,
+	},
+	{
+		.name = "limit_in_bytes",
+		.private = MEMFILE_PRIVATE(_MEM, RES_LIMIT),
+		.write_string = mem_cgroup_write,
+		.read_u64 = mem_cgroup_read,
+	},
+	{
+		.name = "soft_limit_in_bytes",
+		.private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT),
+		.write_string = mem_cgroup_write,
+		.read_u64 = mem_cgroup_read,
+	},
+	{
+		.name = "failcnt",
+		.private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT),
+		.trigger = mem_cgroup_reset,
+		.read_u64 = mem_cgroup_read,
+	},
+	{
+		.name = "stat",
+		.read_map = mem_control_stat_show,
+	},
+	{
+		.name = "force_empty",
+		.trigger = mem_cgroup_force_empty_write,
+	},
+	{
+		.name = "use_hierarchy",
+		.write_u64 = mem_cgroup_hierarchy_write,
+		.read_u64 = mem_cgroup_hierarchy_read,
+	},
+	{
+		.name = "swappiness",
+		.read_u64 = mem_cgroup_swappiness_read,
+		.write_u64 = mem_cgroup_swappiness_write,
+	},
+	{
+		.name = "move_charge_at_immigrate",
+		.read_u64 = mem_cgroup_move_charge_read,
+		.write_u64 = mem_cgroup_move_charge_write,
+	},
+	{
+		.name = "oom_control",
+		.read_map = mem_cgroup_oom_control_read,
+		.write_u64 = mem_cgroup_oom_control_write,
+		.register_event = mem_cgroup_oom_register_event,
+		.unregister_event = mem_cgroup_oom_unregister_event,
+		.private = MEMFILE_PRIVATE(_OOM_TYPE, OOM_CONTROL),
+	},
+#ifdef CONFIG_NUMA
+	{
+		.name = "numa_stat",
+		.open = mem_control_numa_stat_open,
+		.mode = S_IRUGO,
+	},
+#endif
+};
+
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
+static struct cftype memsw_cgroup_files[] = {
+	{
+		.name = "memsw.usage_in_bytes",
+		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE),
+		.read_u64 = mem_cgroup_read,
+		.register_event = mem_cgroup_usage_register_event,
+		.unregister_event = mem_cgroup_usage_unregister_event,
+	},
+	{
+		.name = "memsw.max_usage_in_bytes",
+		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE),
+		.trigger = mem_cgroup_reset,
+		.read_u64 = mem_cgroup_read,
+	},
+	{
+		.name = "memsw.limit_in_bytes",
+		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT),
+		.write_string = mem_cgroup_write,
+		.read_u64 = mem_cgroup_read,
+	},
+	{
+		.name = "memsw.failcnt",
+		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT),
+		.trigger = mem_cgroup_reset,
+		.read_u64 = mem_cgroup_read,
+	},
+};
+
+static int register_memsw_files(struct cgroup *cont, struct cgroup_subsys *ss)
+{
+	if (!do_swap_account)
+		return 0;
+	return cgroup_add_files(cont, ss, memsw_cgroup_files,
+				ARRAY_SIZE(memsw_cgroup_files));
+};
+#else
+static int register_memsw_files(struct cgroup *cont, struct cgroup_subsys *ss)
+{
+	return 0;
+}
+#endif
+
+static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
+{
+	struct mem_cgroup_per_node *pn;
+	struct mem_cgroup_per_zone *mz;
+	enum lru_list lru;
+	int zone, tmp = node;
+	/*
+	 * This routine is called against possible nodes.
+	 * But it's BUG to call kmalloc() against offline node.
+	 *
+	 * TODO: this routine can waste much memory for nodes which will
+	 *       never be onlined. It's better to use memory hotplug callback
+	 *       function.
