Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 6784 insertions, 0 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
new file mode 100644
index 000000000..f3aa6e621
--- /dev/null
+++ b/mm/memcontrol.c
@@ -0,0 +1,6784 @@
+/* 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
+ *
+ * Kernel Memory Controller
+ * Copyright (C) 2012 Parallels Inc. and Google Inc.
+ * Authors: Glauber Costa and Suleiman Souhlal
+ *
+ * Native page reclaim
+ * Charge lifetime sanitation
+ * Lockless page tracking & accounting
+ * Unified hierarchy configuration model
+ * Copyright (C) 2015 Red Hat, Inc., Johannes Weiner
+ *
+ * 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/page_counter.h>
+#include <linux/memcontrol.h>
+#include <linux/cgroup.h>
+#include <linux/mm.h>
+#include <linux/sched/mm.h>
+#include <linux/shmem_fs.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/poll.h>
+#include <linux/sort.h>
+#include <linux/fs.h>
+#include <linux/seq_file.h>
+#include <linux/vmpressure.h>
+#include <linux/mm_inline.h>
+#include <linux/swap_cgroup.h>
+#include <linux/cpu.h>
+#include <linux/oom.h>
+#include <linux/lockdep.h>
+#include <linux/file.h>
+#include <linux/tracehook.h>
+#include "internal.h"
+#include <net/sock.h>
+#include <net/ip.h>
+#include "slab.h"
+
+#include <linux/uaccess.h>
+
+#include <trace/events/vmscan.h>
+
+struct cgroup_subsys memory_cgrp_subsys __read_mostly;
+EXPORT_SYMBOL(memory_cgrp_subsys);
+
+struct mem_cgroup *root_mem_cgroup __read_mostly;
+
+#define MEM_CGROUP_RECLAIM_RETRIES	5
+
+/* Socket memory accounting disabled? */
+static bool cgroup_memory_nosocket;
+
+/* Kernel memory accounting disabled? */
+static bool cgroup_memory_nokmem;
+
+/* Whether the swap controller is active */
+#ifdef CONFIG_MEMCG_SWAP
+int do_swap_account __read_mostly;
+#else
+#define do_swap_account		0
+#endif
+
+/* Whether legacy memory+swap accounting is active */
+static bool do_memsw_account(void)
+{
+	return !cgroup_subsys_on_dfl(memory_cgrp_subsys) && do_swap_account;
+}
+
+static const char *const mem_cgroup_lru_names[] = {
+	"inactive_anon",
+	"active_anon",
+	"inactive_file",
+	"active_file",
+	"unevictable",
+};
+
+#define THRESHOLDS_EVENTS_TARGET 128
+#define SOFTLIMIT_EVENTS_TARGET 1024
+#define NUMAINFO_EVENTS_TARGET	1024
+
+/*
+ * Cgroups above their limits are maintained in a RB-Tree, independent of
+ * their hierarchy representation
+ */
+
+struct mem_cgroup_tree_per_node {
+	struct rb_root rb_root;
+	struct rb_node *rb_rightmost;
+	spinlock_t lock;
+};
+
+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;
+
+/* for OOM */
+struct mem_cgroup_eventfd_list {
+	struct list_head list;
+	struct eventfd_ctx *eventfd;
+};
+
+/*
+ * cgroup_event represents events which userspace want to receive.
+ */
+struct mem_cgroup_event {
+	/*
+	 * memcg which the event belongs to.
+	 */
+	struct mem_cgroup *memcg;
+	/*
+	 * eventfd to signal userspace about the event.
+	 */
+	struct eventfd_ctx *eventfd;
+	/*
+	 * Each of these stored in a list by the cgroup.
+	 */
+	struct list_head list;
+	/*
+	 * register_event() callback will be used to add new userspace
+	 * waiter for changes related to this event.  Use eventfd_signal()
+	 * on eventfd to send notification to userspace.
+	 */
+	int (*register_event)(struct mem_cgroup *memcg,
+			      struct eventfd_ctx *eventfd, const char *args);
+	/*
+	 * unregister_event() callback will be called when userspace closes
+	 * the eventfd or on cgroup removing.  This callback must be set,
+	 * if you want provide notification functionality.
+	 */
+	void (*unregister_event)(struct mem_cgroup *memcg,
+				 struct eventfd_ctx *eventfd);
+	/*
+	 * All fields below needed to unregister event when
+	 * userspace closes eventfd.
+	 */
+	poll_table pt;
+	wait_queue_head_t *wqh;
+	wait_queue_entry_t wait;
+	struct work_struct remove;
+};
+
+static void mem_cgroup_threshold(struct mem_cgroup *memcg);
+static void mem_cgroup_oom_notify(struct mem_cgroup *memcg);
+
+/* Stuffs for move charges at task migration. */
+/*
+ * Types of charges to be moved.
+ */
+#define MOVE_ANON	0x1U
+#define MOVE_FILE	0x2U
+#define MOVE_MASK	(MOVE_ANON | MOVE_FILE)
+
+/* "mc" and its members are protected by cgroup_mutex */
+static struct move_charge_struct {
+	spinlock_t	  lock; /* for from, to */
+	struct mm_struct  *mm;
+	struct mem_cgroup *from;
+	struct mem_cgroup *to;
+	unsigned long flags;
+	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),
+};
+
+/*
+ * 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_ANON,
+	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 */
+enum res_type {
+	_MEM,
+	_MEMSWAP,
+	_OOM_TYPE,
+	_KMEM,
+	_TCP,
+};
+
+#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)
+
+/*
+ * 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 should_force_charge(void)
+{
+	return tsk_is_oom_victim(current) || fatal_signal_pending(current) ||
+		(current->flags & PF_EXITING);
+}
+
+/* Some nice accessors for the vmpressure. */
+struct vmpressure *memcg_to_vmpressure(struct mem_cgroup *memcg)
+{
+	if (!memcg)
+		memcg = root_mem_cgroup;
+	return &memcg->vmpressure;
+}
+
+struct cgroup_subsys_state *vmpressure_to_css(struct vmpressure *vmpr)
+{
+	return &container_of(vmpr, struct mem_cgroup, vmpressure)->css;
+}
+
+#ifdef CONFIG_MEMCG_KMEM
+/*
+ * This will be the memcg's index in each cache's ->memcg_params.memcg_caches.
+ * The main reason for not using cgroup id for this:
+ *  this works better in sparse environments, where we have a lot of memcgs,
+ *  but only a few kmem-limited. Or also, if we have, for instance, 200
+ *  memcgs, and none but the 200th is kmem-limited, we'd have to have a
+ *  200 entry array for that.
+ *
+ * The current size of the caches array is stored in memcg_nr_cache_ids. It
+ * will double each time we have to increase it.
+ */
+static DEFINE_IDA(memcg_cache_ida);
+int memcg_nr_cache_ids;
+
+/* Protects memcg_nr_cache_ids */
+static DECLARE_RWSEM(memcg_cache_ids_sem);
+
+void memcg_get_cache_ids(void)
+{
+	down_read(&memcg_cache_ids_sem);
+}
+
+void memcg_put_cache_ids(void)
+{
+	up_read(&memcg_cache_ids_sem);
+}
+
+/*
+ * MIN_SIZE is different than 1, because we would like to avoid going through
+ * the alloc/free process all the time. In a small machine, 4 kmem-limited
+ * cgroups is a reasonable guess. In the future, it could be a parameter or
+ * tunable, but that is strictly not necessary.
+ *
+ * MAX_SIZE should be as large as the number of cgrp_ids. Ideally, we could get
+ * this constant directly from cgroup, but it is understandable that this is
+ * better kept as an internal representation in cgroup.c. In any case, the
+ * cgrp_id space is not getting any smaller, and we don't have to necessarily
+ * increase ours as well if it increases.
+ */
+#define MEMCG_CACHES_MIN_SIZE 4
+#define MEMCG_CACHES_MAX_SIZE MEM_CGROUP_ID_MAX
+
+/*
+ * A lot of the calls to the cache allocation functions are expected to be
+ * inlined by the compiler. Since the calls to memcg_kmem_get_cache are
+ * conditional to this static branch, we'll have to allow modules that does
+ * kmem_cache_alloc and the such to see this symbol as well
+ */
+DEFINE_STATIC_KEY_FALSE(memcg_kmem_enabled_key);
+EXPORT_SYMBOL(memcg_kmem_enabled_key);
+
+struct workqueue_struct *memcg_kmem_cache_wq;
+
+static int memcg_shrinker_map_size;
+static DEFINE_MUTEX(memcg_shrinker_map_mutex);
+
+static void memcg_free_shrinker_map_rcu(struct rcu_head *head)
+{
+	kvfree(container_of(head, struct memcg_shrinker_map, rcu));
+}
+
+static int memcg_expand_one_shrinker_map(struct mem_cgroup *memcg,
+					 int size, int old_size)
+{
+	struct memcg_shrinker_map *new, *old;
+	int nid;
+
+	lockdep_assert_held(&memcg_shrinker_map_mutex);
+
+	for_each_node(nid) {
+		old = rcu_dereference_protected(
+			mem_cgroup_nodeinfo(memcg, nid)->shrinker_map, true);
+		/* Not yet online memcg */
+		if (!old)
+			return 0;
+
+		new = kvmalloc(sizeof(*new) + size, GFP_KERNEL);
+		if (!new)
+			return -ENOMEM;
+
+		/* Set all old bits, clear all new bits */
+		memset(new->map, (int)0xff, old_size);
+		memset((void *)new->map + old_size, 0, size - old_size);
+
+		rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_map, new);
+		call_rcu(&old->rcu, memcg_free_shrinker_map_rcu);
+	}
+
+	return 0;
+}
+
+static void memcg_free_shrinker_maps(struct mem_cgroup *memcg)
+{
+	struct mem_cgroup_per_node *pn;
+	struct memcg_shrinker_map *map;
+	int nid;
+
+	if (mem_cgroup_is_root(memcg))
+		return;
+
+	for_each_node(nid) {
+		pn = mem_cgroup_nodeinfo(memcg, nid);
+		map = rcu_dereference_protected(pn->shrinker_map, true);
+		if (map)
+			kvfree(map);
+		rcu_assign_pointer(pn->shrinker_map, NULL);
+	}
+}
+
+static int memcg_alloc_shrinker_maps(struct mem_cgroup *memcg)
+{
+	struct memcg_shrinker_map *map;
+	int nid, size, ret = 0;
+
+	if (mem_cgroup_is_root(memcg))
+		return 0;
+
+	mutex_lock(&memcg_shrinker_map_mutex);
+	size = memcg_shrinker_map_size;
+	for_each_node(nid) {
+		map = kvzalloc(sizeof(*map) + size, GFP_KERNEL);
+		if (!map) {
+			memcg_free_shrinker_maps(memcg);
+			ret = -ENOMEM;
+			break;
+		}
+		rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_map, map);
+	}
+	mutex_unlock(&memcg_shrinker_map_mutex);
+
+	return ret;
+}
+
+int memcg_expand_shrinker_maps(int new_id)
+{
+	int size, old_size, ret = 0;
+	struct mem_cgroup *memcg;
+
+	size = DIV_ROUND_UP(new_id + 1, BITS_PER_LONG) * sizeof(unsigned long);
+	old_size = memcg_shrinker_map_size;
+	if (size <= old_size)
+		return 0;
+
+	mutex_lock(&memcg_shrinker_map_mutex);
+	if (!root_mem_cgroup)
+		goto unlock;
+
+	for_each_mem_cgroup(memcg) {
+		if (mem_cgroup_is_root(memcg))
+			continue;
+		ret = memcg_expand_one_shrinker_map(memcg, size, old_size);
+		if (ret) {
+			mem_cgroup_iter_break(NULL, memcg);
+			goto unlock;
+		}
+	}
+unlock:
+	if (!ret)
+		memcg_shrinker_map_size = size;
+	mutex_unlock(&memcg_shrinker_map_mutex);
+	return ret;
+}
+
+void memcg_set_shrinker_bit(struct mem_cgroup *memcg, int nid, int shrinker_id)
+{
+	if (shrinker_id >= 0 && memcg && !mem_cgroup_is_root(memcg)) {
+		struct memcg_shrinker_map *map;
+
+		rcu_read_lock();
+		map = rcu_dereference(memcg->nodeinfo[nid]->shrinker_map);
+		/* Pairs with smp mb in shrink_slab() */
+		smp_mb__before_atomic();
+		set_bit(shrinker_id, map->map);
+		rcu_read_unlock();
+	}
+}
+
+#else /* CONFIG_MEMCG_KMEM */
+static int memcg_alloc_shrinker_maps(struct mem_cgroup *memcg)
+{
+	return 0;
+}
+static void memcg_free_shrinker_maps(struct mem_cgroup *memcg) { }
+#endif /* CONFIG_MEMCG_KMEM */
+
+/**
+ * mem_cgroup_css_from_page - css of the memcg associated with a page
+ * @page: page of interest
+ *
+ * If memcg is bound to the default hierarchy, css of the memcg associated
+ * with @page is returned.  The returned css remains associated with @page
+ * until it is released.
+ *
+ * If memcg is bound to a traditional hierarchy, the css of root_mem_cgroup
+ * is returned.
+ */
+struct cgroup_subsys_state *mem_cgroup_css_from_page(struct page *page)
+{
+	struct mem_cgroup *memcg;
+
+	memcg = page->mem_cgroup;
+
+	if (!memcg || !cgroup_subsys_on_dfl(memory_cgrp_subsys))
+		memcg = root_mem_cgroup;
+
+	return &memcg->css;
+}
+
+/**
+ * page_cgroup_ino - return inode number of the memcg a page is charged to
+ * @page: the page
+ *
+ * Look up the closest online ancestor of the memory cgroup @page is charged to
+ * and return its inode number or 0 if @page is not charged to any cgroup. It
+ * is safe to call this function without holding a reference to @page.
+ *
+ * Note, this function is inherently racy, because there is nothing to prevent
+ * the cgroup inode from getting torn down and potentially reallocated a moment
+ * after page_cgroup_ino() returns, so it only should be used by callers that
+ * do not care (such as procfs interfaces).
+ */
+ino_t page_cgroup_ino(struct page *page)
+{
+	struct mem_cgroup *memcg;
+	unsigned long ino = 0;
+
+	rcu_read_lock();
+	memcg = READ_ONCE(page->mem_cgroup);
+	while (memcg && !(memcg->css.flags & CSS_ONLINE))
+		memcg = parent_mem_cgroup(memcg);
+	if (memcg)
+		ino = cgroup_ino(memcg->css.cgroup);
+	rcu_read_unlock();
+	return ino;
+}
+
+static struct mem_cgroup_per_node *
+mem_cgroup_page_nodeinfo(struct mem_cgroup *memcg, struct page *page)
+{
+	int nid = page_to_nid(page);
+
+	return memcg->nodeinfo[nid];
+}
+
+static struct mem_cgroup_tree_per_node *
+soft_limit_tree_node(int nid)
+{
+	return soft_limit_tree.rb_tree_per_node[nid];
+}
+
+static struct mem_cgroup_tree_per_node *
+soft_limit_tree_from_page(struct page *page)
+{
+	int nid = page_to_nid(page);
+
+	return soft_limit_tree.rb_tree_per_node[nid];
+}
+
+static void __mem_cgroup_insert_exceeded(struct mem_cgroup_per_node *mz,
+					 struct mem_cgroup_tree_per_node *mctz,
+					 unsigned long new_usage_in_excess)
+{
+	struct rb_node **p = &mctz->rb_root.rb_node;
+	struct rb_node *parent = NULL;
+	struct mem_cgroup_per_node *mz_node;
+	bool rightmost = true;
+
+	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_node,
+					tree_node);
+		if (mz->usage_in_excess < mz_node->usage_in_excess) {
+			p = &(*p)->rb_left;
+			rightmost = false;
+		}
+
+		/*
+		 * 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;
+	}
+
+	if (rightmost)
+		mctz->rb_rightmost = &mz->tree_node;
+
+	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_per_node *mz,
+					 struct mem_cgroup_tree_per_node *mctz)
+{
+	if (!mz->on_tree)
+		return;
+
+	if (&mz->tree_node == mctz->rb_rightmost)
+		mctz->rb_rightmost = rb_prev(&mz->tree_node);
+
+	rb_erase(&mz->tree_node, &mctz->rb_root);
+	mz->on_tree = false;
+}
+
+static void mem_cgroup_remove_exceeded(struct mem_cgroup_per_node *mz,
+				       struct mem_cgroup_tree_per_node *mctz)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&mctz->lock, flags);
+	__mem_cgroup_remove_exceeded(mz, mctz);
+	spin_unlock_irqrestore(&mctz->lock, flags);
+}
+
+static unsigned long soft_limit_excess(struct mem_cgroup *memcg)
+{
+	unsigned long nr_pages = page_counter_read(&memcg->memory);
+	unsigned long soft_limit = READ_ONCE(memcg->soft_limit);
+	unsigned long excess = 0;
+
+	if (nr_pages > soft_limit)
+		excess = nr_pages - soft_limit;
+
+	return excess;
+}
+
+static void mem_cgroup_update_tree(struct mem_cgroup *memcg, struct page *page)
+{
+	unsigned long excess;
+	struct mem_cgroup_per_node *mz;
+	struct mem_cgroup_tree_per_node *mctz;
+
+	mctz = soft_limit_tree_from_page(page);
+	if (!mctz)
+		return;
+	/*
+	 * 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_page_nodeinfo(memcg, page);
+		excess = soft_limit_excess(memcg);
+		/*
+		 * We have to update the tree if mz is on RB-tree or
+		 * mem is over its softlimit.
+		 */
+		if (excess || mz->on_tree) {
+			unsigned long flags;
+
+			spin_lock_irqsave(&mctz->lock, flags);
+			/* if on-tree, remove it */
+			if (mz->on_tree)
+				__mem_cgroup_remove_exceeded(mz, mctz);
+			/*
+			 * Insert again. mz->usage_in_excess will be updated.
+			 * If excess is 0, no tree ops.
+			 */
+			__mem_cgroup_insert_exceeded(mz, mctz, excess);
+			spin_unlock_irqrestore(&mctz->lock, flags);
+		}
+	}
+}
+
+static void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg)
+{
+	struct mem_cgroup_tree_per_node *mctz;
+	struct mem_cgroup_per_node *mz;
+	int nid;
+
+	for_each_node(nid) {
+		mz = mem_cgroup_nodeinfo(memcg, nid);
+		mctz = soft_limit_tree_node(nid);
+		if (mctz)
+			mem_cgroup_remove_exceeded(mz, mctz);
+	}
+}
+
+static struct mem_cgroup_per_node *
+__mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_node *mctz)
+{
+	struct mem_cgroup_per_node *mz;
+
+retry:
+	mz = NULL;
+	if (!mctz->rb_rightmost)
+		goto done;		/* Nothing to reclaim from */
+
+	mz = rb_entry(mctz->rb_rightmost,
+		      struct mem_cgroup_per_node, 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, mctz);
+	if (!soft_limit_excess(mz->memcg) ||
+	    !css_tryget_online(&mz->memcg->css))
+		goto retry;
+done:
+	return mz;
+}
+
+static struct mem_cgroup_per_node *
+mem_cgroup_largest_soft_limit_node(struct mem_cgroup_tree_per_node *mctz)
+{
+	struct mem_cgroup_per_node *mz;
+
+	spin_lock_irq(&mctz->lock);
+	mz = __mem_cgroup_largest_soft_limit_node(mctz);
+	spin_unlock_irq(&mctz->lock);
+	return mz;
+}
+
+static unsigned long memcg_sum_events(struct mem_cgroup *memcg,
+				      int event)
+{
+	return atomic_long_read(&memcg->events[event]);
+}
+
+static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg,
+					 struct page *page,
+					 bool compound, int nr_pages)
+{
+	/*
+	 * Here, RSS means 'mapped anon' and anon's SwapCache. Shmem/tmpfs is
+	 * counted as CACHE even if it's on ANON LRU.
+	 */
+	if (PageAnon(page))
+		__mod_memcg_state(memcg, MEMCG_RSS, nr_pages);
+	else {
+		__mod_memcg_state(memcg, MEMCG_CACHE, nr_pages);
+		if (PageSwapBacked(page))
+			__mod_memcg_state(memcg, NR_SHMEM, nr_pages);
+	}
+
+	if (compound) {
+		VM_BUG_ON_PAGE(!PageTransHuge(page), page);
+		__mod_memcg_state(memcg, MEMCG_RSS_HUGE, nr_pages);
+	}
+
+	/* pagein of a big page is an event. So, ignore page size */
+	if (nr_pages > 0)
+		__count_memcg_events(memcg, PGPGIN, 1);
+	else {
+		__count_memcg_events(memcg, PGPGOUT, 1);
+		nr_pages = -nr_pages; /* for event */
+	}
+
+	__this_cpu_add(memcg->stat_cpu->nr_page_events, nr_pages);
+}
+
+unsigned long mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg,
+					   int nid, unsigned int lru_mask)
+{
+	struct lruvec *lruvec = mem_cgroup_lruvec(NODE_DATA(nid), memcg);
+	unsigned long nr = 0;
+	enum lru_list lru;
+
+	VM_BUG_ON((unsigned)nid >= nr_node_ids);
+
+	for_each_lru(lru) {
+		if (!(BIT(lru) & lru_mask))
+			continue;
+		nr += mem_cgroup_get_lru_size(lruvec, lru);
+	}
+	return nr;
+}
+
+static unsigned long mem_cgroup_nr_lru_pages(struct mem_cgroup *memcg,
+			unsigned int lru_mask)
+{
+	unsigned long nr = 0;
+	int nid;
+
+	for_each_node_state(nid, N_MEMORY)
+		nr += mem_cgroup_node_nr_lru_pages(memcg, nid, lru_mask);
+	return nr;
+}
+
+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_cpu->nr_page_events);
+	next = __this_cpu_read(memcg->stat_cpu->targets[target]);
+	/* from time_after() in jiffies.h */
+	if ((long)(next - 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_cpu->targets[target], next);
+		return true;
+	}
+	return false;
+}
+
+/*
+ * Check events in order.