+	 */
+	if (!node_state(node, N_NORMAL_MEMORY))
+		tmp = -1;
+	pn = kzalloc_node(sizeof(*pn), GFP_KERNEL, tmp);
+	if (!pn)
+		return 1;
+
+	for (zone = 0; zone < MAX_NR_ZONES; zone++) {
+		mz = &pn->zoneinfo[zone];
+		for_each_lru(lru)
+			INIT_LIST_HEAD(&mz->lruvec.lists[lru]);
+		mz->usage_in_excess = 0;
+		mz->on_tree = false;
+		mz->memcg = memcg;
+	}
+	memcg->info.nodeinfo[node] = pn;
+	return 0;
+}
+
+static void free_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
+{
+	kfree(memcg->info.nodeinfo[node]);
+}
+
+static struct mem_cgroup *mem_cgroup_alloc(void)
+{
+	struct mem_cgroup *memcg;
+	int size = sizeof(struct mem_cgroup);
+
+	/* Can be very big if MAX_NUMNODES is very big */
+	if (size < PAGE_SIZE)
+		memcg = kzalloc(size, GFP_KERNEL);
+	else
+		memcg = vzalloc(size);
+
+	if (!memcg)
+		return NULL;
+
+	memcg->stat = alloc_percpu(struct mem_cgroup_stat_cpu);
+	if (!memcg->stat)
+		goto out_free;
+	spin_lock_init(&memcg->pcp_counter_lock);
+	return memcg;
+
+out_free:
+	if (size < PAGE_SIZE)
+		kfree(memcg);
+	else
+		vfree(memcg);
+	return NULL;
+}
+
+/*
+ * Helpers for freeing a vzalloc()ed mem_cgroup by RCU,
+ * but in process context.  The work_freeing structure is overlaid
+ * on the rcu_freeing structure, which itself is overlaid on memsw.
+ */
+static void vfree_work(struct work_struct *work)
+{
+	struct mem_cgroup *memcg;
+
+	memcg = container_of(work, struct mem_cgroup, work_freeing);
+	vfree(memcg);
+}
+static void vfree_rcu(struct rcu_head *rcu_head)
+{
+	struct mem_cgroup *memcg;
+
+	memcg = container_of(rcu_head, struct mem_cgroup, rcu_freeing);
+	INIT_WORK(&memcg->work_freeing, vfree_work);
+	schedule_work(&memcg->work_freeing);
+}
+
+/*
+ * At destroying mem_cgroup, references from swap_cgroup can remain.
+ * (scanning all at force_empty is too costly...)
+ *
+ * Instead of clearing all references at force_empty, we remember
+ * the number of reference from swap_cgroup and free mem_cgroup when
+ * it goes down to 0.
+ *
+ * Removal of cgroup itself succeeds regardless of refs from swap.
+ */
+
+static void __mem_cgroup_free(struct mem_cgroup *memcg)
+{
+	int node;
+
+	mem_cgroup_remove_from_trees(memcg);
+	free_css_id(&mem_cgroup_subsys, &memcg->css);
+
+	for_each_node(node)
+		free_mem_cgroup_per_zone_info(memcg, node);
+
+	free_percpu(memcg->stat);
+	if (sizeof(struct mem_cgroup) < PAGE_SIZE)
+		kfree_rcu(memcg, rcu_freeing);
+	else
+		call_rcu(&memcg->rcu_freeing, vfree_rcu);
+}
+
+static void mem_cgroup_get(struct mem_cgroup *memcg)
+{
+	atomic_inc(&memcg->refcnt);
+}
+
+static void __mem_cgroup_put(struct mem_cgroup *memcg, int count)
+{
+	if (atomic_sub_and_test(count, &memcg->refcnt)) {
+		struct mem_cgroup *parent = parent_mem_cgroup(memcg);
+		__mem_cgroup_free(memcg);
+		if (parent)
+			mem_cgroup_put(parent);
+	}
+}
+
+static void mem_cgroup_put(struct mem_cgroup *memcg)
+{
+	__mem_cgroup_put(memcg, 1);
+}
+
+/*
+ * Returns the parent mem_cgroup in memcgroup hierarchy with hierarchy enabled.
+ */
+struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg)
+{
+	if (!memcg->res.parent)
+		return NULL;
+	return mem_cgroup_from_res_counter(memcg->res.parent, res);
+}
+EXPORT_SYMBOL(parent_mem_cgroup);
+
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
+static void __init enable_swap_cgroup(void)
+{
+	if (!mem_cgroup_disabled() && really_do_swap_account)
+		do_swap_account = 1;
+}
+#else
+static void __init enable_swap_cgroup(void)
+{
+}
+#endif
+
+static int mem_cgroup_soft_limit_tree_init(void)
+{
+	struct mem_cgroup_tree_per_node *rtpn;
+	struct mem_cgroup_tree_per_zone *rtpz;
+	int tmp, node, zone;
+
+	for_each_node(node) {
+		tmp = node;
+		if (!node_state(node, N_NORMAL_MEMORY))
+			tmp = -1;
+		rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL, tmp);
+		if (!rtpn)
+			goto err_cleanup;
+
+		soft_limit_tree.rb_tree_per_node[node] = rtpn;
+
+		for (zone = 0; zone < MAX_NR_ZONES; zone++) {
+			rtpz = &rtpn->rb_tree_per_zone[zone];
+			rtpz->rb_root = RB_ROOT;
+			spin_lock_init(&rtpz->lock);
+		}
+	}
+	return 0;
+
+err_cleanup:
+	for_each_node(node) {
+		if (!soft_limit_tree.rb_tree_per_node[node])
+			break;
+		kfree(soft_limit_tree.rb_tree_per_node[node]);
+		soft_limit_tree.rb_tree_per_node[node] = NULL;
+	}
+	return 1;
+
+}
+
+static struct cgroup_subsys_state * __ref
+mem_cgroup_create(struct cgroup *cont)
+{
+	struct mem_cgroup *memcg, *parent;
+	long error = -ENOMEM;
+	int node;
+
+	memcg = mem_cgroup_alloc();
+	if (!memcg)
+		return ERR_PTR(error);
+
+	for_each_node(node)
+		if (alloc_mem_cgroup_per_zone_info(memcg, node))
+			goto free_out;
+
+	/* root ? */
+	if (cont->parent == NULL) {
+		int cpu;
+		enable_swap_cgroup();
+		parent = NULL;
+		if (mem_cgroup_soft_limit_tree_init())
+			goto free_out;
+		root_mem_cgroup = memcg;
+		for_each_possible_cpu(cpu) {
+			struct memcg_stock_pcp *stock =
+						&per_cpu(memcg_stock, cpu);
+			INIT_WORK(&stock->work, drain_local_stock);
+		}
+		hotcpu_notifier(memcg_cpu_hotplug_callback, 0);
+	} else {
+		parent = mem_cgroup_from_cont(cont->parent);
+		memcg->use_hierarchy = parent->use_hierarchy;
+		memcg->oom_kill_disable = parent->oom_kill_disable;
+	}
+
+	if (parent && parent->use_hierarchy) {
+		res_counter_init(&memcg->res, &parent->res);
+		res_counter_init(&memcg->memsw, &parent->memsw);
+		/*
+		 * We increment refcnt of the parent to ensure that we can
+		 * safely access it on res_counter_charge/uncharge.
+		 * This refcnt will be decremented when freeing this
+		 * mem_cgroup(see mem_cgroup_put).
+		 */
+		mem_cgroup_get(parent);
+	} else {
+		res_counter_init(&memcg->res, NULL);
+		res_counter_init(&memcg->memsw, NULL);
+	}
+	memcg->last_scanned_node = MAX_NUMNODES;
+	INIT_LIST_HEAD(&memcg->oom_notify);
+
+	if (parent)
+		memcg->swappiness = mem_cgroup_swappiness(parent);
+	atomic_set(&memcg->refcnt, 1);
+	memcg->move_charge_at_immigrate = 0;
+	mutex_init(&memcg->thresholds_lock);
+	spin_lock_init(&memcg->move_lock);
+	return &memcg->css;
+free_out:
+	__mem_cgroup_free(memcg);
+	return ERR_PTR(error);
+}
+
+static int mem_cgroup_pre_destroy(struct cgroup *cont)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+
+	return mem_cgroup_force_empty(memcg, false);
+}
+
+static void mem_cgroup_destroy(struct cgroup *cont)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+
+	kmem_cgroup_destroy(cont);
+
+	mem_cgroup_put(memcg);
+}
+
+static int mem_cgroup_populate(struct cgroup_subsys *ss,
+				struct cgroup *cont)
+{
+	int ret;
+
+	ret = cgroup_add_files(cont, ss, mem_cgroup_files,
+				ARRAY_SIZE(mem_cgroup_files));
+
+	if (!ret)
+		ret = register_memsw_files(cont, ss);
+
+	if (!ret)
+		ret = register_kmem_files(cont, ss);
+
+	return ret;
+}
+
+#ifdef CONFIG_MMU
+/* Handlers for move charge at task migration. */
+#define PRECHARGE_COUNT_AT_ONCE	256
+static int mem_cgroup_do_precharge(unsigned long count)
+{
+	int ret = 0;
+	int batch_count = PRECHARGE_COUNT_AT_ONCE;
+	struct mem_cgroup *memcg = mc.to;
+
+	if (mem_cgroup_is_root(memcg)) {
+		mc.precharge += count;
+		/* we don't need css_get for root */
+		return ret;
+	}
+	/* try to charge at once */
+	if (count > 1) {
+		struct res_counter *dummy;
+		/*
+		 * "memcg" cannot be under rmdir() because we've already checked
+		 * by cgroup_lock_live_cgroup() that it is not removed and we
+		 * are still under the same cgroup_mutex. So we can postpone
+		 * css_get().