+ *
+ */
+static void memcg_check_events(struct mem_cgroup *memcg, struct page *page)
+{
+	/* 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
+		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
+	}
+}
+
+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 mem_cgroup_from_css(task_css(p, memory_cgrp_id));
+}
+EXPORT_SYMBOL(mem_cgroup_from_task);
+
+/**
+ * get_mem_cgroup_from_mm: Obtain a reference on given mm_struct's memcg.
+ * @mm: mm from which memcg should be extracted. It can be NULL.
+ *
+ * Obtain a reference on mm->memcg and returns it if successful. Otherwise
+ * root_mem_cgroup is returned. However if mem_cgroup is disabled, NULL is
+ * returned.
+ */
+struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
+{
+	struct mem_cgroup *memcg;
+
+	if (mem_cgroup_disabled())
+		return NULL;
+
+	rcu_read_lock();
+	do {
+		/*
+		 * Page cache insertions can happen withou an
+		 * actual mm context, e.g. during disk probing
+		 * on boot, loopback IO, acct() writes etc.
+		 */
+		if (unlikely(!mm))
+			memcg = root_mem_cgroup;
+		else {
+			memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
+			if (unlikely(!memcg))
+				memcg = root_mem_cgroup;
+		}
+	} while (!css_tryget(&memcg->css));
+	rcu_read_unlock();
+	return memcg;
+}
+EXPORT_SYMBOL(get_mem_cgroup_from_mm);
+
+/**
+ * get_mem_cgroup_from_page: Obtain a reference on given page's memcg.
+ * @page: page from which memcg should be extracted.
+ *
+ * Obtain a reference on page->memcg and returns it if successful. Otherwise
+ * root_mem_cgroup is returned.
+ */
+struct mem_cgroup *get_mem_cgroup_from_page(struct page *page)
+{
+	struct mem_cgroup *memcg = page->mem_cgroup;
+
+	if (mem_cgroup_disabled())
+		return NULL;
+
+	rcu_read_lock();
+	if (!memcg || !css_tryget_online(&memcg->css))
+		memcg = root_mem_cgroup;
+	rcu_read_unlock();
+	return memcg;
+}
+EXPORT_SYMBOL(get_mem_cgroup_from_page);
+
+/**
+ * If current->active_memcg is non-NULL, do not fallback to current->mm->memcg.
+ */
+static __always_inline struct mem_cgroup *get_mem_cgroup_from_current(void)
+{
+	if (unlikely(current->active_memcg)) {
+		struct mem_cgroup *memcg = root_mem_cgroup;
+
+		rcu_read_lock();
+		if (css_tryget_online(&current->active_memcg->css))
+			memcg = current->active_memcg;
+		rcu_read_unlock();
+		return memcg;
+	}
+	return get_mem_cgroup_from_mm(current->mm);
+}
+
+/**
+ * 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 node and a priority level in @reclaim to
+ * divide up the memcgs in the hierarchy among all concurrent
+ * reclaimers operating on the same node 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_reclaim_iter *uninitialized_var(iter);
+	struct cgroup_subsys_state *css = NULL;
+	struct mem_cgroup *memcg = NULL;
+	struct mem_cgroup *pos = NULL;
+
+	if (mem_cgroup_disabled())
+		return NULL;
+
+	if (!root)
+		root = root_mem_cgroup;
+
+	if (prev && !reclaim)
+		pos = prev;
+
+	if (!root->use_hierarchy && root != root_mem_cgroup) {
+		if (prev)
+			goto out;
+		return root;
+	}
+
+	rcu_read_lock();
+
+	if (reclaim) {
+		struct mem_cgroup_per_node *mz;
+
+		mz = mem_cgroup_nodeinfo(root, reclaim->pgdat->node_id);
+		iter = &mz->iter[reclaim->priority];
+
+		if (prev && reclaim->generation != iter->generation)
+			goto out_unlock;
+
+		while (1) {
+			pos = READ_ONCE(iter->position);
+			if (!pos || css_tryget(&pos->css))
+				break;
+			/*
+			 * css reference reached zero, so iter->position will
+			 * be cleared by ->css_released. However, we should not
+			 * rely on this happening soon, because ->css_released
+			 * is called from a work queue, and by busy-waiting we
+			 * might block it. So we clear iter->position right
+			 * away.
+			 */
+			(void)cmpxchg(&iter->position, pos, NULL);
+		}
+	}
+
+	if (pos)
+		css = &pos->css;
+
+	for (;;) {
+		css = css_next_descendant_pre(css, &root->css);
+		if (!css) {
+			/*
+			 * Reclaimers share the hierarchy walk, and a
+			 * new one might jump in right at the end of
+			 * the hierarchy - make sure they see at least
+			 * one group and restart from the beginning.
+			 */
+			if (!prev)
+				continue;
+			break;
+		}
+
+		/*
+		 * Verify the css and acquire a reference.  The root
+		 * is provided by the caller, so we know it's alive
+		 * and kicking, and don't take an extra reference.
+		 */
+		memcg = mem_cgroup_from_css(css);
+
+		if (css == &root->css)
+			break;
+
+		if (css_tryget(css))
+			break;
+
+		memcg = NULL;
+	}
+
+	if (reclaim) {
+		/*
+		 * The position could have already been updated by a competing
+		 * thread, so check that the value hasn't changed since we read
+		 * it to avoid reclaiming from the same cgroup twice.
+		 */
+		(void)cmpxchg(&iter->position, pos, memcg);
+
+		if (pos)
+			css_put(&pos->css);
+
+		if (!memcg)
+			iter->generation++;
+		else if (!prev)
+			reclaim->generation = iter->generation;
+	}
+
+out_unlock:
+	rcu_read_unlock();
+out:
+	if (prev && prev != root)
+		css_put(&prev->css);
+
+	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);
+}
+
+static void __invalidate_reclaim_iterators(struct mem_cgroup *from,
+					struct mem_cgroup *dead_memcg)
+{
+	struct mem_cgroup_reclaim_iter *iter;
+	struct mem_cgroup_per_node *mz;
+	int nid;
+	int i;
+
+	for_each_node(nid) {
+		mz = mem_cgroup_nodeinfo(from, nid);
+		for (i = 0; i <= DEF_PRIORITY; i++) {
+			iter = &mz->iter[i];
+			cmpxchg(&iter->position,
+				dead_memcg, NULL);
+		}
+	}
+}
+
+static void invalidate_reclaim_iterators(struct mem_cgroup *dead_memcg)
+{
+	struct mem_cgroup *memcg = dead_memcg;
+	struct mem_cgroup *last;
+
+	do {
+		__invalidate_reclaim_iterators(memcg, dead_memcg);
+		last = memcg;
+	} while ((memcg = parent_mem_cgroup(memcg)));
+
+	/*
+	 * When cgruop1 non-hierarchy mode is used,
+	 * parent_mem_cgroup() does not walk all the way up to the
+	 * cgroup root (root_mem_cgroup). So we have to handle
+	 * dead_memcg from cgroup root separately.
+	 */
+	if (last != root_mem_cgroup)
+		__invalidate_reclaim_iterators(root_mem_cgroup,
+						dead_memcg);
+}
+
+/**
+ * mem_cgroup_scan_tasks - iterate over tasks of a memory cgroup hierarchy
+ * @memcg: hierarchy root
+ * @fn: function to call for each task
+ * @arg: argument passed to @fn
+ *
+ * This function iterates over tasks attached to @memcg or to any of its
+ * descendants and calls @fn for each task. If @fn returns a non-zero
+ * value, the function breaks the iteration loop and returns the value.
+ * Otherwise, it will iterate over all tasks and return 0.
+ *
+ * This function must not be called for the root memory cgroup.
+ */
+int mem_cgroup_scan_tasks(struct mem_cgroup *memcg,
+			  int (*fn)(struct task_struct *, void *), void *arg)
+{
+	struct mem_cgroup *iter;
+	int ret = 0;
+
+	BUG_ON(memcg == root_mem_cgroup);
+
+	for_each_mem_cgroup_tree(iter, memcg) {
+		struct css_task_iter it;
+		struct task_struct *task;
+
+		css_task_iter_start(&iter->css, 0, &it);
+		while (!ret && (task = css_task_iter_next(&it)))
+			ret = fn(task, arg);
+		css_task_iter_end(&it);
+		if (ret) {
+			mem_cgroup_iter_break(memcg, iter);
+			break;
+		}
+	}
+	return ret;
+}
+
+/**
+ * mem_cgroup_page_lruvec - return lruvec for isolating/putting an LRU page
+ * @page: the page
+ * @pgdat: pgdat of the page
+ *
+ * This function is only safe when following the LRU page isolation
+ * and putback protocol: the LRU lock must be held, and the page must
+ * either be PageLRU() or the caller must have isolated/allocated it.
+ */
+struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgdat)
+{
+	struct mem_cgroup_per_node *mz;
+	struct mem_cgroup *memcg;
+	struct lruvec *lruvec;
+
+	if (mem_cgroup_disabled()) {
+		lruvec = &pgdat->lruvec;
+		goto out;
+	}
+
+	memcg = page->mem_cgroup;
+	/*
+	 * Swapcache readahead pages are added to the LRU - and
+	 * possibly migrated - before they are charged.
+	 */
+	if (!memcg)
+		memcg = root_mem_cgroup;
+
+	mz = mem_cgroup_page_nodeinfo(memcg, page);
+	lruvec = &mz->lruvec;
+out:
+	/*
+	 * Since a node can be onlined after the mem_cgroup was created,
+	 * we have to be prepared to initialize lruvec->zone here;
+	 * and if offlined then reonlined, we need to reinitialize it.
+	 */
+	if (unlikely(lruvec->pgdat != pgdat))
+		lruvec->pgdat = pgdat;
+	return lruvec;
+}
+
+/**
+ * mem_cgroup_update_lru_size - account for adding or removing an lru page
+ * @lruvec: mem_cgroup per zone lru vector
+ * @lru: index of lru list the page is sitting on
+ * @zid: zone id of the accounted pages
+ * @nr_pages: positive when adding or negative when removing
+ *
+ * This function must be called under lru_lock, just before a page is added
+ * to or just after a page is removed from an lru list (that ordering being
+ * so as to allow it to check that lru_size 0 is consistent with list_empty).
+ */
+void mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru,
+				int zid, int nr_pages)
+{
+	struct mem_cgroup_per_node *mz;
+	unsigned long *lru_size;
+	long size;
+
+	if (mem_cgroup_disabled())
+		return;
+
+	mz = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
+	lru_size = &mz->lru_zone_size[zid][lru];
+
+	if (nr_pages < 0)
+		*lru_size += nr_pages;
+
+	size = *lru_size;
+	if (WARN_ONCE(size < 0,
+		"%s(%p, %d, %d): lru_size %ld\n",
+		__func__, lruvec, lru, nr_pages, size)) {
+		VM_BUG_ON(1);
+		*lru_size = 0;
+	}
+
+	if (nr_pages > 0)
+		*lru_size += nr_pages;
+}
+
+bool task_in_mem_cgroup(struct task_struct *task, struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *task_memcg;
+	struct task_struct *p;
+	bool ret;
+
+	p = find_lock_task_mm(task);
+	if (p) {
+		task_memcg = 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.
+		 */
+		rcu_read_lock();
+		task_memcg = mem_cgroup_from_task(task);
+		css_get(&task_memcg->css);
+		rcu_read_unlock();
+	}
+	ret = mem_cgroup_is_descendant(task_memcg, memcg);
+	css_put(&task_memcg->css);
+	return ret;
+}
+
+/**
+ * mem_cgroup_margin - calculate chargeable space of a memory cgroup
+ * @memcg: 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 margin = 0;
+	unsigned long count;
+	unsigned long limit;
+
+	count = page_counter_read(&memcg->memory);
+	limit = READ_ONCE(memcg->memory.max);
+	if (count < limit)
+		margin = limit - count;
+
+	if (do_memsw_account()) {
+		count = page_counter_read(&memcg->memsw);
+		limit = READ_ONCE(memcg->memsw.max);
+		if (count <= limit)
+			margin = min(margin, limit - count);
+		else
+			margin = 0;
+	}
+
+	return margin;
+}
+
+/*
+ * A routine for checking "mem" is under move_account() or not.
+ *
+ * Checking a cgroup is mc.from or mc.to or under hierarchy of
+ * moving cgroups. This is for waiting at high-memory pressure
+ * caused by "move".
+ */
+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_is_descendant(from, memcg) ||
+		mem_cgroup_is_descendant(to, memcg);
+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;
+}
+
+static const unsigned int memcg1_stats[] = {
+	MEMCG_CACHE,
+	MEMCG_RSS,
+	MEMCG_RSS_HUGE,
+	NR_SHMEM,
+	NR_FILE_MAPPED,
+	NR_FILE_DIRTY,
+	NR_WRITEBACK,
+	MEMCG_SWAP,
+};
+
+static const char *const memcg1_stat_names[] = {
+	"cache",
+	"rss",
+	"rss_huge",
+	"shmem",
+	"mapped_file",
+	"dirty",
+	"writeback",
+	"swap",
+};
+
+#define K(x) ((x) << (PAGE_SHIFT-10))
+/**
+ * mem_cgroup_print_oom_info: Print OOM information relevant to memory controller.
+ * @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 mem_cgroup *iter;
+	unsigned int i;
+
+	rcu_read_lock();
+
+	if (p) {
+		pr_info("Task in ");
+		pr_cont_cgroup_path(task_cgroup(p, memory_cgrp_id));
+		pr_cont(" killed as a result of limit of ");
+	} else {
+		pr_info("Memory limit reached of cgroup ");
+	}
+
+	pr_cont_cgroup_path(memcg->css.cgroup);
+	pr_cont("\n");
+
+	rcu_read_unlock();
+
+	pr_info("memory: usage %llukB, limit %llukB, failcnt %lu\n",
+		K((u64)page_counter_read(&memcg->memory)),
+		K((u64)memcg->memory.max), memcg->memory.failcnt);
+	pr_info("memory+swap: usage %llukB, limit %llukB, failcnt %lu\n",
+		K((u64)page_counter_read(&memcg->memsw)),
+		K((u64)memcg->memsw.max), memcg->memsw.failcnt);
+	pr_info("kmem: usage %llukB, limit %llukB, failcnt %lu\n",
+		K((u64)page_counter_read(&memcg->kmem)),
+		K((u64)memcg->kmem.max), memcg->kmem.failcnt);
+
+	for_each_mem_cgroup_tree(iter, memcg) {
+		pr_info("Memory cgroup stats for ");
+		pr_cont_cgroup_path(iter->css.cgroup);
+		pr_cont(":");
+
+		for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) {
+			if (memcg1_stats[i] == MEMCG_SWAP && !do_swap_account)
+				continue;
+			pr_cont(" %s:%luKB", memcg1_stat_names[i],
+				K(memcg_page_state(iter, memcg1_stats[i])));
+		}
+
+		for (i = 0; i < NR_LRU_LISTS; i++)
+			pr_cont(" %s:%luKB", mem_cgroup_lru_names[i],
+				K(mem_cgroup_nr_lru_pages(iter, BIT(i))));
+
+		pr_cont("\n");
+	}
+}
+
+/*
+ * Return the memory (and swap, if configured) limit for a memcg.
+ */
+unsigned long mem_cgroup_get_max(struct mem_cgroup *memcg)
+{
+	unsigned long max;
+
+	max = memcg->memory.max;
+	if (mem_cgroup_swappiness(memcg)) {
+		unsigned long memsw_max;
+		unsigned long swap_max;
+
+		memsw_max = memcg->memsw.max;
+		swap_max = memcg->swap.max;
+		swap_max = min(swap_max, (unsigned long)total_swap_pages);
+		max = min(max + swap_max, memsw_max);
+	}
+	return max;
+}
+
+static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
+				     int order)
+{
+	struct oom_control oc = {
+		.zonelist = NULL,
+		.nodemask = NULL,
+		.memcg = memcg,
+		.gfp_mask = gfp_mask,
+		.order = order,
+	};
+	bool ret;
+
+	if (mutex_lock_killable(&oom_lock))
+		return true;
+	/*
+	 * A few threads which were not waiting at mutex_lock_killable() can
+	 * fail to bail out. Therefore, check again after holding oom_lock.
+	 */
+	ret = should_force_charge() || out_of_memory(&oc);
+	mutex_unlock(&oom_lock);
+	return ret;
+}
+
+#if MAX_NUMNODES > 1
+
+/**
+ * test_mem_cgroup_node_reclaimable
+ * @memcg: 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;
+
+}
+
+/*
+ * 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_MEMORY];
+
+	for_each_node_mask(nid, node_states[N_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_in(node, memcg->scan_nodes);
+	/*
+	 * mem_cgroup_may_update_nodemask might have seen no reclaimmable pages
+	 * last time it really checked all the LRUs due to rate limiting.
+	 * Fallback to the current node in that case for simplicity.
+	 */
+	if (unlikely(node == MAX_NUMNODES))
+		node = numa_node_id();
+
+	memcg->last_scanned_node = node;
+	return node;
+}
+#else
+int mem_cgroup_select_victim_node(struct mem_cgroup *memcg)
+{
+	return 0;
+}
+#endif
+
+static int mem_cgroup_soft_reclaim(struct mem_cgroup *root_memcg,
+				   pg_data_t *pgdat,
+				   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 = {
+		.pgdat = pgdat,
+		.priority = 0,
+	};
+
+	excess = soft_limit_excess(root_memcg);
+
+	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;
+		}
+		total += mem_cgroup_shrink_node(victim, gfp_mask, false,
+					pgdat, &nr_scanned);
+		*total_scanned += nr_scanned;
+		if (!soft_limit_excess(root_memcg))
+			break;
+	}
+	mem_cgroup_iter_break(root_memcg, victim);
+	return total;
+}
+
+#ifdef CONFIG_LOCKDEP
+static struct lockdep_map memcg_oom_lock_dep_map = {
+	.name = "memcg_oom_lock",
+};
+#endif
+
+static DEFINE_SPINLOCK(memcg_oom_lock);
+
+/*
+ * Check OOM-Killer is already running under our hierarchy.
+ * If someone is running, return false.
+ */
+static bool mem_cgroup_oom_trylock(struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *iter, *failed = NULL;
+
+	spin_lock(&memcg_oom_lock);
+
+	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) {
+		/*
+		 * 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;
+		}
+	} else
+		mutex_acquire(&memcg_oom_lock_dep_map, 0, 1, _RET_IP_);
+
+	spin_unlock(&memcg_oom_lock);
+
+	return !failed;
+}
+
+static void mem_cgroup_oom_unlock(struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *iter;
+
+	spin_lock(&memcg_oom_lock);
+	mutex_release(&memcg_oom_lock_dep_map, 1, _RET_IP_);
+	for_each_mem_cgroup_tree(iter, memcg)
+		iter->oom_lock = false;
+	spin_unlock(&memcg_oom_lock);
+}
+
+static void mem_cgroup_mark_under_oom(struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *iter;
+
+	spin_lock(&memcg_oom_lock);
+	for_each_mem_cgroup_tree(iter, memcg)
+		iter->under_oom++;
+	spin_unlock(&memcg_oom_lock);
+}
+
+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. Watch for underflow.
+	 */
+	spin_lock(&memcg_oom_lock);
+	for_each_mem_cgroup_tree(iter, memcg)
+		if (iter->under_oom > 0)
+			iter->under_oom--;
+	spin_unlock(&memcg_oom_lock);
+}
+
+static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq);
+
+struct oom_wait_info {
+	struct mem_cgroup *memcg;
+	wait_queue_entry_t	wait;
+};
+
+static int memcg_oom_wake_function(wait_queue_entry_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;
+
+	if (!mem_cgroup_is_descendant(wake_memcg, oom_wait_memcg) &&
+	    !mem_cgroup_is_descendant(oom_wait_memcg, wake_memcg))
+		return 0;
+	return autoremove_wake_function(wait, mode, sync, arg);
+}
+
+static void memcg_oom_recover(struct mem_cgroup *memcg)
+{
+	/*
+	 * For the following lockless ->under_oom test, the only required
+	 * guarantee is that it must see the state asserted by an OOM when
+	 * this function is called as a result of userland actions
+	 * triggered by the notification of the OOM.  This is trivially
+	 * achieved by invoking mem_cgroup_mark_under_oom() before
+	 * triggering notification.