+		 */
+		if (res_counter_charge(&memcg->res, PAGE_SIZE * count, &dummy))
+			goto one_by_one;
+		if (do_swap_account && res_counter_charge(&memcg->memsw,
+						PAGE_SIZE * count, &dummy)) {
+			res_counter_uncharge(&memcg->res, PAGE_SIZE * count);
+			goto one_by_one;
+		}
+		mc.precharge += count;
+		return ret;
+	}
+one_by_one:
+	/* fall back to one by one charge */
+	while (count--) {
+		if (signal_pending(current)) {
+			ret = -EINTR;
+			break;
+		}
+		if (!batch_count--) {
+			batch_count = PRECHARGE_COUNT_AT_ONCE;
+			cond_resched();
+		}
+		ret = __mem_cgroup_try_charge(NULL,
+					GFP_KERNEL, 1, &memcg, false);
+		if (ret)
+			/* mem_cgroup_clear_mc() will do uncharge later */
+			return ret;
+		mc.precharge++;
+	}
+	return ret;
+}
+
+/**
+ * get_mctgt_type - get target type of moving charge
+ * @vma: the vma the pte to be checked belongs
+ * @addr: the address corresponding to the pte to be checked
+ * @ptent: the pte to be checked
+ * @target: the pointer the target page or swap ent will be stored(can be NULL)
+ *
+ * Returns
+ *   0(MC_TARGET_NONE): if the pte is not a target for move charge.
+ *   1(MC_TARGET_PAGE): if the page corresponding to this pte is a target for
+ *     move charge. if @target is not NULL, the page is stored in target->page
+ *     with extra refcnt got(Callers should handle it).
+ *   2(MC_TARGET_SWAP): if the swap entry corresponding to this pte is a
+ *     target for charge migration. if @target is not NULL, the entry is stored
+ *     in target->ent.
+ *
+ * Called with pte lock held.