+	 */
+	if (memcg && memcg->under_oom)
+		__wake_up(&memcg_oom_waitq, TASK_NORMAL, 0, memcg);
+}
+
+enum oom_status {
+	OOM_SUCCESS,
+	OOM_FAILED,
+	OOM_ASYNC,
+	OOM_SKIPPED
+};
+
+static enum oom_status mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order)
+{
+	enum oom_status ret;
+	bool locked;
+
+	if (order > PAGE_ALLOC_COSTLY_ORDER)
+		return OOM_SKIPPED;
+
+	/*
+	 * We are in the middle of the charge context here, so we
+	 * don't want to block when potentially sitting on a callstack
+	 * that holds all kinds of filesystem and mm locks.
+	 *
+	 * cgroup1 allows disabling the OOM killer and waiting for outside
+	 * handling until the charge can succeed; remember the context and put
+	 * the task to sleep at the end of the page fault when all locks are
+	 * released.
+	 *
+	 * On the other hand, in-kernel OOM killer allows for an async victim
+	 * memory reclaim (oom_reaper) and that means that we are not solely
+	 * relying on the oom victim to make a forward progress and we can
+	 * invoke the oom killer here.
+	 *
+	 * Please note that mem_cgroup_out_of_memory might fail to find a
+	 * victim and then we have to bail out from the charge path.
+	 */
+	if (memcg->oom_kill_disable) {
+		if (!current->in_user_fault)
+			return OOM_SKIPPED;
+		css_get(&memcg->css);
+		current->memcg_in_oom = memcg;
+		current->memcg_oom_gfp_mask = mask;
+		current->memcg_oom_order = order;
+
+		return OOM_ASYNC;
+	}
+
+	mem_cgroup_mark_under_oom(memcg);
+
+	locked = mem_cgroup_oom_trylock(memcg);
+
+	if (locked)
+		mem_cgroup_oom_notify(memcg);
+
+	mem_cgroup_unmark_under_oom(memcg);
+	if (mem_cgroup_out_of_memory(memcg, mask, order))
+		ret = OOM_SUCCESS;
+	else
+		ret = OOM_FAILED;
+
+	if (locked)
+		mem_cgroup_oom_unlock(memcg);
+
+	return ret;
+}
+
+/**
+ * mem_cgroup_oom_synchronize - complete memcg OOM handling
+ * @handle: actually kill/wait or just clean up the OOM state
+ *
+ * This has to be called at the end of a page fault if the memcg OOM
+ * handler was enabled.
+ *
+ * Memcg supports userspace OOM handling where failed allocations must
+ * sleep on a waitqueue until the userspace task resolves the
+ * situation.  Sleeping directly in the charge context with all kinds
+ * of locks held is not a good idea, instead we remember an OOM state
+ * in the task and mem_cgroup_oom_synchronize() has to be called at
+ * the end of the page fault to complete the OOM handling.
+ *
+ * Returns %true if an ongoing memcg OOM situation was detected and
+ * completed, %false otherwise.
+ */
+bool mem_cgroup_oom_synchronize(bool handle)
+{
+	struct mem_cgroup *memcg = current->memcg_in_oom;
+	struct oom_wait_info owait;
+	bool locked;
+
+	/* OOM is global, do not handle */
+	if (!memcg)
+		return false;
+
+	if (!handle)
+		goto cleanup;
+
+	owait.memcg = memcg;
+	owait.wait.flags = 0;
+	owait.wait.func = memcg_oom_wake_function;
+	owait.wait.private = current;
+	INIT_LIST_HEAD(&owait.wait.entry);
+
+	prepare_to_wait(&memcg_oom_waitq, &owait.wait, TASK_KILLABLE);
+	mem_cgroup_mark_under_oom(memcg);
+
+	locked = mem_cgroup_oom_trylock(memcg);
+
+	if (locked)
+		mem_cgroup_oom_notify(memcg);
+
+	if (locked && !memcg->oom_kill_disable) {
+		mem_cgroup_unmark_under_oom(memcg);
+		finish_wait(&memcg_oom_waitq, &owait.wait);
+		mem_cgroup_out_of_memory(memcg, current->memcg_oom_gfp_mask,
+					 current->memcg_oom_order);
+	} else {
+		schedule();
+		mem_cgroup_unmark_under_oom(memcg);
+		finish_wait(&memcg_oom_waitq, &owait.wait);
+	}
+
+	if (locked) {
+		mem_cgroup_oom_unlock(memcg);
+		/*
+		 * There is no guarantee that an OOM-lock contender
+		 * sees the wakeups triggered by the OOM kill
+		 * uncharges.  Wake any sleepers explicitely.
+		 */
+		memcg_oom_recover(memcg);
+	}
+cleanup:
+	current->memcg_in_oom = NULL;
+	css_put(&memcg->css);
+	return true;
+}
+
+/**
+ * mem_cgroup_get_oom_group - get a memory cgroup to clean up after OOM
+ * @victim: task to be killed by the OOM killer
+ * @oom_domain: memcg in case of memcg OOM, NULL in case of system-wide OOM
+ *
+ * Returns a pointer to a memory cgroup, which has to be cleaned up
+ * by killing all belonging OOM-killable tasks.
+ *
+ * Caller has to call mem_cgroup_put() on the returned non-NULL memcg.
+ */
+struct mem_cgroup *mem_cgroup_get_oom_group(struct task_struct *victim,
+					    struct mem_cgroup *oom_domain)
+{
+	struct mem_cgroup *oom_group = NULL;
+	struct mem_cgroup *memcg;
+
+	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
+		return NULL;
+
+	if (!oom_domain)
+		oom_domain = root_mem_cgroup;
+
+	rcu_read_lock();
+
+	memcg = mem_cgroup_from_task(victim);
+	if (memcg == root_mem_cgroup)
+		goto out;
+
+	/*
+	 * Traverse the memory cgroup hierarchy from the victim task's
+	 * cgroup up to the OOMing cgroup (or root) to find the
+	 * highest-level memory cgroup with oom.group set.
+	 */
+	for (; memcg; memcg = parent_mem_cgroup(memcg)) {
+		if (memcg->oom_group)
+			oom_group = memcg;
+
+		if (memcg == oom_domain)
+			break;
+	}
+
+	if (oom_group)
+		css_get(&oom_group->css);
+out:
+	rcu_read_unlock();
+
+	return oom_group;
+}
+
+void mem_cgroup_print_oom_group(struct mem_cgroup *memcg)
+{
+	pr_info("Tasks in ");
+	pr_cont_cgroup_path(memcg->css.cgroup);
+	pr_cont(" are going to be killed due to memory.oom.group set\n");
+}
+
+/**
+ * lock_page_memcg - lock a page->mem_cgroup binding
+ * @page: the page
+ *
+ * This function protects unlocked LRU pages from being moved to
+ * another cgroup.
+ *
+ * It ensures lifetime of the returned memcg. Caller is responsible
+ * for the lifetime of the page; __unlock_page_memcg() is available
+ * when @page might get freed inside the locked section.
+ */
+struct mem_cgroup *lock_page_memcg(struct page *page)
+{
+	struct mem_cgroup *memcg;
+	unsigned long flags;
+
+	/*
+	 * The RCU lock is held throughout the transaction.  The fast
+	 * path can get away without acquiring the memcg->move_lock
+	 * because page moving starts with an RCU grace period.
+	 *
+	 * The RCU lock also protects the memcg from being freed when
+	 * the page state that is going to change is the only thing
+	 * preventing the page itself from being freed. E.g. writeback
+	 * doesn't hold a page reference and relies on PG_writeback to
+	 * keep off truncation, migration and so forth.
+         */
+	rcu_read_lock();
+
+	if (mem_cgroup_disabled())
+		return NULL;
+again:
+	memcg = page->mem_cgroup;
+	if (unlikely(!memcg))
+		return NULL;
+
+	if (atomic_read(&memcg->moving_account) <= 0)
+		return memcg;
+
+	spin_lock_irqsave(&memcg->move_lock, flags);
+	if (memcg != page->mem_cgroup) {
+		spin_unlock_irqrestore(&memcg->move_lock, flags);
+		goto again;
+	}
+
+	/*
+	 * When charge migration first begins, we can have locked and
+	 * unlocked page stat updates happening concurrently.  Track
+	 * the task who has the lock for unlock_page_memcg().
+	 */
+	memcg->move_lock_task = current;
+	memcg->move_lock_flags = flags;
+
+	return memcg;
+}
+EXPORT_SYMBOL(lock_page_memcg);
+
+/**
+ * __unlock_page_memcg - unlock and unpin a memcg
+ * @memcg: the memcg
+ *
+ * Unlock and unpin a memcg returned by lock_page_memcg().
+ */
+void __unlock_page_memcg(struct mem_cgroup *memcg)
+{
+	if (memcg && memcg->move_lock_task == current) {
+		unsigned long flags = memcg->move_lock_flags;
+
+		memcg->move_lock_task = NULL;
+		memcg->move_lock_flags = 0;
+
+		spin_unlock_irqrestore(&memcg->move_lock, flags);
+	}
+
+	rcu_read_unlock();
+}
+
+/**
+ * unlock_page_memcg - unlock a page->mem_cgroup binding
+ * @page: the page
+ */
+void unlock_page_memcg(struct page *page)
+{
+	__unlock_page_memcg(page->mem_cgroup);
+}
+EXPORT_SYMBOL(unlock_page_memcg);
+
+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);
+
+/**
+ * consume_stock: Try to consume stocked charge on this cpu.
+ * @memcg: memcg to consume from.
+ * @nr_pages: how many pages to charge.
+ *
+ * The charges will only happen if @memcg matches the current cpu's memcg
+ * stock, and at least @nr_pages are available in that stock.  Failure to
+ * service an allocation will refill the stock.
+ *
+ * returns true if successful, false otherwise.
+ */
+static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages)
+{
+	struct memcg_stock_pcp *stock;
+	unsigned long flags;
+	bool ret = false;
+
+	if (nr_pages > MEMCG_CHARGE_BATCH)
+		return ret;
+
+	local_irq_save(flags);
+
+	stock = this_cpu_ptr(&memcg_stock);
+	if (memcg == stock->cached && stock->nr_pages >= nr_pages) {
+		stock->nr_pages -= nr_pages;
+		ret = true;
+	}
+
+	local_irq_restore(flags);
+
+	return ret;
+}
+
+/*
+ * Returns stocks cached in percpu and reset cached information.
+ */
+static void drain_stock(struct memcg_stock_pcp *stock)
+{
+	struct mem_cgroup *old = stock->cached;
+
+	if (stock->nr_pages) {
+		page_counter_uncharge(&old->memory, stock->nr_pages);
+		if (do_memsw_account())
+			page_counter_uncharge(&old->memsw, stock->nr_pages);
+		css_put_many(&old->css, stock->nr_pages);
+		stock->nr_pages = 0;
+	}
+	stock->cached = NULL;
+}
+
+static void drain_local_stock(struct work_struct *dummy)
+{
+	struct memcg_stock_pcp *stock;
+	unsigned long flags;
+
+	/*
+	 * The only protection from memory hotplug vs. drain_stock races is
+	 * that we always operate on local CPU stock here with IRQ disabled
+	 */
+	local_irq_save(flags);
+
+	stock = this_cpu_ptr(&memcg_stock);
+	drain_stock(stock);
+	clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags);
+
+	local_irq_restore(flags);
+}
+
+/*
+ * Cache charges(val) 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;
+	unsigned long flags;
+
+	local_irq_save(flags);
+
+	stock = this_cpu_ptr(&memcg_stock);
+	if (stock->cached != memcg) { /* reset if necessary */
+		drain_stock(stock);
+		stock->cached = memcg;
+	}
+	stock->nr_pages += nr_pages;
+
+	if (stock->nr_pages > MEMCG_CHARGE_BATCH)
+		drain_stock(stock);
+
+	local_irq_restore(flags);
+}
+
+/*
+ * Drains all per-CPU charge caches for given root_memcg resp. subtree
+ * of the hierarchy under it.
+ */
+static void drain_all_stock(struct mem_cgroup *root_memcg)
+{
+	int cpu, curcpu;
+
+	/* If someone's already draining, avoid adding running more workers. */
+	if (!mutex_trylock(&percpu_charge_mutex))
+		return;
+	/*
+	 * Notify other cpus that system-wide "drain" is running
+	 * We do not care about races with the cpu hotplug because cpu down
+	 * as well as workers from this path always operate on the local
+	 * per-cpu data. CPU up doesn't touch memcg_stock at all.
+	 */
+	curcpu = get_cpu();
+	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 || !css_tryget(&memcg->css))
+			continue;
+		if (!mem_cgroup_is_descendant(memcg, root_memcg)) {
+			css_put(&memcg->css);
+			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);
+		}
+		css_put(&memcg->css);
+	}
+	put_cpu();
+	mutex_unlock(&percpu_charge_mutex);
+}
+
+static int memcg_hotplug_cpu_dead(unsigned int cpu)
+{
+	struct memcg_stock_pcp *stock;
+	struct mem_cgroup *memcg;
+
+	stock = &per_cpu(memcg_stock, cpu);
+	drain_stock(stock);
+
+	for_each_mem_cgroup(memcg) {
+		int i;
+
+		for (i = 0; i < MEMCG_NR_STAT; i++) {
+			int nid;
+			long x;
+
+			x = this_cpu_xchg(memcg->stat_cpu->count[i], 0);
+			if (x)
+				atomic_long_add(x, &memcg->stat[i]);
+
+			if (i >= NR_VM_NODE_STAT_ITEMS)
+				continue;
+
+			for_each_node(nid) {
+				struct mem_cgroup_per_node *pn;
+
+				pn = mem_cgroup_nodeinfo(memcg, nid);
+				x = this_cpu_xchg(pn->lruvec_stat_cpu->count[i], 0);
+				if (x)
+					atomic_long_add(x, &pn->lruvec_stat[i]);
+			}
+		}
+
+		for (i = 0; i < NR_VM_EVENT_ITEMS; i++) {
+			long x;
+
+			x = this_cpu_xchg(memcg->stat_cpu->events[i], 0);
+			if (x)
+				atomic_long_add(x, &memcg->events[i]);
+		}
+	}
+
+	return 0;
+}
+
+static void reclaim_high(struct mem_cgroup *memcg,
+			 unsigned int nr_pages,
+			 gfp_t gfp_mask)
+{
+	do {
+		if (page_counter_read(&memcg->memory) <= memcg->high)
+			continue;
+		memcg_memory_event(memcg, MEMCG_HIGH);
+		try_to_free_mem_cgroup_pages(memcg, nr_pages, gfp_mask, true);
+	} while ((memcg = parent_mem_cgroup(memcg)));
+}
+
+static void high_work_func(struct work_struct *work)
+{
+	struct mem_cgroup *memcg;
+
+	memcg = container_of(work, struct mem_cgroup, high_work);
+	reclaim_high(memcg, MEMCG_CHARGE_BATCH, GFP_KERNEL);
+}
+
+/*
+ * Scheduled by try_charge() to be executed from the userland return path
+ * and reclaims memory over the high limit.
+ */
+void mem_cgroup_handle_over_high(void)
+{
+	unsigned int nr_pages = current->memcg_nr_pages_over_high;
+	struct mem_cgroup *memcg;
+
+	if (likely(!nr_pages))
+		return;
+
+	memcg = get_mem_cgroup_from_mm(current->mm);
+	reclaim_high(memcg, nr_pages, GFP_KERNEL);
+	css_put(&memcg->css);
+	current->memcg_nr_pages_over_high = 0;
+}
+
+static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
+		      unsigned int nr_pages)
+{
+	unsigned int batch = max(MEMCG_CHARGE_BATCH, nr_pages);
+	int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
+	struct mem_cgroup *mem_over_limit;
+	struct page_counter *counter;
+	unsigned long nr_reclaimed;
+	bool may_swap = true;
+	bool drained = false;
+	bool oomed = false;
+	enum oom_status oom_status;
+
+	if (mem_cgroup_is_root(memcg))
+		return 0;
+retry:
+	if (consume_stock(memcg, nr_pages))
+		return 0;
+
+	if (!do_memsw_account() ||
+	    page_counter_try_charge(&memcg->memsw, batch, &counter)) {
+		if (page_counter_try_charge(&memcg->memory, batch, &counter))
+			goto done_restock;
+		if (do_memsw_account())
+			page_counter_uncharge(&memcg->memsw, batch);
+		mem_over_limit = mem_cgroup_from_counter(counter, memory);
+	} else {
+		mem_over_limit = mem_cgroup_from_counter(counter, memsw);
+		may_swap = false;
+	}
+
+	if (batch > nr_pages) {
+		batch = nr_pages;
+		goto retry;
+	}
+
+	/*
+	 * Memcg doesn't have a dedicated reserve for atomic
+	 * allocations. But like the global atomic pool, we need to
+	 * put the burden of reclaim on regular allocation requests
+	 * and let these go through as privileged allocations.
+	 */
+	if (gfp_mask & __GFP_ATOMIC)
+		goto force;
+
+	/*
+	 * Unlike in global OOM situations, memcg is not in a physical
+	 * memory shortage.  Allow dying and OOM-killed tasks to
+	 * bypass the last charges so that they can exit quickly and
+	 * free their memory.
+	 */
+	if (unlikely(should_force_charge()))
+		goto force;
+
+	/*
+	 * Prevent unbounded recursion when reclaim operations need to
+	 * allocate memory. This might exceed the limits temporarily,
+	 * but we prefer facilitating memory reclaim and getting back
+	 * under the limit over triggering OOM kills in these cases.
+	 */
+	if (unlikely(current->flags & PF_MEMALLOC))
+		goto force;
+
+	if (unlikely(task_in_memcg_oom(current)))
+		goto nomem;
+
+	if (!gfpflags_allow_blocking(gfp_mask))
+		goto nomem;
+
+	memcg_memory_event(mem_over_limit, MEMCG_MAX);
+
+	nr_reclaimed = try_to_free_mem_cgroup_pages(mem_over_limit, nr_pages,
+						    gfp_mask, may_swap);
+
+	if (mem_cgroup_margin(mem_over_limit) >= nr_pages)
+		goto retry;
+
+	if (!drained) {
+		drain_all_stock(mem_over_limit);
+		drained = true;
+		goto retry;
+	}
+
+	if (gfp_mask & __GFP_NORETRY)
+		goto nomem;
+	/*
+	 * 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_reclaimed && nr_pages <= (1 << PAGE_ALLOC_COSTLY_ORDER))
+		goto 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))
+		goto retry;
+
+	if (nr_retries--)
+		goto retry;
+
+	if (gfp_mask & __GFP_RETRY_MAYFAIL && oomed)
+		goto nomem;
+
+	if (gfp_mask & __GFP_NOFAIL)
+		goto force;
+
+	if (fatal_signal_pending(current))
+		goto force;
+
+	memcg_memory_event(mem_over_limit, MEMCG_OOM);
+
+	/*
+	 * keep retrying as long as the memcg oom killer is able to make
+	 * a forward progress or bypass the charge if the oom killer
+	 * couldn't make any progress.
+	 */
+	oom_status = mem_cgroup_oom(mem_over_limit, gfp_mask,
+		       get_order(nr_pages * PAGE_SIZE));
+	switch (oom_status) {
+	case OOM_SUCCESS:
+		nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
+		oomed = true;
+		goto retry;
+	case OOM_FAILED:
+		goto force;
+	default:
+		goto nomem;
+	}
+nomem:
+	if (!(gfp_mask & __GFP_NOFAIL))
+		return -ENOMEM;
+force:
+	/*
+	 * The allocation either can't fail or will lead to more memory
+	 * being freed very soon.  Allow memory usage go over the limit
+	 * temporarily by force charging it.
+	 */
+	page_counter_charge(&memcg->memory, nr_pages);
+	if (do_memsw_account())
+		page_counter_charge(&memcg->memsw, nr_pages);
+	css_get_many(&memcg->css, nr_pages);
+
+	return 0;
+
+done_restock:
+	css_get_many(&memcg->css, batch);
+	if (batch > nr_pages)
+		refill_stock(memcg, batch - nr_pages);
+
+	/*
+	 * If the hierarchy is above the normal consumption range, schedule
+	 * reclaim on returning to userland.  We can perform reclaim here
+	 * if __GFP_RECLAIM but let's always punt for simplicity and so that
+	 * GFP_KERNEL can consistently be used during reclaim.  @memcg is
+	 * not recorded as it most likely matches current's and won't
+	 * change in the meantime.  As high limit is checked again before
+	 * reclaim, the cost of mismatch is negligible.
+	 */
+	do {
+		if (page_counter_read(&memcg->memory) > memcg->high) {
+			/* Don't bother a random interrupted task */
+			if (in_interrupt()) {
+				schedule_work(&memcg->high_work);
+				break;
+			}
+			current->memcg_nr_pages_over_high += batch;
+			set_notify_resume(current);
+			break;
+		}
+	} while ((memcg = parent_mem_cgroup(memcg)));
+
+	return 0;
+}
+
+static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages)
+{
+	if (mem_cgroup_is_root(memcg))
+		return;
+
+	page_counter_uncharge(&memcg->memory, nr_pages);
+	if (do_memsw_account())
+		page_counter_uncharge(&memcg->memsw, nr_pages);
+
+	css_put_many(&memcg->css, nr_pages);
+}
+
+static void lock_page_lru(struct page *page, int *isolated)
+{
+	struct zone *zone = page_zone(page);
+
+	spin_lock_irq(zone_lru_lock(zone));
+	if (PageLRU(page)) {
+		struct lruvec *lruvec;
+
+		lruvec = mem_cgroup_page_lruvec(page, zone->zone_pgdat);
+		ClearPageLRU(page);
+		del_page_from_lru_list(page, lruvec, page_lru(page));
+		*isolated = 1;
+	} else
+		*isolated = 0;
+}
+
+static void unlock_page_lru(struct page *page, int isolated)
+{
+	struct zone *zone = page_zone(page);
+
+	if (isolated) {
+		struct lruvec *lruvec;
+
+		lruvec = mem_cgroup_page_lruvec(page, zone->zone_pgdat);
+		VM_BUG_ON_PAGE(PageLRU(page), page);
+		SetPageLRU(page);
+		add_page_to_lru_list(page, lruvec, page_lru(page));
+	}
+	spin_unlock_irq(zone_lru_lock(zone));
+}
+
+static void commit_charge(struct page *page, struct mem_cgroup *memcg,
+			  bool lrucare)
+{
+	int isolated;
+
+	VM_BUG_ON_PAGE(page->mem_cgroup, page);
+
+	/*
+	 * 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)
+		lock_page_lru(page, &isolated);
+
+	/*
+	 * Nobody should be changing or seriously looking at
+	 * page->mem_cgroup at this point:
+	 *
+	 * - the page is uncharged
+	 *
+	 * - the page is off-LRU
+	 *
+	 * - an anonymous fault has exclusive page access, except for
+	 *   a locked page table
+	 *
+	 * - a page cache insertion, a swapin fault, or a migration
+	 *   have the page locked
+	 */
+	page->mem_cgroup = memcg;
+
+	if (lrucare)
+		unlock_page_lru(page, isolated);
+}
+
+#ifdef CONFIG_MEMCG_KMEM
+static int memcg_alloc_cache_id(void)
+{
+	int id, size;
+	int err;
+
+	id = ida_simple_get(&memcg_cache_ida,
+			    0, MEMCG_CACHES_MAX_SIZE, GFP_KERNEL);
+	if (id < 0)
+		return id;
+
+	if (id < memcg_nr_cache_ids)
+		return id;
+
+	/*
+	 * There's no space for the new id in memcg_caches arrays,
+	 * so we have to grow them.
+	 */
+	down_write(&memcg_cache_ids_sem);
+
+	size = 2 * (id + 1);
+	if (size < MEMCG_CACHES_MIN_SIZE)
+		size = MEMCG_CACHES_MIN_SIZE;
+	else if (size > MEMCG_CACHES_MAX_SIZE)
+		size = MEMCG_CACHES_MAX_SIZE;
+
+	err = memcg_update_all_caches(size);
+	if (!err)
+		err = memcg_update_all_list_lrus(size);
+	if (!err)
+		memcg_nr_cache_ids = size;
+
+	up_write(&memcg_cache_ids_sem);
+
+	if (err) {
+		ida_simple_remove(&memcg_cache_ida, id);
+		return err;
+	}
+	return id;
+}
+
+static void memcg_free_cache_id(int id)
+{
+	ida_simple_remove(&memcg_cache_ida, id);
+}
+
+struct memcg_kmem_cache_create_work {
+	struct mem_cgroup *memcg;
+	struct kmem_cache *cachep;
+	struct work_struct work;
+};
+
+static void memcg_kmem_cache_create_func(struct work_struct *w)
+{
+	struct memcg_kmem_cache_create_work *cw =
+		container_of(w, struct memcg_kmem_cache_create_work, work);
+	struct mem_cgroup *memcg = cw->memcg;
+	struct kmem_cache *cachep = cw->cachep;
+
+	memcg_create_kmem_cache(memcg, cachep);
+
+	css_put(&memcg->css);
+	kfree(cw);
+}
+
+/*
+ * Enqueue the creation of a per-memcg kmem_cache.
+ */
+static void __memcg_schedule_kmem_cache_create(struct mem_cgroup *memcg,
+					       struct kmem_cache *cachep)
+{
+	struct memcg_kmem_cache_create_work *cw;
+
+	cw = kmalloc(sizeof(*cw), GFP_NOWAIT | __GFP_NOWARN);
+	if (!cw)
+		return;
+
+	css_get(&memcg->css);
+
+	cw->memcg = memcg;
+	cw->cachep = cachep;
+	INIT_WORK(&cw->work, memcg_kmem_cache_create_func);
+
+	queue_work(memcg_kmem_cache_wq, &cw->work);
+}
+
+static void memcg_schedule_kmem_cache_create(struct mem_cgroup *memcg,
+					     struct kmem_cache *cachep)
+{
+	/*
+	 * We need to stop accounting when we kmalloc, because if the
+	 * corresponding kmalloc cache is not yet created, the first allocation
+	 * in __memcg_schedule_kmem_cache_create will recurse.
+	 *
+	 * However, it is better to enclose the whole function. Depending on
+	 * the debugging options enabled, INIT_WORK(), for instance, can
+	 * trigger an allocation. This too, will make us recurse. Because at
+	 * this point we can't allow ourselves back into memcg_kmem_get_cache,
+	 * the safest choice is to do it like this, wrapping the whole function.
+	 */
+	current->memcg_kmem_skip_account = 1;
+	__memcg_schedule_kmem_cache_create(memcg, cachep);
+	current->memcg_kmem_skip_account = 0;
+}
+
+static inline bool memcg_kmem_bypass(void)
+{
+	if (in_interrupt() || !current->mm || (current->flags & PF_KTHREAD))
+		return true;
+	return false;
+}
+
+/**
+ * memcg_kmem_get_cache: select the correct per-memcg cache for allocation
+ * @cachep: the original global kmem cache
+ *
+ * Return the kmem_cache we're supposed to use for a slab allocation.
+ * We try to use the current memcg's version of the cache.
+ *
+ * If the cache does not exist yet, if we are the first user of it, we
+ * create it asynchronously in a workqueue and let the current allocation
+ * go through with the original cache.
+ *
+ * This function takes a reference to the cache it returns to assure it
+ * won't get destroyed while we are working with it. Once the caller is
+ * done with it, memcg_kmem_put_cache() must be called to release the
+ * reference.
+ */
+struct kmem_cache *memcg_kmem_get_cache(struct kmem_cache *cachep)
+{
+	struct mem_cgroup *memcg;
+	struct kmem_cache *memcg_cachep;
+	int kmemcg_id;
+
+	VM_BUG_ON(!is_root_cache(cachep));
+
+	if (memcg_kmem_bypass())
+		return cachep;
+
+	if (current->memcg_kmem_skip_account)
+		return cachep;
+
+	memcg = get_mem_cgroup_from_current();
+	kmemcg_id = READ_ONCE(memcg->kmemcg_id);
+	if (kmemcg_id < 0)
+		goto out;
+
+	memcg_cachep = cache_from_memcg_idx(cachep, kmemcg_id);
+	if (likely(memcg_cachep))
+		return memcg_cachep;
+
+	/*
+	 * If we are in a safe context (can wait, and not in interrupt
+	 * context), we could be be predictable and return right away.
+	 * This would guarantee that the allocation being performed
+	 * already belongs in the new cache.
+	 *
+	 * However, there are some clashes that can arrive from locking.
+	 * For instance, because we acquire the slab_mutex while doing
+	 * memcg_create_kmem_cache, this means no further allocation
+	 * could happen with the slab_mutex held. So it's better to
+	 * defer everything.
+	 */
+	memcg_schedule_kmem_cache_create(memcg, cachep);
+out:
+	css_put(&memcg->css);
+	return cachep;
+}
+
+/**
+ * memcg_kmem_put_cache: drop reference taken by memcg_kmem_get_cache
+ * @cachep: the cache returned by memcg_kmem_get_cache
+ */
+void memcg_kmem_put_cache(struct kmem_cache *cachep)
+{
+	if (!is_root_cache(cachep))
+		css_put(&cachep->memcg_params.memcg->css);
+}
+
+/**
+ * memcg_kmem_charge_memcg: charge a kmem page
+ * @page: page to charge
+ * @gfp: reclaim mode
+ * @order: allocation order
+ * @memcg: memory cgroup to charge
+ *
+ * Returns 0 on success, an error code on failure.
+ */
+int memcg_kmem_charge_memcg(struct page *page, gfp_t gfp, int order,
+			    struct mem_cgroup *memcg)
+{
+	unsigned int nr_pages = 1 << order;
+	struct page_counter *counter;
+	int ret;
+
+	ret = try_charge(memcg, gfp, nr_pages);
+	if (ret)
+		return ret;
+
+	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) &&
+	    !page_counter_try_charge(&memcg->kmem, nr_pages, &counter)) {
+
+		/*
+		 * Enforce __GFP_NOFAIL allocation because callers are not
+		 * prepared to see failures and likely do not have any failure
+		 * handling code.
+		 */
+		if (gfp & __GFP_NOFAIL) {
+			page_counter_charge(&memcg->kmem, nr_pages);
+			return 0;
+		}
+		cancel_charge(memcg, nr_pages);
+		return -ENOMEM;
+	}
+
+	page->mem_cgroup = memcg;
+
+	return 0;
+}
+
+/**
+ * memcg_kmem_charge: charge a kmem page to the current memory cgroup
+ * @page: page to charge
+ * @gfp: reclaim mode
+ * @order: allocation order
+ *
+ * Returns 0 on success, an error code on failure.
+ */
+int memcg_kmem_charge(struct page *page, gfp_t gfp, int order)
+{
+	struct mem_cgroup *memcg;
+	int ret = 0;
+
+	if (mem_cgroup_disabled() || memcg_kmem_bypass())
+		return 0;
+
+	memcg = get_mem_cgroup_from_current();
+	if (!mem_cgroup_is_root(memcg)) {
+		ret = memcg_kmem_charge_memcg(page, gfp, order, memcg);
+		if (!ret)
+			__SetPageKmemcg(page);
+	}
+	css_put(&memcg->css);
+	return ret;
+}
+/**
+ * memcg_kmem_uncharge: uncharge a kmem page
+ * @page: page to uncharge
+ * @order: allocation order
+ */
+void memcg_kmem_uncharge(struct page *page, int order)
+{
+	struct mem_cgroup *memcg = page->mem_cgroup;
+	unsigned int nr_pages = 1 << order;
+
+	if (!memcg)
+		return;
+
+	VM_BUG_ON_PAGE(mem_cgroup_is_root(memcg), page);
+
+	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
+		page_counter_uncharge(&memcg->kmem, nr_pages);
+
+	page_counter_uncharge(&memcg->memory, nr_pages);
+	if (do_memsw_account())
+		page_counter_uncharge(&memcg->memsw, nr_pages);
+
+	page->mem_cgroup = NULL;
+
+	/* slab pages do not have PageKmemcg flag set */
+	if (PageKmemcg(page))
+		__ClearPageKmemcg(page);
+
+	css_put_many(&memcg->css, nr_pages);
+}
+#endif /* CONFIG_MEMCG_KMEM */
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+
+/*
+ * Because tail pages are not marked as "used", set it. We're under
+ * zone_lru_lock and migration entries setup in all page mappings.
+ */
+void mem_cgroup_split_huge_fixup(struct page *head)
+{
+	int i;
+
+	if (mem_cgroup_disabled())
+		return;
+
+	for (i = 1; i < HPAGE_PMD_NR; i++)
+		head[i].mem_cgroup = head->mem_cgroup;
+
+	__mod_memcg_state(head->mem_cgroup, MEMCG_RSS_HUGE, -HPAGE_PMD_NR);
+}
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+
+#ifdef CONFIG_MEMCG_SWAP
+/**
+ * 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
+ *
+ * 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 page_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)
+{
+	unsigned short old_id, new_id;
+
+	old_id = mem_cgroup_id(from);
+	new_id = mem_cgroup_id(to);
+
+	if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) {
+		mod_memcg_state(from, MEMCG_SWAP, -1);
+		mod_memcg_state(to, MEMCG_SWAP, 1);
+		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)
+{
+	return -EINVAL;
+}
+#endif
+
+static DEFINE_MUTEX(memcg_max_mutex);
+
+static int mem_cgroup_resize_max(struct mem_cgroup *memcg,
+				 unsigned long max, bool memsw)
+{
+	bool enlarge = false;
+	bool drained = false;
+	int ret;
+	bool limits_invariant;
+	struct page_counter *counter = memsw ? &memcg->memsw : &memcg->memory;
+
+	do {
+		if (signal_pending(current)) {
+			ret = -EINTR;
+			break;
+		}
+
+		mutex_lock(&memcg_max_mutex);
+		/*
+		 * Make sure that the new limit (memsw or memory limit) doesn't
+		 * break our basic invariant rule memory.max <= memsw.max.
+		 */
+		limits_invariant = memsw ? max >= memcg->memory.max :
+					   max <= memcg->memsw.max;
+		if (!limits_invariant) {
+			mutex_unlock(&memcg_max_mutex);
+			ret = -EINVAL;
+			break;
+		}
+		if (max > counter->max)
+			enlarge = true;
+		ret = page_counter_set_max(counter, max);
+		mutex_unlock(&memcg_max_mutex);
+
+		if (!ret)
+			break;
+
+		if (!drained) {
+			drain_all_stock(memcg);
+			drained = true;
+			continue;
+		}
+
+		if (!try_to_free_mem_cgroup_pages(memcg, 1,
+					GFP_KERNEL, !memsw)) {
+			ret = -EBUSY;
+			break;
+		}
+	} while (true);
+
+	if (!ret && enlarge)
+		memcg_oom_recover(memcg);
+
+	return ret;
+}
+
+unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
+					    gfp_t gfp_mask,
+					    unsigned long *total_scanned)
+{
+	unsigned long nr_reclaimed = 0;
+	struct mem_cgroup_per_node *mz, *next_mz = NULL;
+	unsigned long reclaimed;
+	int loop = 0;
+	struct mem_cgroup_tree_per_node *mctz;
+	unsigned long excess;
+	unsigned long nr_scanned;
+
+	if (order > 0)
+		return 0;
+
+	mctz = soft_limit_tree_node(pgdat->node_id);
+
+	/*
+	 * Do not even bother to check the largest node if the root
+	 * is empty. Do it lockless to prevent lock bouncing. Races
+	 * are acceptable as soft limit is best effort anyway.
+	 */
+	if (!mctz || RB_EMPTY_ROOT(&mctz->rb_root))
+		return 0;
+
+	/*
+	 * 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, pgdat,
+						    gfp_mask, &nr_scanned);
+		nr_reclaimed += reclaimed;
+		*total_scanned += nr_scanned;
+		spin_lock_irq(&mctz->lock);
+		__mem_cgroup_remove_exceeded(mz, mctz);
+
+		/*
+		 * 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)
+			next_mz = __mem_cgroup_largest_soft_limit_node(mctz);
+
+		excess = soft_limit_excess(mz->memcg);
+		/*
+		 * 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, mctz, excess);
+		spin_unlock_irq(&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;
+}
+
+/*
+ * Test whether @memcg has children, dead or alive.  Note that this
+ * function doesn't care whether @memcg has use_hierarchy enabled and
+ * returns %true if there are child csses according to the cgroup
+ * hierarchy.  Testing use_hierarchy is the caller's responsiblity.
+ */
+static inline bool memcg_has_children(struct mem_cgroup *memcg)
+{
+	bool ret;
+
+	rcu_read_lock();
+	ret = css_next_child(NULL, &memcg->css);
+	rcu_read_unlock();
+	return ret;
+}
+
+/*
+ * Reclaims as many pages from the given memcg as possible.
+ *
+ * Caller is responsible for holding css reference for memcg.
+ */
+static int mem_cgroup_force_empty(struct mem_cgroup *memcg)
+{
+	int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
+
+	/* we call try-to-free pages for make this cgroup empty */
+	lru_add_drain_all();
+
+	drain_all_stock(memcg);
+
+	/* try to free all pages in this cgroup */
+	while (nr_retries && page_counter_read(&memcg->memory)) {
+		int progress;
+
+		if (signal_pending(current))
+			return -EINTR;
+
+		progress = try_to_free_mem_cgroup_pages(memcg, 1,
+							GFP_KERNEL, true);
+		if (!progress) {
+			nr_retries--;
+			/* maybe some writeback is necessary */
+			congestion_wait(BLK_RW_ASYNC, HZ/10);
+		}
+
+	}
+
+	return 0;
+}
+
+static ssize_t mem_cgroup_force_empty_write(struct kernfs_open_file *of,
+					    char *buf, size_t nbytes,
+					    loff_t off)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+
+	if (mem_cgroup_is_root(memcg))
+		return -EINVAL;
+	return mem_cgroup_force_empty(memcg) ?: nbytes;
+}
+
+static u64 mem_cgroup_hierarchy_read(struct cgroup_subsys_state *css,
+				     struct cftype *cft)
+{
+	return mem_cgroup_from_css(css)->use_hierarchy;
+}
+
+static int mem_cgroup_hierarchy_write(struct cgroup_subsys_state *css,
+				      struct cftype *cft, u64 val)
+{
+	int retval = 0;
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+	struct mem_cgroup *parent_memcg = mem_cgroup_from_css(memcg->css.parent);
+
+	if (memcg->use_hierarchy == val)
+		return 0;
+
+	/*
+	 * 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 (!memcg_has_children(memcg))
+			memcg->use_hierarchy = val;
+		else
+			retval = -EBUSY;
+	} else
+		retval = -EINVAL;
+
+	return retval;
+}
+
+struct accumulated_stats {
+	unsigned long stat[MEMCG_NR_STAT];
+	unsigned long events[NR_VM_EVENT_ITEMS];
+	unsigned long lru_pages[NR_LRU_LISTS];
+	const unsigned int *stats_array;
+	const unsigned int *events_array;
+	int stats_size;
+	int events_size;
+};
+
+static void accumulate_memcg_tree(struct mem_cgroup *memcg,
+				  struct accumulated_stats *acc)
+{
+	struct mem_cgroup *mi;
+	int i;
+
+	for_each_mem_cgroup_tree(mi, memcg) {
+		for (i = 0; i < acc->stats_size; i++)
+			acc->stat[i] += memcg_page_state(mi,
+				acc->stats_array ? acc->stats_array[i] : i);
+
+		for (i = 0; i < acc->events_size; i++)
+			acc->events[i] += memcg_sum_events(mi,
+				acc->events_array ? acc->events_array[i] : i);
+
+		for (i = 0; i < NR_LRU_LISTS; i++)
+			acc->lru_pages[i] +=
+				mem_cgroup_nr_lru_pages(mi, BIT(i));
+	}
+}
+
+static unsigned long mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
+{
+	unsigned long val = 0;
+
+	if (mem_cgroup_is_root(memcg)) {
+		struct mem_cgroup *iter;
+
+		for_each_mem_cgroup_tree(iter, memcg) {
+			val += memcg_page_state(iter, MEMCG_CACHE);
+			val += memcg_page_state(iter, MEMCG_RSS);
+			if (swap)
+				val += memcg_page_state(iter, MEMCG_SWAP);
+		}
+	} else {
+		if (!swap)
+			val = page_counter_read(&memcg->memory);
+		else
+			val = page_counter_read(&memcg->memsw);
+	}
+	return val;
+}
+
+enum {
+	RES_USAGE,
+	RES_LIMIT,
+	RES_MAX_USAGE,
+	RES_FAILCNT,
+	RES_SOFT_LIMIT,
+};
+
+static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
+			       struct cftype *cft)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+	struct page_counter *counter;
+
+	switch (MEMFILE_TYPE(cft->private)) {
+	case _MEM:
+		counter = &memcg->memory;
+		break;
+	case _MEMSWAP:
+		counter = &memcg->memsw;
+		break;
+	case _KMEM:
+		counter = &memcg->kmem;
+		break;
+	case _TCP:
+		counter = &memcg->tcpmem;
+		break;
+	default:
+		BUG();
+	}
+
+	switch (MEMFILE_ATTR(cft->private)) {
+	case RES_USAGE:
+		if (counter == &memcg->memory)
+			return (u64)mem_cgroup_usage(memcg, false) * PAGE_SIZE;
+		if (counter == &memcg->memsw)
+			return (u64)mem_cgroup_usage(memcg, true) * PAGE_SIZE;
+		return (u64)page_counter_read(counter) * PAGE_SIZE;
+	case RES_LIMIT:
+		return (u64)counter->max * PAGE_SIZE;
+	case RES_MAX_USAGE:
+		return (u64)counter->watermark * PAGE_SIZE;
+	case RES_FAILCNT:
+		return counter->failcnt;
+	case RES_SOFT_LIMIT:
+		return (u64)memcg->soft_limit * PAGE_SIZE;
+	default:
+		BUG();
+	}
+}
+
+#ifdef CONFIG_MEMCG_KMEM
+static int memcg_online_kmem(struct mem_cgroup *memcg)
+{
+	int memcg_id;
+
+	if (cgroup_memory_nokmem)
+		return 0;
+
+	BUG_ON(memcg->kmemcg_id >= 0);
+	BUG_ON(memcg->kmem_state);
+
+	memcg_id = memcg_alloc_cache_id();
+	if (memcg_id < 0)
+		return memcg_id;
+
+	static_branch_inc(&memcg_kmem_enabled_key);
+	/*
+	 * A memory cgroup is considered kmem-online as soon as it gets
+	 * kmemcg_id. Setting the id after enabling static branching will
+	 * guarantee no one starts accounting before all call sites are
+	 * patched.