+ */
+union mc_target {
+	struct page	*page;
+	swp_entry_t	ent;
+};
+
+enum mc_target_type {
+	MC_TARGET_NONE = 0,
+	MC_TARGET_PAGE,
+	MC_TARGET_SWAP,
+};
+
+static struct page *mc_handle_present_pte(struct vm_area_struct *vma,
+						unsigned long addr, pte_t ptent)
+{
+	struct page *page = vm_normal_page(vma, addr, ptent);
+
+	if (!page || !page_mapped(page))
+		return NULL;
+	if (PageAnon(page)) {
+		/* we don't move shared anon */
+		if (!move_anon() || page_mapcount(page) > 2)
+			return NULL;
+	} else if (!move_file())
+		/* we ignore mapcount for file pages */
+		return NULL;
+	if (!get_page_unless_zero(page))
+		return NULL;
+
+	return page;
+}
+
+static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
+			unsigned long addr, pte_t ptent, swp_entry_t *entry)
+{
+	int usage_count;
+	struct page *page = NULL;
+	swp_entry_t ent = pte_to_swp_entry(ptent);
+
+	if (!move_anon() || non_swap_entry(ent))
+		return NULL;
+	usage_count = mem_cgroup_count_swap_user(ent, &page);
+	if (usage_count > 1) { /* we don't move shared anon */
+		if (page)
+			put_page(page);
+		return NULL;
+	}
+	if (do_swap_account)
+		entry->val = ent.val;
+
+	return page;
+}
+
+static struct page *mc_handle_file_pte(struct vm_area_struct *vma,
+			unsigned long addr, pte_t ptent, swp_entry_t *entry)
+{
+	struct page *page = NULL;
+	struct inode *inode;
+	struct address_space *mapping;
+	pgoff_t pgoff;
+
+	if (!vma->vm_file) /* anonymous vma */
+		return NULL;
+	if (!move_file())
+		return NULL;
+
+	inode = vma->vm_file->f_path.dentry->d_inode;
+	mapping = vma->vm_file->f_mapping;
+	if (pte_none(ptent))
+		pgoff = linear_page_index(vma, addr);
+	else /* pte_file(ptent) is true */
+		pgoff = pte_to_pgoff(ptent);
+
+	/* page is moved even if it's not RSS of this task(page-faulted). */
+	page = find_get_page(mapping, pgoff);
+
+#ifdef CONFIG_SWAP
+	/* shmem/tmpfs may report page out on swap: account for that too. */
+	if (radix_tree_exceptional_entry(page)) {
+		swp_entry_t swap = radix_to_swp_entry(page);
+		if (do_swap_account)
+			*entry = swap;
+		page = find_get_page(&swapper_space, swap.val);
+	}
+#endif
+	return page;
+}
+
+static enum mc_target_type get_mctgt_type(struct vm_area_struct *vma,
+		unsigned long addr, pte_t ptent, union mc_target *target)
+{
+	struct page *page = NULL;
+	struct page_cgroup *pc;
+	enum mc_target_type ret = MC_TARGET_NONE;
+	swp_entry_t ent = { .val = 0 };
+
+	if (pte_present(ptent))
+		page = mc_handle_present_pte(vma, addr, ptent);
+	else if (is_swap_pte(ptent))
+		page = mc_handle_swap_pte(vma, addr, ptent, &ent);
+	else if (pte_none(ptent) || pte_file(ptent))
+		page = mc_handle_file_pte(vma, addr, ptent, &ent);
+
+	if (!page && !ent.val)
+		return ret;
+	if (page) {
+		pc = lookup_page_cgroup(page);
+		/*
+		 * Do only loose check w/o page_cgroup lock.
+		 * mem_cgroup_move_account() checks the pc is valid or not under
+		 * the lock.
+		 */
+		if (PageCgroupUsed(pc) && pc->mem_cgroup == mc.from) {
+			ret = MC_TARGET_PAGE;
+			if (target)
+				target->page = page;
+		}
+		if (!ret || !target)
+			put_page(page);
+	}
+	/* There is a swap entry and a page doesn't exist or isn't charged */
+	if (ent.val && !ret &&
+			css_id(&mc.from->css) == lookup_swap_cgroup_id(ent)) {
+		ret = MC_TARGET_SWAP;
+		if (target)
+			target->ent = ent;
+	}
+	return ret;
+}
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+/*
+ * We don't consider swapping or file mapped pages because THP does not
+ * support them for now.
+ * Caller should make sure that pmd_trans_huge(pmd) is true.
+ */
+static enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma,
+		unsigned long addr, pmd_t pmd, union mc_target *target)
+{
+	struct page *page = NULL;
+	struct page_cgroup *pc;
+	enum mc_target_type ret = MC_TARGET_NONE;
+
+	page = pmd_page(pmd);
+	VM_BUG_ON(!page || !PageHead(page));
+	if (!move_anon())
+		return ret;
+	pc = lookup_page_cgroup(page);
+	if (PageCgroupUsed(pc) && pc->mem_cgroup == mc.from) {
+		ret = MC_TARGET_PAGE;
+		if (target) {
+			get_page(page);
+			target->page = page;
+		}
+	}
+	return ret;
+}
+#else
+static inline enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma,
+		unsigned long addr, pmd_t pmd, union mc_target *target)
+{
+	return MC_TARGET_NONE;
+}
+#endif
+
+static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd,
+					unsigned long addr, unsigned long end,
+					struct mm_walk *walk)
+{
+	struct vm_area_struct *vma = walk->private;
+	pte_t *pte;
+	spinlock_t *ptl;
+
+	if (pmd_trans_huge_lock(pmd, vma) == 1) {
+		if (get_mctgt_type_thp(vma, addr, *pmd, NULL) == MC_TARGET_PAGE)
+			mc.precharge += HPAGE_PMD_NR;
+		spin_unlock(&vma->vm_mm->page_table_lock);
+		return 0;
+	}
+
+	if (pmd_trans_unstable(pmd))
+		return 0;
+	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
+	for (; addr != end; pte++, addr += PAGE_SIZE)
+		if (get_mctgt_type(vma, addr, *pte, NULL))
+			mc.precharge++;	/* increment precharge temporarily */
+	pte_unmap_unlock(pte - 1, ptl);
+	cond_resched();
+
+	return 0;
+}
+
+static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
+{
+	unsigned long precharge;
+	struct vm_area_struct *vma;
+
+	down_read(&mm->mmap_sem);
+	for (vma = mm->mmap; vma; vma = vma->vm_next) {
+		struct mm_walk mem_cgroup_count_precharge_walk = {
+			.pmd_entry = mem_cgroup_count_precharge_pte_range,
+			.mm = mm,
+			.private = vma,
+		};
+		if (is_vm_hugetlb_page(vma))
+			continue;
+		walk_page_range(vma->vm_start, vma->vm_end,
+					&mem_cgroup_count_precharge_walk);
+	}
+	up_read(&mm->mmap_sem);
+
+	precharge = mc.precharge;
+	mc.precharge = 0;
+
+	return precharge;
+}
+
+static int mem_cgroup_precharge_mc(struct mm_struct *mm)
+{
+	unsigned long precharge = mem_cgroup_count_precharge(mm);
+
+	VM_BUG_ON(mc.moving_task);
+	mc.moving_task = current;
+	return mem_cgroup_do_precharge(precharge);
+}
+
+/* cancels all extra charges on mc.from and mc.to, and wakes up all waiters. */
+static void __mem_cgroup_clear_mc(void)
+{
+	struct mem_cgroup *from = mc.from;
+	struct mem_cgroup *to = mc.to;
+
+	/* we must uncharge all the leftover precharges from mc.to */
+	if (mc.precharge) {
+		__mem_cgroup_cancel_charge(mc.to, mc.precharge);
+		mc.precharge = 0;
+	}
+	/*
+	 * we didn't uncharge from mc.from at mem_cgroup_move_account(), so
+	 * we must uncharge here.
+	 */
+	if (mc.moved_charge) {
+		__mem_cgroup_cancel_charge(mc.from, mc.moved_charge);
+		mc.moved_charge = 0;
+	}
+	/* we must fixup refcnts and charges */
+	if (mc.moved_swap) {
+		/* uncharge swap account from the old cgroup */
+		if (!mem_cgroup_is_root(mc.from))
+			res_counter_uncharge(&mc.from->memsw,
+						PAGE_SIZE * mc.moved_swap);
+		__mem_cgroup_put(mc.from, mc.moved_swap);
+
+		if (!mem_cgroup_is_root(mc.to)) {
+			/*
+			 * we charged both to->res and to->memsw, so we should
+			 * uncharge to->res.
+			 */
+			res_counter_uncharge(&mc.to->res,
+						PAGE_SIZE * mc.moved_swap);
+		}
+		/* we've already done mem_cgroup_get(mc.to) */
+		mc.moved_swap = 0;
+	}
+	memcg_oom_recover(from);
+	memcg_oom_recover(to);
+	wake_up_all(&mc.waitq);
+}
+
+static void mem_cgroup_clear_mc(void)
+{
+	struct mem_cgroup *from = mc.from;
+
+	/*
+	 * we must clear moving_task before waking up waiters at the end of
+	 * task migration.