+	 */
+	memcg->kmemcg_id = memcg_id;
+	memcg->kmem_state = KMEM_ONLINE;
+	INIT_LIST_HEAD(&memcg->kmem_caches);
+
+	return 0;
+}
+
+static void memcg_offline_kmem(struct mem_cgroup *memcg)
+{
+	struct cgroup_subsys_state *css;
+	struct mem_cgroup *parent, *child;
+	int kmemcg_id;
+
+	if (memcg->kmem_state != KMEM_ONLINE)
+		return;
+	/*
+	 * Clear the online state before clearing memcg_caches array
+	 * entries. The slab_mutex in memcg_deactivate_kmem_caches()
+	 * guarantees that no cache will be created for this cgroup
+	 * after we are done (see memcg_create_kmem_cache()).
+	 */
+	memcg->kmem_state = KMEM_ALLOCATED;
+
+	memcg_deactivate_kmem_caches(memcg);
+
+	kmemcg_id = memcg->kmemcg_id;
+	BUG_ON(kmemcg_id < 0);
+
+	parent = parent_mem_cgroup(memcg);
+	if (!parent)
+		parent = root_mem_cgroup;
+
+	/*
+	 * Change kmemcg_id of this cgroup and all its descendants to the
+	 * parent's id, and then move all entries from this cgroup's list_lrus
+	 * to ones of the parent. After we have finished, all list_lrus
+	 * corresponding to this cgroup are guaranteed to remain empty. The
+	 * ordering is imposed by list_lru_node->lock taken by
+	 * memcg_drain_all_list_lrus().
+	 */
+	rcu_read_lock(); /* can be called from css_free w/o cgroup_mutex */
+	css_for_each_descendant_pre(css, &memcg->css) {
+		child = mem_cgroup_from_css(css);
+		BUG_ON(child->kmemcg_id != kmemcg_id);
+		child->kmemcg_id = parent->kmemcg_id;
+		if (!memcg->use_hierarchy)
+			break;
+	}
+	rcu_read_unlock();
+
+	memcg_drain_all_list_lrus(kmemcg_id, parent);
+
+	memcg_free_cache_id(kmemcg_id);
+}
+
+static void memcg_free_kmem(struct mem_cgroup *memcg)
+{
+	/* css_alloc() failed, offlining didn't happen */
+	if (unlikely(memcg->kmem_state == KMEM_ONLINE))
+		memcg_offline_kmem(memcg);
+
+	if (memcg->kmem_state == KMEM_ALLOCATED) {
+		memcg_destroy_kmem_caches(memcg);
+		static_branch_dec(&memcg_kmem_enabled_key);
+		WARN_ON(page_counter_read(&memcg->kmem));
+	}
+}
+#else
+static int memcg_online_kmem(struct mem_cgroup *memcg)
+{
+	return 0;
+}
+static void memcg_offline_kmem(struct mem_cgroup *memcg)
+{
+}
+static void memcg_free_kmem(struct mem_cgroup *memcg)
+{
+}
+#endif /* CONFIG_MEMCG_KMEM */
+
+static int memcg_update_kmem_max(struct mem_cgroup *memcg,
+				 unsigned long max)
+{
+	int ret;
+
+	mutex_lock(&memcg_max_mutex);
+	ret = page_counter_set_max(&memcg->kmem, max);
+	mutex_unlock(&memcg_max_mutex);
+	return ret;
+}
+
+static int memcg_update_tcp_max(struct mem_cgroup *memcg, unsigned long max)
+{
+	int ret;
+
+	mutex_lock(&memcg_max_mutex);
+
+	ret = page_counter_set_max(&memcg->tcpmem, max);
+	if (ret)
+		goto out;
+
+	if (!memcg->tcpmem_active) {
+		/*
+		 * The active flag needs to be written after the static_key
+		 * update. This is what guarantees that the socket activation
+		 * function is the last one to run. See mem_cgroup_sk_alloc()
+		 * for details, and note that we don't mark any socket as
+		 * belonging to this memcg until that flag is up.
+		 *
+		 * We need to do this, because static_keys will span multiple
+		 * sites, but we can't control their order. If we mark a socket
+		 * as accounted, but the accounting functions are not patched in
+		 * yet, we'll lose accounting.
+		 *
+		 * We never race with the readers in mem_cgroup_sk_alloc(),
+		 * because when this value change, the code to process it is not
+		 * patched in yet.
+		 */
+		static_branch_inc(&memcg_sockets_enabled_key);
+		memcg->tcpmem_active = true;
+	}
+out:
+	mutex_unlock(&memcg_max_mutex);
+	return ret;
+}
+
+/*
+ * The user of this function is...
+ * RES_LIMIT.
+ */
+static ssize_t mem_cgroup_write(struct kernfs_open_file *of,
+				char *buf, size_t nbytes, loff_t off)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+	unsigned long nr_pages;
+	int ret;
+
+	buf = strstrip(buf);
+	ret = page_counter_memparse(buf, "-1", &nr_pages);
+	if (ret)
+		return ret;
+
+	switch (MEMFILE_ATTR(of_cft(of)->private)) {
+	case RES_LIMIT:
+		if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */
+			ret = -EINVAL;
+			break;
+		}
+		switch (MEMFILE_TYPE(of_cft(of)->private)) {
+		case _MEM:
+			ret = mem_cgroup_resize_max(memcg, nr_pages, false);
+			break;
+		case _MEMSWAP:
+			ret = mem_cgroup_resize_max(memcg, nr_pages, true);
+			break;
+		case _KMEM:
+			ret = memcg_update_kmem_max(memcg, nr_pages);
+			break;
+		case _TCP:
+			ret = memcg_update_tcp_max(memcg, nr_pages);
+			break;
+		}
+		break;
+	case RES_SOFT_LIMIT:
+		memcg->soft_limit = nr_pages;
+		ret = 0;
+		break;
+	}
+	return ret ?: nbytes;
+}
+
+static ssize_t mem_cgroup_reset(struct kernfs_open_file *of, char *buf,
+				size_t nbytes, loff_t off)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+	struct page_counter *counter;
+
+	switch (MEMFILE_TYPE(of_cft(of)->private)) {
+	case _MEM:
+		counter = &memcg->memory;
+		break;
+	case _MEMSWAP:
+		counter = &memcg->memsw;
+		break;
+	case _KMEM:
+		counter = &memcg->kmem;
+		break;
+	case _TCP:
+		counter = &memcg->tcpmem;
+		break;
+	default:
+		BUG();
+	}
+
+	switch (MEMFILE_ATTR(of_cft(of)->private)) {
+	case RES_MAX_USAGE:
+		page_counter_reset_watermark(counter);
+		break;
+	case RES_FAILCNT:
+		counter->failcnt = 0;
+		break;
+	default:
+		BUG();
+	}
+
+	return nbytes;
+}
+
+static u64 mem_cgroup_move_charge_read(struct cgroup_subsys_state *css,
+					struct cftype *cft)
+{
+	return mem_cgroup_from_css(css)->move_charge_at_immigrate;
+}
+
+#ifdef CONFIG_MMU
+static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css,
+					struct cftype *cft, u64 val)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+
+	if (val & ~MOVE_MASK)
+		return -EINVAL;
+
+	/*
+	 * No kind of locking is needed in here, because ->can_attach() will
+	 * check this value once in the beginning of the process, and then carry
+	 * on with stale data. This means that changes to this value will only
+	 * affect task migrations starting after the change.
+	 */
+	memcg->move_charge_at_immigrate = val;
+	return 0;
+}
+#else
+static int mem_cgroup_move_charge_write(struct cgroup_subsys_state *css,
+					struct cftype *cft, u64 val)
+{
+	return -ENOSYS;
+}
+#endif
+
+#ifdef CONFIG_NUMA
+static int memcg_numa_stat_show(struct seq_file *m, void *v)
+{
+	struct numa_stat {
+		const char *name;
+		unsigned int lru_mask;
+	};
+
+	static const struct numa_stat stats[] = {
+		{ "total", LRU_ALL },
+		{ "file", LRU_ALL_FILE },
+		{ "anon", LRU_ALL_ANON },
+		{ "unevictable", BIT(LRU_UNEVICTABLE) },
+	};
+	const struct numa_stat *stat;
+	int nid;
+	unsigned long nr;
+	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+
+	for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) {
+		nr = mem_cgroup_nr_lru_pages(memcg, stat->lru_mask);
+		seq_printf(m, "%s=%lu", stat->name, nr);
+		for_each_node_state(nid, N_MEMORY) {
+			nr = mem_cgroup_node_nr_lru_pages(memcg, nid,
+							  stat->lru_mask);
+			seq_printf(m, " N%d=%lu", nid, nr);
+		}
+		seq_putc(m, '\n');
+	}
+
+	for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) {
+		struct mem_cgroup *iter;
+
+		nr = 0;
+		for_each_mem_cgroup_tree(iter, memcg)
+			nr += mem_cgroup_nr_lru_pages(iter, stat->lru_mask);
+		seq_printf(m, "hierarchical_%s=%lu", stat->name, nr);
+		for_each_node_state(nid, N_MEMORY) {
+			nr = 0;
+			for_each_mem_cgroup_tree(iter, memcg)
+				nr += mem_cgroup_node_nr_lru_pages(
+					iter, nid, stat->lru_mask);
+			seq_printf(m, " N%d=%lu", nid, nr);
+		}
+		seq_putc(m, '\n');
+	}
+
+	return 0;
+}
+#endif /* CONFIG_NUMA */
+
+/* Universal VM events cgroup1 shows, original sort order */
+static const unsigned int memcg1_events[] = {
+	PGPGIN,
+	PGPGOUT,
+	PGFAULT,
+	PGMAJFAULT,
+};
+
+static const char *const memcg1_event_names[] = {
+	"pgpgin",
+	"pgpgout",
+	"pgfault",
+	"pgmajfault",
+};
+
+static int memcg_stat_show(struct seq_file *m, void *v)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+	unsigned long memory, memsw;
+	struct mem_cgroup *mi;
+	unsigned int i;
+	struct accumulated_stats acc;
+
+	BUILD_BUG_ON(ARRAY_SIZE(memcg1_stat_names) != ARRAY_SIZE(memcg1_stats));
+	BUILD_BUG_ON(ARRAY_SIZE(mem_cgroup_lru_names) != NR_LRU_LISTS);
+
+	for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) {
+		if (memcg1_stats[i] == MEMCG_SWAP && !do_memsw_account())
+			continue;
+		seq_printf(m, "%s %lu\n", memcg1_stat_names[i],
+			   memcg_page_state(memcg, memcg1_stats[i]) *
+			   PAGE_SIZE);
+	}
+
+	for (i = 0; i < ARRAY_SIZE(memcg1_events); i++)
+		seq_printf(m, "%s %lu\n", memcg1_event_names[i],
+			   memcg_sum_events(memcg, memcg1_events[i]));
+
+	for (i = 0; i < NR_LRU_LISTS; i++)
+		seq_printf(m, "%s %lu\n", mem_cgroup_lru_names[i],
+			   mem_cgroup_nr_lru_pages(memcg, BIT(i)) * PAGE_SIZE);
+
+	/* Hierarchical information */
+	memory = memsw = PAGE_COUNTER_MAX;
+	for (mi = memcg; mi; mi = parent_mem_cgroup(mi)) {
+		memory = min(memory, mi->memory.max);
+		memsw = min(memsw, mi->memsw.max);
+	}
+	seq_printf(m, "hierarchical_memory_limit %llu\n",
+		   (u64)memory * PAGE_SIZE);
+	if (do_memsw_account())
+		seq_printf(m, "hierarchical_memsw_limit %llu\n",
+			   (u64)memsw * PAGE_SIZE);
+
+	memset(&acc, 0, sizeof(acc));
+	acc.stats_size = ARRAY_SIZE(memcg1_stats);
+	acc.stats_array = memcg1_stats;
+	acc.events_size = ARRAY_SIZE(memcg1_events);
+	acc.events_array = memcg1_events;
+	accumulate_memcg_tree(memcg, &acc);
+
+	for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) {
+		if (memcg1_stats[i] == MEMCG_SWAP && !do_memsw_account())
+			continue;
+		seq_printf(m, "total_%s %llu\n", memcg1_stat_names[i],
+			   (u64)acc.stat[i] * PAGE_SIZE);
+	}
+
+	for (i = 0; i < ARRAY_SIZE(memcg1_events); i++)
+		seq_printf(m, "total_%s %llu\n", memcg1_event_names[i],
+			   (u64)acc.events[i]);
+
+	for (i = 0; i < NR_LRU_LISTS; i++)
+		seq_printf(m, "total_%s %llu\n", mem_cgroup_lru_names[i],
+			   (u64)acc.lru_pages[i] * PAGE_SIZE);
+
+#ifdef CONFIG_DEBUG_VM
+	{
+		pg_data_t *pgdat;
+		struct mem_cgroup_per_node *mz;
+		struct zone_reclaim_stat *rstat;
+		unsigned long recent_rotated[2] = {0, 0};
+		unsigned long recent_scanned[2] = {0, 0};
+
+		for_each_online_pgdat(pgdat) {
+			mz = mem_cgroup_nodeinfo(memcg, pgdat->node_id);
+			rstat = &mz->lruvec.reclaim_stat;
+
+			recent_rotated[0] += rstat->recent_rotated[0];
+			recent_rotated[1] += rstat->recent_rotated[1];
+			recent_scanned[0] += rstat->recent_scanned[0];
+			recent_scanned[1] += rstat->recent_scanned[1];
+		}
+		seq_printf(m, "recent_rotated_anon %lu\n", recent_rotated[0]);
+		seq_printf(m, "recent_rotated_file %lu\n", recent_rotated[1]);
+		seq_printf(m, "recent_scanned_anon %lu\n", recent_scanned[0]);
+		seq_printf(m, "recent_scanned_file %lu\n", recent_scanned[1]);
+	}
+#endif
+
+	return 0;
+}
+
+static u64 mem_cgroup_swappiness_read(struct cgroup_subsys_state *css,
+				      struct cftype *cft)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+
+	return mem_cgroup_swappiness(memcg);
+}
+
+static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css,
+				       struct cftype *cft, u64 val)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+
+	if (val > 100)
+		return -EINVAL;
+
+	if (css->parent)
+		memcg->swappiness = val;
+	else
+		vm_swappiness = val;
+
+	return 0;
+}
+
+static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
+{
+	struct mem_cgroup_threshold_ary *t;
+	unsigned long 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 or equal to 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_memsw_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;
+
+	spin_lock(&memcg_oom_lock);
+
+	list_for_each_entry(ev, &memcg->oom_notify, list)
+		eventfd_signal(ev->eventfd, 1);
+
+	spin_unlock(&memcg_oom_lock);
+	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 mem_cgroup *memcg,
+	struct eventfd_ctx *eventfd, const char *args, enum res_type type)
+{
+	struct mem_cgroup_thresholds *thresholds;
+	struct mem_cgroup_threshold_ary *new;
+	unsigned long threshold;
+	unsigned long usage;
+	int i, size, ret;
+
+	ret = page_counter_memparse(args, "-1", &threshold);
+	if (ret)
+		return ret;
+
+	mutex_lock(&memcg->thresholds_lock);
+
+	if (type == _MEM) {
+		thresholds = &memcg->thresholds;
+		usage = mem_cgroup_usage(memcg, false);
+	} else if (type == _MEMSWAP) {
+		thresholds = &memcg->memsw_thresholds;
+		usage = mem_cgroup_usage(memcg, true);
+	} else
+		BUG();
+
+	/* 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;
+		} else
+			break;
+	}
+
+	/* 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 int mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
+	struct eventfd_ctx *eventfd, const char *args)
+{
+	return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEM);
+}
+
+static int memsw_cgroup_usage_register_event(struct mem_cgroup *memcg,
+	struct eventfd_ctx *eventfd, const char *args)
+{
+	return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEMSWAP);
+}
+
+static void __mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
+	struct eventfd_ctx *eventfd, enum res_type type)
+{
+	struct mem_cgroup_thresholds *thresholds;
+	struct mem_cgroup_threshold_ary *new;
+	unsigned long usage;
+	int i, j, size, entries;
+
+	mutex_lock(&memcg->thresholds_lock);
+
+	if (type == _MEM) {
+		thresholds = &memcg->thresholds;
+		usage = mem_cgroup_usage(memcg, false);
+	} else if (type == _MEMSWAP) {
+		thresholds = &memcg->memsw_thresholds;
+		usage = mem_cgroup_usage(memcg, true);
+	} else
+		BUG();
+
+	if (!thresholds->primary)
+		goto unlock;
+
+	/* Check if a threshold crossed before removing */
+	__mem_cgroup_threshold(memcg, type == _MEMSWAP);
+
+	/* Calculate new number of threshold */
+	size = entries = 0;
+	for (i = 0; i < thresholds->primary->size; i++) {
+		if (thresholds->primary->entries[i].eventfd != eventfd)
+			size++;
+		else
+			entries++;
+	}
+
+	new = thresholds->spare;
+
+	/* If no items related to eventfd have been cleared, nothing to do */
+	if (!entries)
+		goto unlock;
+
+	/* 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;
+
+	rcu_assign_pointer(thresholds->primary, new);
+
+	/* To be sure that nobody uses thresholds */
+	synchronize_rcu();
+
+	/* If all events are unregistered, free the spare array */
+	if (!new) {
+		kfree(thresholds->spare);
+		thresholds->spare = NULL;
+	}
+unlock:
+	mutex_unlock(&memcg->thresholds_lock);
+}
+
+static void mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
+	struct eventfd_ctx *eventfd)
+{
+	return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEM);
+}
+
+static void memsw_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
+	struct eventfd_ctx *eventfd)
+{
+	return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEMSWAP);
+}
+
+static int mem_cgroup_oom_register_event(struct mem_cgroup *memcg,
+	struct eventfd_ctx *eventfd, const char *args)
+{
+	struct mem_cgroup_eventfd_list *event;
+
+	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 (memcg->under_oom)
+		eventfd_signal(eventfd, 1);
+	spin_unlock(&memcg_oom_lock);
+
+	return 0;
+}
+
+static void mem_cgroup_oom_unregister_event(struct mem_cgroup *memcg,
+	struct eventfd_ctx *eventfd)
+{
+	struct mem_cgroup_eventfd_list *ev, *tmp;
+
+	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 seq_file *sf, void *v)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(sf));
+
+	seq_printf(sf, "oom_kill_disable %d\n", memcg->oom_kill_disable);
+	seq_printf(sf, "under_oom %d\n", (bool)memcg->under_oom);
+	seq_printf(sf, "oom_kill %lu\n",
+		   atomic_long_read(&memcg->memory_events[MEMCG_OOM_KILL]));
+	return 0;
+}
+
+static int mem_cgroup_oom_control_write(struct cgroup_subsys_state *css,
+	struct cftype *cft, u64 val)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+
+	/* cannot set to root cgroup and only 0 and 1 are allowed */
+	if (!css->parent || !((val == 0) || (val == 1)))
+		return -EINVAL;
+
+	memcg->oom_kill_disable = val;
+	if (!val)
+		memcg_oom_recover(memcg);
+
+	return 0;
+}
+
+#ifdef CONFIG_CGROUP_WRITEBACK
+
+static int memcg_wb_domain_init(struct mem_cgroup *memcg, gfp_t gfp)
+{
+	return wb_domain_init(&memcg->cgwb_domain, gfp);
+}
+
+static void memcg_wb_domain_exit(struct mem_cgroup *memcg)
+{
+	wb_domain_exit(&memcg->cgwb_domain);
+}
+
+static void memcg_wb_domain_size_changed(struct mem_cgroup *memcg)
+{
+	wb_domain_size_changed(&memcg->cgwb_domain);
+}
+
+struct wb_domain *mem_cgroup_wb_domain(struct bdi_writeback *wb)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(wb->memcg_css);
+
+	if (!memcg->css.parent)
+		return NULL;
+
+	return &memcg->cgwb_domain;
+}
+
+/*
+ * idx can be of type enum memcg_stat_item or node_stat_item.
+ * Keep in sync with memcg_exact_page().
+ */
+static unsigned long memcg_exact_page_state(struct mem_cgroup *memcg, int idx)
+{
+	long x = atomic_long_read(&memcg->stat[idx]);
+	int cpu;
+
+	for_each_online_cpu(cpu)
+		x += per_cpu_ptr(memcg->stat_cpu, cpu)->count[idx];
+	if (x < 0)
+		x = 0;
+	return x;
+}
+
+/**
+ * mem_cgroup_wb_stats - retrieve writeback related stats from its memcg
+ * @wb: bdi_writeback in question
+ * @pfilepages: out parameter for number of file pages
+ * @pheadroom: out parameter for number of allocatable pages according to memcg
+ * @pdirty: out parameter for number of dirty pages
+ * @pwriteback: out parameter for number of pages under writeback
+ *
+ * Determine the numbers of file, headroom, dirty, and writeback pages in
+ * @wb's memcg.  File, dirty and writeback are self-explanatory.  Headroom
+ * is a bit more involved.
+ *
+ * A memcg's headroom is "min(max, high) - used".  In the hierarchy, the
+ * headroom is calculated as the lowest headroom of itself and the
+ * ancestors.  Note that this doesn't consider the actual amount of
+ * available memory in the system.  The caller should further cap
+ * *@pheadroom accordingly.
+ */
+void mem_cgroup_wb_stats(struct bdi_writeback *wb, unsigned long *pfilepages,
+			 unsigned long *pheadroom, unsigned long *pdirty,
+			 unsigned long *pwriteback)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(wb->memcg_css);
+	struct mem_cgroup *parent;
+
+	*pdirty = memcg_exact_page_state(memcg, NR_FILE_DIRTY);
+
+	/* this should eventually include NR_UNSTABLE_NFS */
+	*pwriteback = memcg_exact_page_state(memcg, NR_WRITEBACK);
+	*pfilepages = mem_cgroup_nr_lru_pages(memcg, (1 << LRU_INACTIVE_FILE) |
+						     (1 << LRU_ACTIVE_FILE));
+	*pheadroom = PAGE_COUNTER_MAX;
+
+	while ((parent = parent_mem_cgroup(memcg))) {
+		unsigned long ceiling = min(memcg->memory.max, memcg->high);
+		unsigned long used = page_counter_read(&memcg->memory);
+
+		*pheadroom = min(*pheadroom, ceiling - min(ceiling, used));
+		memcg = parent;
+	}
+}
+
+#else	/* CONFIG_CGROUP_WRITEBACK */
+
+static int memcg_wb_domain_init(struct mem_cgroup *memcg, gfp_t gfp)
+{
+	return 0;
+}
+
+static void memcg_wb_domain_exit(struct mem_cgroup *memcg)
+{
+}
+
+static void memcg_wb_domain_size_changed(struct mem_cgroup *memcg)
+{
+}
+
+#endif	/* CONFIG_CGROUP_WRITEBACK */
+
+/*
+ * DO NOT USE IN NEW FILES.
+ *
+ * "cgroup.event_control" implementation.
+ *
+ * This is way over-engineered.  It tries to support fully configurable
+ * events for each user.  Such level of flexibility is completely
+ * unnecessary especially in the light of the planned unified hierarchy.
+ *
+ * Please deprecate this and replace with something simpler if at all
+ * possible.
+ */
+
+/*
+ * Unregister event and free resources.
+ *
+ * Gets called from workqueue.
+ */
+static void memcg_event_remove(struct work_struct *work)
+{
+	struct mem_cgroup_event *event =
+		container_of(work, struct mem_cgroup_event, remove);
+	struct mem_cgroup *memcg = event->memcg;
+
+	remove_wait_queue(event->wqh, &event->wait);
+
+	event->unregister_event(memcg, event->eventfd);
+
+	/* Notify userspace the event is going away. */
+	eventfd_signal(event->eventfd, 1);
+
+	eventfd_ctx_put(event->eventfd);
+	kfree(event);
+	css_put(&memcg->css);
+}
+
+/*
+ * Gets called on EPOLLHUP on eventfd when user closes it.
+ *
+ * Called with wqh->lock held and interrupts disabled.
+ */
+static int memcg_event_wake(wait_queue_entry_t *wait, unsigned mode,
+			    int sync, void *key)
+{
+	struct mem_cgroup_event *event =
+		container_of(wait, struct mem_cgroup_event, wait);
+	struct mem_cgroup *memcg = event->memcg;
+	__poll_t flags = key_to_poll(key);
+
+	if (flags & EPOLLHUP) {
+		/*
+		 * If the event has been detached at cgroup removal, we
+		 * can simply return knowing the other side will cleanup
+		 * for us.
+		 *
+		 * We can't race against event freeing since the other
+		 * side will require wqh->lock via remove_wait_queue(),
+		 * which we hold.
+		 */
+		spin_lock(&memcg->event_list_lock);
+		if (!list_empty(&event->list)) {
+			list_del_init(&event->list);
+			/*
+			 * We are in atomic context, but cgroup_event_remove()
+			 * may sleep, so we have to call it in workqueue.
+			 */
+			schedule_work(&event->remove);
+		}
+		spin_unlock(&memcg->event_list_lock);
+	}
+
+	return 0;
+}
+
+static void memcg_event_ptable_queue_proc(struct file *file,
+		wait_queue_head_t *wqh, poll_table *pt)
+{
+	struct mem_cgroup_event *event =
+		container_of(pt, struct mem_cgroup_event, pt);
+
+	event->wqh = wqh;
+	add_wait_queue(wqh, &event->wait);
+}
+
+/*
+ * DO NOT USE IN NEW FILES.
+ *
+ * Parse input and register new cgroup event handler.
+ *
+ * Input must be in format '<event_fd> <control_fd> <args>'.
+ * Interpretation of args is defined by control file implementation.
+ */
+static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
+					 char *buf, size_t nbytes, loff_t off)
+{
+	struct cgroup_subsys_state *css = of_css(of);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+	struct mem_cgroup_event *event;
+	struct cgroup_subsys_state *cfile_css;
+	unsigned int efd, cfd;
+	struct fd efile;
+	struct fd cfile;
+	const char *name;
+	char *endp;
+	int ret;
+
+	buf = strstrip(buf);
+
+	efd = simple_strtoul(buf, &endp, 10);
+	if (*endp != ' ')
+		return -EINVAL;
+	buf = endp + 1;
+
+	cfd = simple_strtoul(buf, &endp, 10);
+	if ((*endp != ' ') && (*endp != '\0'))
+		return -EINVAL;
+	buf = endp + 1;
+
+	event = kzalloc(sizeof(*event), GFP_KERNEL);
+	if (!event)
+		return -ENOMEM;
+
+	event->memcg = memcg;
+	INIT_LIST_HEAD(&event->list);
+	init_poll_funcptr(&event->pt, memcg_event_ptable_queue_proc);
+	init_waitqueue_func_entry(&event->wait, memcg_event_wake);
+	INIT_WORK(&event->remove, memcg_event_remove);
+
+	efile = fdget(efd);
+	if (!efile.file) {
+		ret = -EBADF;
+		goto out_kfree;
+	}
+
+	event->eventfd = eventfd_ctx_fileget(efile.file);
+	if (IS_ERR(event->eventfd)) {
+		ret = PTR_ERR(event->eventfd);
+		goto out_put_efile;
+	}
+
+	cfile = fdget(cfd);
+	if (!cfile.file) {
+		ret = -EBADF;
+		goto out_put_eventfd;
+	}
+
+	/* the process need read permission on control file */
+	/* AV: shouldn't we check that it's been opened for read instead? */
+	ret = inode_permission(file_inode(cfile.file), MAY_READ);
+	if (ret < 0)
+		goto out_put_cfile;
+
+	/*
+	 * Determine the event callbacks and set them in @event.  This used
+	 * to be done via struct cftype but cgroup core no longer knows
+	 * about these events.  The following is crude but the whole thing
+	 * is for compatibility anyway.
+	 *
+	 * DO NOT ADD NEW FILES.
+	 */
+	name = cfile.file->f_path.dentry->d_name.name;
+
+	if (!strcmp(name, "memory.usage_in_bytes")) {
+		event->register_event = mem_cgroup_usage_register_event;
+		event->unregister_event = mem_cgroup_usage_unregister_event;
+	} else if (!strcmp(name, "memory.oom_control")) {
+		event->register_event = mem_cgroup_oom_register_event;
+		event->unregister_event = mem_cgroup_oom_unregister_event;
+	} else if (!strcmp(name, "memory.pressure_level")) {
+		event->register_event = vmpressure_register_event;
+		event->unregister_event = vmpressure_unregister_event;
+	} else if (!strcmp(name, "memory.memsw.usage_in_bytes")) {
+		event->register_event = memsw_cgroup_usage_register_event;
+		event->unregister_event = memsw_cgroup_usage_unregister_event;
+	} else {
+		ret = -EINVAL;
+		goto out_put_cfile;
+	}
+
+	/*
+	 * Verify @cfile should belong to @css.  Also, remaining events are
+	 * automatically removed on cgroup destruction but the removal is
+	 * asynchronous, so take an extra ref on @css.
+	 */
+	cfile_css = css_tryget_online_from_dir(cfile.file->f_path.dentry->d_parent,
+					       &memory_cgrp_subsys);
+	ret = -EINVAL;
+	if (IS_ERR(cfile_css))
+		goto out_put_cfile;
+	if (cfile_css != css) {
+		css_put(cfile_css);
+		goto out_put_cfile;
+	}
+
+	ret = event->register_event(memcg, event->eventfd, buf);
+	if (ret)
+		goto out_put_css;
+
+	vfs_poll(efile.file, &event->pt);
+
+	spin_lock(&memcg->event_list_lock);
+	list_add(&event->list, &memcg->event_list);
+	spin_unlock(&memcg->event_list_lock);
+
+	fdput(cfile);
+	fdput(efile);
+
+	return nbytes;
+
+out_put_css:
+	css_put(css);
+out_put_cfile:
+	fdput(cfile);
+out_put_eventfd:
+	eventfd_ctx_put(event->eventfd);
+out_put_efile:
+	fdput(efile);
+out_kfree:
+	kfree(event);
+
+	return ret;
+}
+
+static struct cftype mem_cgroup_legacy_files[] = {
+	{
+		.name = "usage_in_bytes",
+		.private = MEMFILE_PRIVATE(_MEM, RES_USAGE),
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "max_usage_in_bytes",
+		.private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE),
+		.write = mem_cgroup_reset,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "limit_in_bytes",
+		.private = MEMFILE_PRIVATE(_MEM, RES_LIMIT),
+		.write = mem_cgroup_write,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "soft_limit_in_bytes",
+		.private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT),
+		.write = mem_cgroup_write,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "failcnt",
+		.private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT),
+		.write = mem_cgroup_reset,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "stat",
+		.seq_show = memcg_stat_show,
+	},
+	{
+		.name = "force_empty",
+		.write = mem_cgroup_force_empty_write,
+	},
+	{
+		.name = "use_hierarchy",
+		.write_u64 = mem_cgroup_hierarchy_write,
+		.read_u64 = mem_cgroup_hierarchy_read,
+	},
+	{
+		.name = "cgroup.event_control",		/* XXX: for compat */
+		.write = memcg_write_event_control,
+		.flags = CFTYPE_NO_PREFIX | CFTYPE_WORLD_WRITABLE,
+	},
+	{
+		.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",
+		.seq_show = mem_cgroup_oom_control_read,
+		.write_u64 = mem_cgroup_oom_control_write,
+		.private = MEMFILE_PRIVATE(_OOM_TYPE, OOM_CONTROL),
+	},
+	{
+		.name = "pressure_level",
+	},
+#ifdef CONFIG_NUMA
+	{
+		.name = "numa_stat",
+		.seq_show = memcg_numa_stat_show,
+	},
+#endif
+	{
+		.name = "kmem.limit_in_bytes",
+		.private = MEMFILE_PRIVATE(_KMEM, RES_LIMIT),
+		.write = mem_cgroup_write,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "kmem.usage_in_bytes",
+		.private = MEMFILE_PRIVATE(_KMEM, RES_USAGE),
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "kmem.failcnt",
+		.private = MEMFILE_PRIVATE(_KMEM, RES_FAILCNT),
+		.write = mem_cgroup_reset,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "kmem.max_usage_in_bytes",
+		.private = MEMFILE_PRIVATE(_KMEM, RES_MAX_USAGE),
+		.write = mem_cgroup_reset,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+#if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG)
+	{
+		.name = "kmem.slabinfo",
+		.seq_start = memcg_slab_start,
+		.seq_next = memcg_slab_next,
+		.seq_stop = memcg_slab_stop,
+		.seq_show = memcg_slab_show,
+	},
+#endif
+	{
+		.name = "kmem.tcp.limit_in_bytes",
+		.private = MEMFILE_PRIVATE(_TCP, RES_LIMIT),
+		.write = mem_cgroup_write,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "kmem.tcp.usage_in_bytes",
+		.private = MEMFILE_PRIVATE(_TCP, RES_USAGE),
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "kmem.tcp.failcnt",
+		.private = MEMFILE_PRIVATE(_TCP, RES_FAILCNT),
+		.write = mem_cgroup_reset,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "kmem.tcp.max_usage_in_bytes",
+		.private = MEMFILE_PRIVATE(_TCP, RES_MAX_USAGE),
+		.write = mem_cgroup_reset,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{ },	/* terminate */
+};
+
+/*
+ * Private memory cgroup IDR
+ *
+ * Swap-out records and page cache shadow entries need to store memcg
+ * references in constrained space, so we maintain an ID space that is
+ * limited to 16 bit (MEM_CGROUP_ID_MAX), limiting the total number of
+ * memory-controlled cgroups to 64k.
+ *
+ * However, there usually are many references to the oflline CSS after
+ * the cgroup has been destroyed, such as page cache or reclaimable
+ * slab objects, that don't need to hang on to the ID. We want to keep
+ * those dead CSS from occupying IDs, or we might quickly exhaust the
+ * relatively small ID space and prevent the creation of new cgroups
+ * even when there are much fewer than 64k cgroups - possibly none.
+ *
+ * Maintain a private 16-bit ID space for memcg, and allow the ID to
+ * be freed and recycled when it's no longer needed, which is usually
+ * when the CSS is offlined.
+ *
+ * The only exception to that are records of swapped out tmpfs/shmem
+ * pages that need to be attributed to live ancestors on swapin. But
+ * those references are manageable from userspace.
+ */
+
+static DEFINE_IDR(mem_cgroup_idr);
+
+static void mem_cgroup_id_remove(struct mem_cgroup *memcg)
+{
+	if (memcg->id.id > 0) {
+		idr_remove(&mem_cgroup_idr, memcg->id.id);
+		memcg->id.id = 0;
+	}
+}
+
+static void mem_cgroup_id_get_many(struct mem_cgroup *memcg, unsigned int n)
+{
+	VM_BUG_ON(atomic_read(&memcg->id.ref) <= 0);
+	atomic_add(n, &memcg->id.ref);
+}
+
+static void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n)
+{
+	VM_BUG_ON(atomic_read(&memcg->id.ref) < n);
+	if (atomic_sub_and_test(n, &memcg->id.ref)) {
+		mem_cgroup_id_remove(memcg);
+
+		/* Memcg ID pins CSS */
+		css_put(&memcg->css);
+	}
+}
+
+static inline void mem_cgroup_id_get(struct mem_cgroup *memcg)
+{
+	mem_cgroup_id_get_many(memcg, 1);
+}
+
+static inline void mem_cgroup_id_put(struct mem_cgroup *memcg)
+{
+	mem_cgroup_id_put_many(memcg, 1);
+}
+
+/**
+ * mem_cgroup_from_id - look up a memcg from a memcg id
+ * @id: the memcg id to look up
+ *
+ * Caller must hold rcu_read_lock().
+ */
+struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
+{
+	WARN_ON_ONCE(!rcu_read_lock_held());
+	return idr_find(&mem_cgroup_idr, id);
+}
+
+static int alloc_mem_cgroup_per_node_info(struct mem_cgroup *memcg, int node)
+{
+	struct mem_cgroup_per_node *pn;
+	int 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;
+
+	pn->lruvec_stat_cpu = alloc_percpu(struct lruvec_stat);
+	if (!pn->lruvec_stat_cpu) {
+		kfree(pn);
+		return 1;
+	}
+
+	lruvec_init(&pn->lruvec);
+	pn->usage_in_excess = 0;
+	pn->on_tree = false;
+	pn->memcg = memcg;
+
+	memcg->nodeinfo[node] = pn;
+	return 0;
+}
+
+static void free_mem_cgroup_per_node_info(struct mem_cgroup *memcg, int node)
+{
+	struct mem_cgroup_per_node *pn = memcg->nodeinfo[node];
+
+	if (!pn)
+		return;
+
+	free_percpu(pn->lruvec_stat_cpu);
+	kfree(pn);
+}
+
+static void __mem_cgroup_free(struct mem_cgroup *memcg)
+{
+	int node;
+
+	for_each_node(node)
+		free_mem_cgroup_per_node_info(memcg, node);
+	free_percpu(memcg->stat_cpu);
+	kfree(memcg);
+}
+
+static void mem_cgroup_free(struct mem_cgroup *memcg)
+{
+	memcg_wb_domain_exit(memcg);
+	__mem_cgroup_free(memcg);
+}
+
+static struct mem_cgroup *mem_cgroup_alloc(void)
+{
+	struct mem_cgroup *memcg;
+	size_t size;
+	int node;
+
+	size = sizeof(struct mem_cgroup);
+	size += nr_node_ids * sizeof(struct mem_cgroup_per_node *);
+
+	memcg = kzalloc(size, GFP_KERNEL);
+	if (!memcg)
+		return NULL;
+
+	memcg->id.id = idr_alloc(&mem_cgroup_idr, NULL,
+				 1, MEM_CGROUP_ID_MAX,
+				 GFP_KERNEL);
+	if (memcg->id.id < 0)
+		goto fail;
+
+	memcg->stat_cpu = alloc_percpu(struct mem_cgroup_stat_cpu);
+	if (!memcg->stat_cpu)
+		goto fail;
+
+	for_each_node(node)
+		if (alloc_mem_cgroup_per_node_info(memcg, node))
+			goto fail;
+
+	if (memcg_wb_domain_init(memcg, GFP_KERNEL))
+		goto fail;
+
+	INIT_WORK(&memcg->high_work, high_work_func);
+	memcg->last_scanned_node = MAX_NUMNODES;
+	INIT_LIST_HEAD(&memcg->oom_notify);
+	mutex_init(&memcg->thresholds_lock);
+	spin_lock_init(&memcg->move_lock);
+	vmpressure_init(&memcg->vmpressure);
+	INIT_LIST_HEAD(&memcg->event_list);
+	spin_lock_init(&memcg->event_list_lock);
+	memcg->socket_pressure = jiffies;
+#ifdef CONFIG_MEMCG_KMEM
+	memcg->kmemcg_id = -1;
+#endif
+#ifdef CONFIG_CGROUP_WRITEBACK
+	INIT_LIST_HEAD(&memcg->cgwb_list);
+#endif
+	idr_replace(&mem_cgroup_idr, memcg, memcg->id.id);
+	return memcg;
+fail:
+	mem_cgroup_id_remove(memcg);
+	__mem_cgroup_free(memcg);
+	return NULL;
+}
+
+static struct cgroup_subsys_state * __ref
+mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
+{
+	struct mem_cgroup *parent = mem_cgroup_from_css(parent_css);
+	struct mem_cgroup *memcg;
+	long error = -ENOMEM;
+
+	memcg = mem_cgroup_alloc();
+	if (!memcg)
+		return ERR_PTR(error);
+
+	memcg->high = PAGE_COUNTER_MAX;
+	memcg->soft_limit = PAGE_COUNTER_MAX;
+	if (parent) {
+		memcg->swappiness = mem_cgroup_swappiness(parent);
+		memcg->oom_kill_disable = parent->oom_kill_disable;
+	}
+	if (parent && parent->use_hierarchy) {
+		memcg->use_hierarchy = true;
+		page_counter_init(&memcg->memory, &parent->memory);
+		page_counter_init(&memcg->swap, &parent->swap);
+		page_counter_init(&memcg->memsw, &parent->memsw);
+		page_counter_init(&memcg->kmem, &parent->kmem);
+		page_counter_init(&memcg->tcpmem, &parent->tcpmem);
+	} else {
+		page_counter_init(&memcg->memory, NULL);
+		page_counter_init(&memcg->swap, NULL);
+		page_counter_init(&memcg->memsw, NULL);
+		page_counter_init(&memcg->kmem, NULL);
+		page_counter_init(&memcg->tcpmem, NULL);
+		/*
+		 * Deeper hierachy with use_hierarchy == false doesn't make
+		 * much sense so let cgroup subsystem know about this
+		 * unfortunate state in our controller.
+		 */
+		if (parent != root_mem_cgroup)
+			memory_cgrp_subsys.broken_hierarchy = true;
+	}
+
+	/* The following stuff does not apply to the root */
+	if (!parent) {
+		root_mem_cgroup = memcg;
+		return &memcg->css;
+	}
+
+	error = memcg_online_kmem(memcg);
+	if (error)
+		goto fail;
+
+	if (cgroup_subsys_on_dfl(memory_cgrp_subsys) && !cgroup_memory_nosocket)
+		static_branch_inc(&memcg_sockets_enabled_key);
+
+	return &memcg->css;
+fail:
+	mem_cgroup_id_remove(memcg);
+	mem_cgroup_free(memcg);
+	return ERR_PTR(-ENOMEM);
+}
+
+static int mem_cgroup_css_online(struct cgroup_subsys_state *css)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+
+	/*
+	 * A memcg must be visible for memcg_expand_shrinker_maps()
+	 * by the time the maps are allocated. So, we allocate maps
+	 * here, when for_each_mem_cgroup() can't skip it.