+	 */
+	mc.moving_task = NULL;
+	__mem_cgroup_clear_mc();
+	spin_lock(&mc.lock);
+	mc.from = NULL;
+	mc.to = NULL;
+	spin_unlock(&mc.lock);
+	mem_cgroup_end_move(from);
+}
+
+static int mem_cgroup_can_attach(struct cgroup *cgroup,
+				 struct cgroup_taskset *tset)
+{
+	struct task_struct *p = cgroup_taskset_first(tset);
+	int ret = 0;
+	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgroup);
+
+	if (memcg->move_charge_at_immigrate) {
+		struct mm_struct *mm;
+		struct mem_cgroup *from = mem_cgroup_from_task(p);
+
+		VM_BUG_ON(from == memcg);
+
+		mm = get_task_mm(p);
+		if (!mm)
+			return 0;
+		/* We move charges only when we move a owner of the mm */
+		if (mm->owner == p) {
+			VM_BUG_ON(mc.from);
+			VM_BUG_ON(mc.to);
+			VM_BUG_ON(mc.precharge);
+			VM_BUG_ON(mc.moved_charge);
+			VM_BUG_ON(mc.moved_swap);
+			mem_cgroup_start_move(from);
+			spin_lock(&mc.lock);
+			mc.from = from;
+			mc.to = memcg;
+			spin_unlock(&mc.lock);
+			/* We set mc.moving_task later */
+
+			ret = mem_cgroup_precharge_mc(mm);
+			if (ret)
+				mem_cgroup_clear_mc();
+		}
+		mmput(mm);
+	}
+	return ret;
+}
+
+static void mem_cgroup_cancel_attach(struct cgroup *cgroup,
+				     struct cgroup_taskset *tset)
+{
+	mem_cgroup_clear_mc();
+}
+
+static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,
+				unsigned long addr, unsigned long end,
+				struct mm_walk *walk)
+{
+	int ret = 0;
+	struct vm_area_struct *vma = walk->private;
+	pte_t *pte;
+	spinlock_t *ptl;
+	enum mc_target_type target_type;
+	union mc_target target;
+	struct page *page;
+	struct page_cgroup *pc;
+
+	/*
+	 * We don't take compound_lock() here but no race with splitting thp
+	 * happens because:
+	 *  - if pmd_trans_huge_lock() returns 1, the relevant thp is not
+	 *    under splitting, which means there's no concurrent thp split,
+	 *  - if another thread runs into split_huge_page() just after we
+	 *    entered this if-block, the thread must wait for page table lock
+	 *    to be unlocked in __split_huge_page_splitting(), where the main
+	 *    part of thp split is not executed yet.
+	 */
+	if (pmd_trans_huge_lock(pmd, vma) == 1) {
+		if (mc.precharge < HPAGE_PMD_NR) {
+			spin_unlock(&vma->vm_mm->page_table_lock);
+			return 0;
+		}
+		target_type = get_mctgt_type_thp(vma, addr, *pmd, &target);
+		if (target_type == MC_TARGET_PAGE) {
+			page = target.page;
+			if (!isolate_lru_page(page)) {
+				pc = lookup_page_cgroup(page);
+				if (!mem_cgroup_move_account(page, HPAGE_PMD_NR,
+							     pc, mc.from, mc.to,
+							     false)) {
+					mc.precharge -= HPAGE_PMD_NR;
+					mc.moved_charge += HPAGE_PMD_NR;
+				}
+				putback_lru_page(page);
+			}
+			put_page(page);
+		}
+		spin_unlock(&vma->vm_mm->page_table_lock);
+		return 0;
+	}
+
+	if (pmd_trans_unstable(pmd))
+		return 0;
+retry:
+	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
+	for (; addr != end; addr += PAGE_SIZE) {
+		pte_t ptent = *(pte++);
+		swp_entry_t ent;
+
+		if (!mc.precharge)
+			break;
+
+		switch (get_mctgt_type(vma, addr, ptent, &target)) {
+		case MC_TARGET_PAGE:
+			page = target.page;
+			if (isolate_lru_page(page))
+				goto put;
+			pc = lookup_page_cgroup(page);
+			if (!mem_cgroup_move_account(page, 1, pc,
+						     mc.from, mc.to, false)) {
+				mc.precharge--;
+				/* we uncharge from mc.from later. */
+				mc.moved_charge++;
+			}
+			putback_lru_page(page);
+put:			/* get_mctgt_type() gets the page */
+			put_page(page);
+			break;
+		case MC_TARGET_SWAP:
+			ent = target.ent;
+			if (!mem_cgroup_move_swap_account(ent,
+						mc.from, mc.to, false)) {
+				mc.precharge--;
+				/* we fixup refcnts and charges later. */
+				mc.moved_swap++;
+			}
+			break;
+		default:
+			break;
+		}
+	}
+	pte_unmap_unlock(pte - 1, ptl);
+	cond_resched();
+
+	if (addr != end) {
+		/*
+		 * We have consumed all precharges we got in can_attach().