+	 */
+	if (memcg_alloc_shrinker_maps(memcg)) {
+		mem_cgroup_id_remove(memcg);
+		return -ENOMEM;
+	}
+
+	/* Online state pins memcg ID, memcg ID pins CSS */
+	atomic_set(&memcg->id.ref, 1);
+	css_get(css);
+	return 0;
+}
+
+static void mem_cgroup_css_offline(struct cgroup_subsys_state *css)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+	struct mem_cgroup_event *event, *tmp;
+
+	/*
+	 * Unregister events and notify userspace.
+	 * Notify userspace about cgroup removing only after rmdir of cgroup
+	 * directory to avoid race between userspace and kernelspace.
+	 */
+	spin_lock(&memcg->event_list_lock);
+	list_for_each_entry_safe(event, tmp, &memcg->event_list, list) {
+		list_del_init(&event->list);
+		schedule_work(&event->remove);
+	}
+	spin_unlock(&memcg->event_list_lock);
+
+	page_counter_set_min(&memcg->memory, 0);
+	page_counter_set_low(&memcg->memory, 0);
+
+	memcg_offline_kmem(memcg);
+	wb_memcg_offline(memcg);
+
+	mem_cgroup_id_put(memcg);
+}
+
+static void mem_cgroup_css_released(struct cgroup_subsys_state *css)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+
+	invalidate_reclaim_iterators(memcg);
+}
+
+static void mem_cgroup_css_free(struct cgroup_subsys_state *css)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+
+	if (cgroup_subsys_on_dfl(memory_cgrp_subsys) && !cgroup_memory_nosocket)
+		static_branch_dec(&memcg_sockets_enabled_key);
+
+	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && memcg->tcpmem_active)
+		static_branch_dec(&memcg_sockets_enabled_key);
+
+	vmpressure_cleanup(&memcg->vmpressure);
+	cancel_work_sync(&memcg->high_work);
+	mem_cgroup_remove_from_trees(memcg);
+	memcg_free_shrinker_maps(memcg);
+	memcg_free_kmem(memcg);
+	mem_cgroup_free(memcg);
+}
+
+/**
+ * mem_cgroup_css_reset - reset the states of a mem_cgroup
+ * @css: the target css
+ *
+ * Reset the states of the mem_cgroup associated with @css.  This is
+ * invoked when the userland requests disabling on the default hierarchy
+ * but the memcg is pinned through dependency.  The memcg should stop
+ * applying policies and should revert to the vanilla state as it may be
+ * made visible again.
+ *
+ * The current implementation only resets the essential configurations.
+ * This needs to be expanded to cover all the visible parts.
+ */
+static void mem_cgroup_css_reset(struct cgroup_subsys_state *css)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+
+	page_counter_set_max(&memcg->memory, PAGE_COUNTER_MAX);
+	page_counter_set_max(&memcg->swap, PAGE_COUNTER_MAX);
+	page_counter_set_max(&memcg->memsw, PAGE_COUNTER_MAX);
+	page_counter_set_max(&memcg->kmem, PAGE_COUNTER_MAX);
+	page_counter_set_max(&memcg->tcpmem, PAGE_COUNTER_MAX);
+	page_counter_set_min(&memcg->memory, 0);
+	page_counter_set_low(&memcg->memory, 0);
+	memcg->high = PAGE_COUNTER_MAX;
+	memcg->soft_limit = PAGE_COUNTER_MAX;
+	memcg_wb_domain_size_changed(memcg);
+}
+
+#ifdef CONFIG_MMU
+/* Handlers for move charge at task migration. */
+static int mem_cgroup_do_precharge(unsigned long count)
+{
+	int ret;
+
+	/* Try a single bulk charge without reclaim first, kswapd may wake */
+	ret = try_charge(mc.to, GFP_KERNEL & ~__GFP_DIRECT_RECLAIM, count);
+	if (!ret) {
+		mc.precharge += count;
+		return ret;
+	}
+
+	/* Try charges one by one with reclaim, but do not retry */
+	while (count--) {
+		ret = try_charge(mc.to, GFP_KERNEL | __GFP_NORETRY, 1);
+		if (ret)
+			return ret;
+		mc.precharge++;
+		cond_resched();
+	}
+	return 0;
+}
+
+union mc_target {
+	struct page	*page;
+	swp_entry_t	ent;
+};
+
+enum mc_target_type {
+	MC_TARGET_NONE = 0,
+	MC_TARGET_PAGE,
+	MC_TARGET_SWAP,
+	MC_TARGET_DEVICE,
+};
+
+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, true);
+
+	if (!page || !page_mapped(page))
+		return NULL;
+	if (PageAnon(page)) {
+		if (!(mc.flags & MOVE_ANON))
+			return NULL;
+	} else {
+		if (!(mc.flags & MOVE_FILE))
+			return NULL;
+	}
+	if (!get_page_unless_zero(page))
+		return NULL;
+
+	return page;
+}
+
+#if defined(CONFIG_SWAP) || defined(CONFIG_DEVICE_PRIVATE)
+static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
+			pte_t ptent, swp_entry_t *entry)
+{
+	struct page *page = NULL;
+	swp_entry_t ent = pte_to_swp_entry(ptent);
+
+	if (!(mc.flags & MOVE_ANON))
+		return NULL;
+
+	/*
+	 * Handle MEMORY_DEVICE_PRIVATE which are ZONE_DEVICE page belonging to
+	 * a device and because they are not accessible by CPU they are store
+	 * as special swap entry in the CPU page table.
+	 */
+	if (is_device_private_entry(ent)) {
+		page = device_private_entry_to_page(ent);
+		/*
+		 * MEMORY_DEVICE_PRIVATE means ZONE_DEVICE page and which have
+		 * a refcount of 1 when free (unlike normal page)
+		 */
+		if (!page_ref_add_unless(page, 1, 1))
+			return NULL;
+		return page;
+	}
+
+	if (non_swap_entry(ent))
+		return NULL;
+
+	/*
+	 * Because lookup_swap_cache() updates some statistics counter,
+	 * we call find_get_page() with swapper_space directly.
+	 */
+	page = find_get_page(swap_address_space(ent), swp_offset(ent));
+	if (do_memsw_account())
+		entry->val = ent.val;
+
+	return page;
+}
+#else
+static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
+			pte_t ptent, swp_entry_t *entry)
+{
+	return NULL;
+}
+#endif
+
+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 address_space *mapping;
+	pgoff_t pgoff;
+
+	if (!vma->vm_file) /* anonymous vma */
+		return NULL;
+	if (!(mc.flags & MOVE_FILE))
+		return NULL;
+
+	mapping = vma->vm_file->f_mapping;
+	pgoff = linear_page_index(vma, addr);
+
+	/* page is moved even if it's not RSS of this task(page-faulted). */
+#ifdef CONFIG_SWAP
+	/* shmem/tmpfs may report page out on swap: account for that too. */
+	if (shmem_mapping(mapping)) {
+		page = find_get_entry(mapping, pgoff);
+		if (radix_tree_exceptional_entry(page)) {
+			swp_entry_t swp = radix_to_swp_entry(page);
+			if (do_memsw_account())
+				*entry = swp;
+			page = find_get_page(swap_address_space(swp),
+					     swp_offset(swp));
+		}
+	} else
+		page = find_get_page(mapping, pgoff);
+#else
+	page = find_get_page(mapping, pgoff);
+#endif
+	return page;
+}
+
+/**
+ * mem_cgroup_move_account - move account of the page
+ * @page: the page
+ * @compound: charge the page as compound or small page
+ * @from: mem_cgroup which the page is moved from.
+ * @to:	mem_cgroup which the page is moved to. @from != @to.
+ *
+ * The caller must make sure the page is not on LRU (isolate_page() is useful.)
+ *
+ * This function doesn't do "charge" to new cgroup and doesn't do "uncharge"
+ * from old cgroup.
+ */
+static int mem_cgroup_move_account(struct page *page,
+				   bool compound,
+				   struct mem_cgroup *from,
+				   struct mem_cgroup *to)
+{
+	unsigned long flags;
+	unsigned int nr_pages = compound ? hpage_nr_pages(page) : 1;
+	int ret;
+	bool anon;
+
+	VM_BUG_ON(from == to);
+	VM_BUG_ON_PAGE(PageLRU(page), page);
+	VM_BUG_ON(compound && !PageTransHuge(page));
+
+	/*
+	 * Prevent mem_cgroup_migrate() from looking at
+	 * page->mem_cgroup of its source page while we change it.
+	 */
+	ret = -EBUSY;
+	if (!trylock_page(page))
+		goto out;
+
+	ret = -EINVAL;
+	if (page->mem_cgroup != from)
+		goto out_unlock;
+
+	anon = PageAnon(page);
+
+	spin_lock_irqsave(&from->move_lock, flags);
+
+	if (!anon && page_mapped(page)) {
+		__mod_memcg_state(from, NR_FILE_MAPPED, -nr_pages);
+		__mod_memcg_state(to, NR_FILE_MAPPED, nr_pages);
+	}
+
+	/*
+	 * move_lock grabbed above and caller set from->moving_account, so
+	 * mod_memcg_page_state will serialize updates to PageDirty.
+	 * So mapping should be stable for dirty pages.
+	 */
+	if (!anon && PageDirty(page)) {
+		struct address_space *mapping = page_mapping(page);
+
+		if (mapping_cap_account_dirty(mapping)) {
+			__mod_memcg_state(from, NR_FILE_DIRTY, -nr_pages);
+			__mod_memcg_state(to, NR_FILE_DIRTY, nr_pages);
+		}
+	}
+
+	if (PageWriteback(page)) {
+		__mod_memcg_state(from, NR_WRITEBACK, -nr_pages);
+		__mod_memcg_state(to, NR_WRITEBACK, nr_pages);
+	}
+
+	/*
+	 * It is safe to change page->mem_cgroup here because the page
+	 * is referenced, charged, and isolated - we can't race with
+	 * uncharging, charging, migration, or LRU putback.
+	 */
+
+	/* caller should have done css_get */
+	page->mem_cgroup = to;
+	spin_unlock_irqrestore(&from->move_lock, flags);
+
+	ret = 0;
+
+	local_irq_disable();
+	mem_cgroup_charge_statistics(to, page, compound, nr_pages);
+	memcg_check_events(to, page);
+	mem_cgroup_charge_statistics(from, page, compound, -nr_pages);
+	memcg_check_events(from, page);
+	local_irq_enable();
+out_unlock:
+	unlock_page(page);
+out:
+	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.
+ *   3(MC_TARGET_DEVICE): like MC_TARGET_PAGE  but page is MEMORY_DEVICE_PUBLIC
+ *     or MEMORY_DEVICE_PRIVATE (so ZONE_DEVICE page and thus not on the lru).
+ *     For now we such page is charge like a regular page would be as for all
+ *     intent and purposes it is just special memory taking the place of a
+ *     regular page.
+ *
+ *     See Documentations/vm/hmm.txt and include/linux/hmm.h
+ *
+ * Called with pte lock held.
+ */
+
+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;
+	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, ptent, &ent);
+	else if (pte_none(ptent))
+		page = mc_handle_file_pte(vma, addr, ptent, &ent);
+
+	if (!page && !ent.val)
+		return ret;
+	if (page) {
+		/*
+		 * Do only loose check w/o serialization.
+		 * mem_cgroup_move_account() checks the page is valid or
+		 * not under LRU exclusion.
+		 */
+		if (page->mem_cgroup == mc.from) {
+			ret = MC_TARGET_PAGE;
+			if (is_device_private_page(page) ||
+			    is_device_public_page(page))
+				ret = MC_TARGET_DEVICE;
+			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.
+	 * But we cannot move a tail-page in a THP.
+	 */
+	if (ent.val && !ret && (!page || !PageTransCompound(page)) &&
+	    mem_cgroup_id(mc.from) == lookup_swap_cgroup_id(ent)) {
+		ret = MC_TARGET_SWAP;
+		if (target)
+			target->ent = ent;
+	}
+	return ret;
+}
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+/*
+ * We don't consider PMD mapped 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;
+	enum mc_target_type ret = MC_TARGET_NONE;
+
+	if (unlikely(is_swap_pmd(pmd))) {
+		VM_BUG_ON(thp_migration_supported() &&
+				  !is_pmd_migration_entry(pmd));
+		return ret;
+	}
+	page = pmd_page(pmd);
+	VM_BUG_ON_PAGE(!page || !PageHead(page), page);
+	if (!(mc.flags & MOVE_ANON))
+		return ret;
+	if (page->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->vma;
+	pte_t *pte;
+	spinlock_t *ptl;
+
+	ptl = pmd_trans_huge_lock(pmd, vma);
+	if (ptl) {
+		/*
+		 * Note their can not be MC_TARGET_DEVICE for now as we do not
+		 * support transparent huge page with MEMORY_DEVICE_PUBLIC or
+		 * MEMORY_DEVICE_PRIVATE but this might change.
+		 */
+		if (get_mctgt_type_thp(vma, addr, *pmd, NULL) == MC_TARGET_PAGE)
+			mc.precharge += HPAGE_PMD_NR;
+		spin_unlock(ptl);
+		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 mm_walk mem_cgroup_count_precharge_walk = {
+		.pmd_entry = mem_cgroup_count_precharge_pte_range,
+		.mm = mm,
+	};
+	down_read(&mm->mmap_sem);
+	walk_page_range(0, mm->highest_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) {
+		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) {
+		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))
+			page_counter_uncharge(&mc.from->memsw, mc.moved_swap);
+
+		mem_cgroup_id_put_many(mc.from, mc.moved_swap);
+
+		/*
+		 * we charged both to->memory and to->memsw, so we
+		 * should uncharge to->memory.
+		 */
+		if (!mem_cgroup_is_root(mc.to))
+			page_counter_uncharge(&mc.to->memory, mc.moved_swap);
+
+		css_put_many(&mc.to->css, mc.moved_swap);
+
+		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 mm_struct *mm = mc.mm;
+
+	/*
+	 * 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;
+	mc.mm = NULL;
+	spin_unlock(&mc.lock);
+
+	mmput(mm);
+}
+
+static int mem_cgroup_can_attach(struct cgroup_taskset *tset)
+{
+	struct cgroup_subsys_state *css;
+	struct mem_cgroup *memcg = NULL; /* unneeded init to make gcc happy */
+	struct mem_cgroup *from;
+	struct task_struct *leader, *p;
+	struct mm_struct *mm;
+	unsigned long move_flags;
+	int ret = 0;
+
+	/* charge immigration isn't supported on the default hierarchy */
+	if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
+		return 0;
+
+	/*
+	 * Multi-process migrations only happen on the default hierarchy
+	 * where charge immigration is not used.  Perform charge
+	 * immigration if @tset contains a leader and whine if there are
+	 * multiple.
+	 */
+	p = NULL;
+	cgroup_taskset_for_each_leader(leader, css, tset) {
+		WARN_ON_ONCE(p);
+		p = leader;
+		memcg = mem_cgroup_from_css(css);
+	}
+	if (!p)
+		return 0;
+
+	/*
+	 * We are now commited to this value whatever it is. Changes in this
+	 * tunable will only affect upcoming migrations, not the current one.
+	 * So we need to save it, and keep it going.
+	 */
+	move_flags = READ_ONCE(memcg->move_charge_at_immigrate);
+	if (!move_flags)
+		return 0;
+
+	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);
+
+		spin_lock(&mc.lock);
+		mc.mm = mm;
+		mc.from = from;
+		mc.to = memcg;
+		mc.flags = move_flags;
+		spin_unlock(&mc.lock);
+		/* We set mc.moving_task later */
+
+		ret = mem_cgroup_precharge_mc(mm);
+		if (ret)
+			mem_cgroup_clear_mc();
+	} else {
+		mmput(mm);
+	}
+	return ret;
+}
+
+static void mem_cgroup_cancel_attach(struct cgroup_taskset *tset)
+{
+	if (mc.to)
+		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->vma;
+	pte_t *pte;
+	spinlock_t *ptl;
+	enum mc_target_type target_type;
+	union mc_target target;
+	struct page *page;
+
+	ptl = pmd_trans_huge_lock(pmd, vma);
+	if (ptl) {
+		if (mc.precharge < HPAGE_PMD_NR) {
+			spin_unlock(ptl);
+			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)) {
+				if (!mem_cgroup_move_account(page, true,
+							     mc.from, mc.to)) {
+					mc.precharge -= HPAGE_PMD_NR;
+					mc.moved_charge += HPAGE_PMD_NR;
+				}
+				putback_lru_page(page);
+			}
+			put_page(page);
+		} else if (target_type == MC_TARGET_DEVICE) {
+			page = target.page;
+			if (!mem_cgroup_move_account(page, true,
+						     mc.from, mc.to)) {
+				mc.precharge -= HPAGE_PMD_NR;
+				mc.moved_charge += HPAGE_PMD_NR;
+			}
+			put_page(page);
+		}
+		spin_unlock(ptl);
+		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++);
+		bool device = false;
+		swp_entry_t ent;
+
+		if (!mc.precharge)
+			break;
+
+		switch (get_mctgt_type(vma, addr, ptent, &target)) {
+		case MC_TARGET_DEVICE:
+			device = true;
+			/* fall through */
+		case MC_TARGET_PAGE:
+			page = target.page;
+			/*
+			 * We can have a part of the split pmd here. Moving it
+			 * can be done but it would be too convoluted so simply
+			 * ignore such a partial THP and keep it in original
+			 * memcg. There should be somebody mapping the head.
+			 */
+			if (PageTransCompound(page))
+				goto put;
+			if (!device && isolate_lru_page(page))
+				goto put;
+			if (!mem_cgroup_move_account(page, false,
+						mc.from, mc.to)) {
+				mc.precharge--;
+				/* we uncharge from mc.from later. */
+				mc.moved_charge++;
+			}
+			if (!device)
+				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)) {
+				mc.precharge--;
+				mem_cgroup_id_get_many(mc.to, 1);
+				/* we fixup other 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(void)
+{
+	struct mm_walk mem_cgroup_move_charge_walk = {
+		.pmd_entry = mem_cgroup_move_charge_pte_range,
+		.mm = mc.mm,
+	};
+
+	lru_add_drain_all();
+	/*
+	 * Signal lock_page_memcg() to take the memcg's move_lock
+	 * while we're moving its pages to another memcg. Then wait
+	 * for already started RCU-only updates to finish.
+	 */
+	atomic_inc(&mc.from->moving_account);
+	synchronize_rcu();
+retry:
+	if (unlikely(!down_read_trylock(&mc.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;
+	}
+	/*
+	 * When we have consumed all precharges and failed in doing
+	 * additional charge, the page walk just aborts.
+	 */
+	walk_page_range(0, mc.mm->highest_vm_end, &mem_cgroup_move_charge_walk);
+
+	up_read(&mc.mm->mmap_sem);
+	atomic_dec(&mc.from->moving_account);
+}
+
+static void mem_cgroup_move_task(void)
+{
+	if (mc.to) {
+		mem_cgroup_move_charge();
+		mem_cgroup_clear_mc();
+	}
+}
+#else	/* !CONFIG_MMU */
+static int mem_cgroup_can_attach(struct cgroup_taskset *tset)
+{
+	return 0;
+}
+static void mem_cgroup_cancel_attach(struct cgroup_taskset *tset)
+{
+}
+static void mem_cgroup_move_task(void)
+{
+}
+#endif
+
+/*
+ * Cgroup retains root cgroups across [un]mount cycles making it necessary
+ * to verify whether we're attached to the default hierarchy on each mount
+ * attempt.
+ */
+static void mem_cgroup_bind(struct cgroup_subsys_state *root_css)
+{
+	/*
+	 * use_hierarchy is forced on the default hierarchy.  cgroup core
+	 * guarantees that @root doesn't have any children, so turning it
+	 * on for the root memcg is enough.