+		 * We try charge one by one, but don't do any additional
+		 * charges to mc.to if we have failed in charge once in attach()
+		 * phase.
+		 */
+		ret = mem_cgroup_do_precharge(1);
+		if (!ret)
+			goto retry;
+	}
+
+	return ret;
+}
+
+static void mem_cgroup_move_charge(struct mm_struct *mm)
+{
+	struct vm_area_struct *vma;
+
+	lru_add_drain_all();
+retry:
+	if (unlikely(!down_read_trylock(&mm->mmap_sem))) {
+		/*
+		 * Someone who are holding the mmap_sem might be waiting in
+		 * waitq. So we cancel all extra charges, wake up all waiters,
+		 * and retry. Because we cancel precharges, we might not be able
+		 * to move enough charges, but moving charge is a best-effort
+		 * feature anyway, so it wouldn't be a big problem.
+		 */
+		__mem_cgroup_clear_mc();
+		cond_resched();
+		goto retry;
+	}
+	for (vma = mm->mmap; vma; vma = vma->vm_next) {
+		int ret;
+		struct mm_walk mem_cgroup_move_charge_walk = {
+			.pmd_entry = mem_cgroup_move_charge_pte_range,
+			.mm = mm,
+			.private = vma,
+		};
+		if (is_vm_hugetlb_page(vma))
+			continue;
+		ret = walk_page_range(vma->vm_start, vma->vm_end,
+						&mem_cgroup_move_charge_walk);
+		if (ret)
+			/*
+			 * means we have consumed all precharges and failed in
+			 * doing additional charge. Just abandon here.
+			 */
+			break;
+	}
+	up_read(&mm->mmap_sem);
+}
+
+static void mem_cgroup_move_task(struct cgroup *cont,
+				 struct cgroup_taskset *tset)
+{
+	struct task_struct *p = cgroup_taskset_first(tset);
+	struct mm_struct *mm = get_task_mm(p);
+
+	if (mm) {
+		if (mc.to)
+			mem_cgroup_move_charge(mm);
+		put_swap_token(mm);
+		mmput(mm);
+	}
+	if (mc.to)
+		mem_cgroup_clear_mc();
+}
+#else	/* !CONFIG_MMU */
+static int mem_cgroup_can_attach(struct cgroup *cgroup,
+				 struct cgroup_taskset *tset)
+{
+	return 0;
+}
+static void mem_cgroup_cancel_attach(struct cgroup *cgroup,
+				     struct cgroup_taskset *tset)
+{
+}
+static void mem_cgroup_move_task(struct cgroup *cont,
+				 struct cgroup_taskset *tset)
+{
+}
+#endif
+
+struct cgroup_subsys mem_cgroup_subsys = {
+	.name = "memory",
+	.subsys_id = mem_cgroup_subsys_id,
+	.create = mem_cgroup_create,
+	.pre_destroy = mem_cgroup_pre_destroy,
+	.destroy = mem_cgroup_destroy,
+	.populate = mem_cgroup_populate,
+	.can_attach = mem_cgroup_can_attach,
+	.cancel_attach = mem_cgroup_cancel_attach,
+	.attach = mem_cgroup_move_task,
+	.early_init = 0,
+	.use_id = 1,
+};
+
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
+static int __init enable_swap_account(char *s)
+{
+	/* consider enabled if no parameter or 1 is given */
+	if (!strcmp(s, "1"))
+		really_do_swap_account = 1;
+	else if (!strcmp(s, "0"))
+		really_do_swap_account = 0;
+	return 1;
+}
+__setup("swapaccount=", enable_swap_account);
+
+#endif