+	 */
+	if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
+		root_mem_cgroup->use_hierarchy = true;
+	else
+		root_mem_cgroup->use_hierarchy = false;
+}
+
+static u64 memory_current_read(struct cgroup_subsys_state *css,
+			       struct cftype *cft)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+
+	return (u64)page_counter_read(&memcg->memory) * PAGE_SIZE;
+}
+
+static int memory_min_show(struct seq_file *m, void *v)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+	unsigned long min = READ_ONCE(memcg->memory.min);
+
+	if (min == PAGE_COUNTER_MAX)
+		seq_puts(m, "max\n");
+	else
+		seq_printf(m, "%llu\n", (u64)min * PAGE_SIZE);
+
+	return 0;
+}
+
+static ssize_t memory_min_write(struct kernfs_open_file *of,
+				char *buf, size_t nbytes, loff_t off)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+	unsigned long min;
+	int err;
+
+	buf = strstrip(buf);
+	err = page_counter_memparse(buf, "max", &min);
+	if (err)
+		return err;
+
+	page_counter_set_min(&memcg->memory, min);
+
+	return nbytes;
+}
+
+static int memory_low_show(struct seq_file *m, void *v)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+	unsigned long low = READ_ONCE(memcg->memory.low);
+
+	if (low == PAGE_COUNTER_MAX)
+		seq_puts(m, "max\n");
+	else
+		seq_printf(m, "%llu\n", (u64)low * PAGE_SIZE);
+
+	return 0;
+}
+
+static ssize_t memory_low_write(struct kernfs_open_file *of,
+				char *buf, size_t nbytes, loff_t off)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+	unsigned long low;
+	int err;
+
+	buf = strstrip(buf);
+	err = page_counter_memparse(buf, "max", &low);
+	if (err)
+		return err;
+
+	page_counter_set_low(&memcg->memory, low);
+
+	return nbytes;
+}
+
+static int memory_high_show(struct seq_file *m, void *v)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+	unsigned long high = READ_ONCE(memcg->high);
+
+	if (high == PAGE_COUNTER_MAX)
+		seq_puts(m, "max\n");
+	else
+		seq_printf(m, "%llu\n", (u64)high * PAGE_SIZE);
+
+	return 0;
+}
+
+static ssize_t memory_high_write(struct kernfs_open_file *of,
+				 char *buf, size_t nbytes, loff_t off)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+	unsigned long nr_pages;
+	unsigned long high;
+	int err;
+
+	buf = strstrip(buf);
+	err = page_counter_memparse(buf, "max", &high);
+	if (err)
+		return err;
+
+	memcg->high = high;
+
+	nr_pages = page_counter_read(&memcg->memory);
+	if (nr_pages > high)
+		try_to_free_mem_cgroup_pages(memcg, nr_pages - high,
+					     GFP_KERNEL, true);
+
+	memcg_wb_domain_size_changed(memcg);
+	return nbytes;
+}
+
+static int memory_max_show(struct seq_file *m, void *v)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+	unsigned long max = READ_ONCE(memcg->memory.max);
+
+	if (max == PAGE_COUNTER_MAX)
+		seq_puts(m, "max\n");
+	else
+		seq_printf(m, "%llu\n", (u64)max * PAGE_SIZE);
+
+	return 0;
+}
+
+static ssize_t memory_max_write(struct kernfs_open_file *of,
+				char *buf, size_t nbytes, loff_t off)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+	unsigned int nr_reclaims = MEM_CGROUP_RECLAIM_RETRIES;
+	bool drained = false;
+	unsigned long max;
+	int err;
+
+	buf = strstrip(buf);
+	err = page_counter_memparse(buf, "max", &max);
+	if (err)
+		return err;
+
+	xchg(&memcg->memory.max, max);
+
+	for (;;) {
+		unsigned long nr_pages = page_counter_read(&memcg->memory);
+
+		if (nr_pages <= max)
+			break;
+
+		if (signal_pending(current)) {
+			err = -EINTR;
+			break;
+		}
+
+		if (!drained) {
+			drain_all_stock(memcg);
+			drained = true;
+			continue;
+		}
+
+		if (nr_reclaims) {
+			if (!try_to_free_mem_cgroup_pages(memcg, nr_pages - max,
+							  GFP_KERNEL, true))
+				nr_reclaims--;
+			continue;
+		}
+
+		memcg_memory_event(memcg, MEMCG_OOM);
+		if (!mem_cgroup_out_of_memory(memcg, GFP_KERNEL, 0))
+			break;
+	}
+
+	memcg_wb_domain_size_changed(memcg);
+	return nbytes;
+}
+
+static int memory_events_show(struct seq_file *m, void *v)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+
+	seq_printf(m, "low %lu\n",
+		   atomic_long_read(&memcg->memory_events[MEMCG_LOW]));
+	seq_printf(m, "high %lu\n",
+		   atomic_long_read(&memcg->memory_events[MEMCG_HIGH]));
+	seq_printf(m, "max %lu\n",
+		   atomic_long_read(&memcg->memory_events[MEMCG_MAX]));
+	seq_printf(m, "oom %lu\n",
+		   atomic_long_read(&memcg->memory_events[MEMCG_OOM]));
+	seq_printf(m, "oom_kill %lu\n",
+		   atomic_long_read(&memcg->memory_events[MEMCG_OOM_KILL]));
+
+	return 0;
+}
+
+static int memory_stat_show(struct seq_file *m, void *v)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+	struct accumulated_stats acc;
+	int i;
+
+	/*
+	 * Provide statistics on the state of the memory subsystem as
+	 * well as cumulative event counters that show past behavior.
+	 *
+	 * This list is ordered following a combination of these gradients:
+	 * 1) generic big picture -> specifics and details
+	 * 2) reflecting userspace activity -> reflecting kernel heuristics
+	 *
+	 * Current memory state:
+	 */
+
+	memset(&acc, 0, sizeof(acc));
+	acc.stats_size = MEMCG_NR_STAT;
+	acc.events_size = NR_VM_EVENT_ITEMS;
+	accumulate_memcg_tree(memcg, &acc);
+
+	seq_printf(m, "anon %llu\n",
+		   (u64)acc.stat[MEMCG_RSS] * PAGE_SIZE);
+	seq_printf(m, "file %llu\n",
+		   (u64)acc.stat[MEMCG_CACHE] * PAGE_SIZE);
+	seq_printf(m, "kernel_stack %llu\n",
+		   (u64)acc.stat[MEMCG_KERNEL_STACK_KB] * 1024);
+	seq_printf(m, "slab %llu\n",
+		   (u64)(acc.stat[NR_SLAB_RECLAIMABLE] +
+			 acc.stat[NR_SLAB_UNRECLAIMABLE]) * PAGE_SIZE);
+	seq_printf(m, "sock %llu\n",
+		   (u64)acc.stat[MEMCG_SOCK] * PAGE_SIZE);
+
+	seq_printf(m, "shmem %llu\n",
+		   (u64)acc.stat[NR_SHMEM] * PAGE_SIZE);
+	seq_printf(m, "file_mapped %llu\n",
+		   (u64)acc.stat[NR_FILE_MAPPED] * PAGE_SIZE);
+	seq_printf(m, "file_dirty %llu\n",
+		   (u64)acc.stat[NR_FILE_DIRTY] * PAGE_SIZE);
+	seq_printf(m, "file_writeback %llu\n",
+		   (u64)acc.stat[NR_WRITEBACK] * PAGE_SIZE);
+
+	for (i = 0; i < NR_LRU_LISTS; i++)
+		seq_printf(m, "%s %llu\n", mem_cgroup_lru_names[i],
+			   (u64)acc.lru_pages[i] * PAGE_SIZE);
+
+	seq_printf(m, "slab_reclaimable %llu\n",
+		   (u64)acc.stat[NR_SLAB_RECLAIMABLE] * PAGE_SIZE);
+	seq_printf(m, "slab_unreclaimable %llu\n",
+		   (u64)acc.stat[NR_SLAB_UNRECLAIMABLE] * PAGE_SIZE);
+
+	/* Accumulated memory events */
+
+	seq_printf(m, "pgfault %lu\n", acc.events[PGFAULT]);
+	seq_printf(m, "pgmajfault %lu\n", acc.events[PGMAJFAULT]);
+
+	seq_printf(m, "pgrefill %lu\n", acc.events[PGREFILL]);
+	seq_printf(m, "pgscan %lu\n", acc.events[PGSCAN_KSWAPD] +
+		   acc.events[PGSCAN_DIRECT]);
+	seq_printf(m, "pgsteal %lu\n", acc.events[PGSTEAL_KSWAPD] +
+		   acc.events[PGSTEAL_DIRECT]);
+	seq_printf(m, "pgactivate %lu\n", acc.events[PGACTIVATE]);
+	seq_printf(m, "pgdeactivate %lu\n", acc.events[PGDEACTIVATE]);
+	seq_printf(m, "pglazyfree %lu\n", acc.events[PGLAZYFREE]);
+	seq_printf(m, "pglazyfreed %lu\n", acc.events[PGLAZYFREED]);
+
+	seq_printf(m, "workingset_refault %lu\n",
+		   acc.stat[WORKINGSET_REFAULT]);
+	seq_printf(m, "workingset_activate %lu\n",
+		   acc.stat[WORKINGSET_ACTIVATE]);
+	seq_printf(m, "workingset_nodereclaim %lu\n",
+		   acc.stat[WORKINGSET_NODERECLAIM]);
+
+	return 0;
+}
+
+static int memory_oom_group_show(struct seq_file *m, void *v)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+
+	seq_printf(m, "%d\n", memcg->oom_group);
+
+	return 0;
+}
+
+static ssize_t memory_oom_group_write(struct kernfs_open_file *of,
+				      char *buf, size_t nbytes, loff_t off)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+	int ret, oom_group;
+
+	buf = strstrip(buf);
+	if (!buf)
+		return -EINVAL;
+
+	ret = kstrtoint(buf, 0, &oom_group);
+	if (ret)
+		return ret;
+
+	if (oom_group != 0 && oom_group != 1)
+		return -EINVAL;
+
+	memcg->oom_group = oom_group;
+
+	return nbytes;
+}
+
+static struct cftype memory_files[] = {
+	{
+		.name = "current",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.read_u64 = memory_current_read,
+	},
+	{
+		.name = "min",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.seq_show = memory_min_show,
+		.write = memory_min_write,
+	},
+	{
+		.name = "low",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.seq_show = memory_low_show,
+		.write = memory_low_write,
+	},
+	{
+		.name = "high",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.seq_show = memory_high_show,
+		.write = memory_high_write,
+	},
+	{
+		.name = "max",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.seq_show = memory_max_show,
+		.write = memory_max_write,
+	},
+	{
+		.name = "events",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.file_offset = offsetof(struct mem_cgroup, events_file),
+		.seq_show = memory_events_show,
+	},
+	{
+		.name = "stat",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.seq_show = memory_stat_show,
+	},
+	{
+		.name = "oom.group",
+		.flags = CFTYPE_NOT_ON_ROOT | CFTYPE_NS_DELEGATABLE,
+		.seq_show = memory_oom_group_show,
+		.write = memory_oom_group_write,
+	},
+	{ }	/* terminate */
+};
+
+struct cgroup_subsys memory_cgrp_subsys = {
+	.css_alloc = mem_cgroup_css_alloc,
+	.css_online = mem_cgroup_css_online,
+	.css_offline = mem_cgroup_css_offline,
+	.css_released = mem_cgroup_css_released,
+	.css_free = mem_cgroup_css_free,
+	.css_reset = mem_cgroup_css_reset,
+	.can_attach = mem_cgroup_can_attach,
+	.cancel_attach = mem_cgroup_cancel_attach,
+	.post_attach = mem_cgroup_move_task,
+	.bind = mem_cgroup_bind,
+	.dfl_cftypes = memory_files,
+	.legacy_cftypes = mem_cgroup_legacy_files,
+	.early_init = 0,
+};
+
+/**
+ * mem_cgroup_protected - check if memory consumption is in the normal range
+ * @root: the top ancestor of the sub-tree being checked
+ * @memcg: the memory cgroup to check
+ *
+ * WARNING: This function is not stateless! It can only be used as part
+ *          of a top-down tree iteration, not for isolated queries.
+ *
+ * Returns one of the following:
+ *   MEMCG_PROT_NONE: cgroup memory is not protected
+ *   MEMCG_PROT_LOW: cgroup memory is protected as long there is
+ *     an unprotected supply of reclaimable memory from other cgroups.
+ *   MEMCG_PROT_MIN: cgroup memory is protected
+ *
+ * @root is exclusive; it is never protected when looked at directly
+ *
+ * To provide a proper hierarchical behavior, effective memory.min/low values
+ * are used. Below is the description of how effective memory.low is calculated.
+ * Effective memory.min values is calculated in the same way.
+ *
+ * Effective memory.low is always equal or less than the original memory.low.
+ * If there is no memory.low overcommittment (which is always true for
+ * top-level memory cgroups), these two values are equal.
+ * Otherwise, it's a part of parent's effective memory.low,
+ * calculated as a cgroup's memory.low usage divided by sum of sibling's
+ * memory.low usages, where memory.low usage is the size of actually
+ * protected memory.
+ *
+ *                                             low_usage
+ * elow = min( memory.low, parent->elow * ------------------ ),
+ *                                        siblings_low_usage
+ *
+ *             | memory.current, if memory.current < memory.low
+ * low_usage = |
+	       | 0, otherwise.
+ *
+ *
+ * Such definition of the effective memory.low provides the expected
+ * hierarchical behavior: parent's memory.low value is limiting
+ * children, unprotected memory is reclaimed first and cgroups,
+ * which are not using their guarantee do not affect actual memory
+ * distribution.
+ *
+ * For example, if there are memcgs A, A/B, A/C, A/D and A/E:
+ *
+ *     A      A/memory.low = 2G, A/memory.current = 6G
+ *    //\\
+ *   BC  DE   B/memory.low = 3G  B/memory.current = 2G
+ *            C/memory.low = 1G  C/memory.current = 2G
+ *            D/memory.low = 0   D/memory.current = 2G
+ *            E/memory.low = 10G E/memory.current = 0
+ *
+ * and the memory pressure is applied, the following memory distribution
+ * is expected (approximately):
+ *
+ *     A/memory.current = 2G
+ *
+ *     B/memory.current = 1.3G
+ *     C/memory.current = 0.6G
+ *     D/memory.current = 0
+ *     E/memory.current = 0
+ *
+ * These calculations require constant tracking of the actual low usages
+ * (see propagate_protected_usage()), as well as recursive calculation of
+ * effective memory.low values. But as we do call mem_cgroup_protected()
+ * path for each memory cgroup top-down from the reclaim,
+ * it's possible to optimize this part, and save calculated elow
+ * for next usage. This part is intentionally racy, but it's ok,
+ * as memory.low is a best-effort mechanism.
+ */
+enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root,
+						struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *parent;
+	unsigned long emin, parent_emin;
+	unsigned long elow, parent_elow;
+	unsigned long usage;
+
+	if (mem_cgroup_disabled())
+		return MEMCG_PROT_NONE;
+
+	if (!root)
+		root = root_mem_cgroup;
+	if (memcg == root)
+		return MEMCG_PROT_NONE;
+
+	usage = page_counter_read(&memcg->memory);
+	if (!usage)
+		return MEMCG_PROT_NONE;
+
+	emin = memcg->memory.min;
+	elow = memcg->memory.low;
+
+	parent = parent_mem_cgroup(memcg);
+	/* No parent means a non-hierarchical mode on v1 memcg */
+	if (!parent)
+		return MEMCG_PROT_NONE;
+
+	if (parent == root)
+		goto exit;
+
+	parent_emin = READ_ONCE(parent->memory.emin);
+	emin = min(emin, parent_emin);
+	if (emin && parent_emin) {
+		unsigned long min_usage, siblings_min_usage;
+
+		min_usage = min(usage, memcg->memory.min);
+		siblings_min_usage = atomic_long_read(
+			&parent->memory.children_min_usage);
+
+		if (min_usage && siblings_min_usage)
+			emin = min(emin, parent_emin * min_usage /
+				   siblings_min_usage);
+	}
+
+	parent_elow = READ_ONCE(parent->memory.elow);
+	elow = min(elow, parent_elow);
+	if (elow && parent_elow) {
+		unsigned long low_usage, siblings_low_usage;
+
+		low_usage = min(usage, memcg->memory.low);
+		siblings_low_usage = atomic_long_read(
+			&parent->memory.children_low_usage);
+
+		if (low_usage && siblings_low_usage)
+			elow = min(elow, parent_elow * low_usage /
+				   siblings_low_usage);
+	}
+
+exit:
+	memcg->memory.emin = emin;
+	memcg->memory.elow = elow;
+
+	if (usage <= emin)
+		return MEMCG_PROT_MIN;
+	else if (usage <= elow)
+		return MEMCG_PROT_LOW;
+	else
+		return MEMCG_PROT_NONE;
+}
+
+/**
+ * mem_cgroup_try_charge - try charging a page
+ * @page: page to charge
+ * @mm: mm context of the victim
+ * @gfp_mask: reclaim mode
+ * @memcgp: charged memcg return
+ * @compound: charge the page as compound or small page
+ *
+ * Try to charge @page to the memcg that @mm belongs to, reclaiming
+ * pages according to @gfp_mask if necessary.
+ *
+ * Returns 0 on success, with *@memcgp pointing to the charged memcg.
+ * Otherwise, an error code is returned.
+ *
+ * After page->mapping has been set up, the caller must finalize the
+ * charge with mem_cgroup_commit_charge().  Or abort the transaction
+ * with mem_cgroup_cancel_charge() in case page instantiation fails.
+ */
+int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm,
+			  gfp_t gfp_mask, struct mem_cgroup **memcgp,
+			  bool compound)
+{
+	struct mem_cgroup *memcg = NULL;
+	unsigned int nr_pages = compound ? hpage_nr_pages(page) : 1;
+	int ret = 0;
+
+	if (mem_cgroup_disabled())
+		goto out;
+
+	if (PageSwapCache(page)) {
+		/*
+		 * Every swap fault against a single page tries to charge the
+		 * page, bail as early as possible.  shmem_unuse() encounters
+		 * already charged pages, too.  The USED bit is protected by
+		 * the page lock, which serializes swap cache removal, which
+		 * in turn serializes uncharging.
+		 */
+		VM_BUG_ON_PAGE(!PageLocked(page), page);
+		if (compound_head(page)->mem_cgroup)
+			goto out;
+
+		if (do_swap_account) {
+			swp_entry_t ent = { .val = page_private(page), };
+			unsigned short id = lookup_swap_cgroup_id(ent);
+
+			rcu_read_lock();
+			memcg = mem_cgroup_from_id(id);
+			if (memcg && !css_tryget_online(&memcg->css))
+				memcg = NULL;
+			rcu_read_unlock();
+		}
+	}
+
+	if (!memcg)
+		memcg = get_mem_cgroup_from_mm(mm);
+
+	ret = try_charge(memcg, gfp_mask, nr_pages);
+
+	css_put(&memcg->css);
+out:
+	*memcgp = memcg;
+	return ret;
+}
+
+int mem_cgroup_try_charge_delay(struct page *page, struct mm_struct *mm,
+			  gfp_t gfp_mask, struct mem_cgroup **memcgp,
+			  bool compound)
+{
+	struct mem_cgroup *memcg;
+	int ret;
+
+	ret = mem_cgroup_try_charge(page, mm, gfp_mask, memcgp, compound);
+	memcg = *memcgp;
+	mem_cgroup_throttle_swaprate(memcg, page_to_nid(page), gfp_mask);
+	return ret;
+}
+
+/**
+ * mem_cgroup_commit_charge - commit a page charge
+ * @page: page to charge
+ * @memcg: memcg to charge the page to
+ * @lrucare: page might be on LRU already
+ * @compound: charge the page as compound or small page
+ *
+ * Finalize a charge transaction started by mem_cgroup_try_charge(),
+ * after page->mapping has been set up.  This must happen atomically
+ * as part of the page instantiation, i.e. under the page table lock
+ * for anonymous pages, under the page lock for page and swap cache.
+ *
+ * In addition, the page must not be on the LRU during the commit, to
+ * prevent racing with task migration.  If it might be, use @lrucare.
+ *
+ * Use mem_cgroup_cancel_charge() to cancel the transaction instead.
+ */
+void mem_cgroup_commit_charge(struct page *page, struct mem_cgroup *memcg,
+			      bool lrucare, bool compound)
+{
+	unsigned int nr_pages = compound ? hpage_nr_pages(page) : 1;
+
+	VM_BUG_ON_PAGE(!page->mapping, page);
+	VM_BUG_ON_PAGE(PageLRU(page) && !lrucare, page);
+
+	if (mem_cgroup_disabled())
+		return;
+	/*
+	 * Swap faults will attempt to charge the same page multiple
+	 * times.  But reuse_swap_page() might have removed the page
+	 * from swapcache already, so we can't check PageSwapCache().
+	 */
+	if (!memcg)
+		return;
+
+	commit_charge(page, memcg, lrucare);
+
+	local_irq_disable();
+	mem_cgroup_charge_statistics(memcg, page, compound, nr_pages);
+	memcg_check_events(memcg, page);
+	local_irq_enable();
+
+	if (do_memsw_account() && PageSwapCache(page)) {
+		swp_entry_t entry = { .val = page_private(page) };
+		/*
+		 * The swap entry might not get freed for a long time,
+		 * let's not wait for it.  The page already received a
+		 * memory+swap charge, drop the swap entry duplicate.
+		 */
+		mem_cgroup_uncharge_swap(entry, nr_pages);
+	}
+}
+
+/**
+ * mem_cgroup_cancel_charge - cancel a page charge
+ * @page: page to charge
+ * @memcg: memcg to charge the page to
+ * @compound: charge the page as compound or small page
+ *
+ * Cancel a charge transaction started by mem_cgroup_try_charge().
+ */
+void mem_cgroup_cancel_charge(struct page *page, struct mem_cgroup *memcg,
+		bool compound)
+{
+	unsigned int nr_pages = compound ? hpage_nr_pages(page) : 1;
+
+	if (mem_cgroup_disabled())
+		return;
+	/*
+	 * Swap faults will attempt to charge the same page multiple
+	 * times.  But reuse_swap_page() might have removed the page
+	 * from swapcache already, so we can't check PageSwapCache().
+	 */
+	if (!memcg)
+		return;
+
+	cancel_charge(memcg, nr_pages);
+}
+
+struct uncharge_gather {
+	struct mem_cgroup *memcg;
+	unsigned long pgpgout;
+	unsigned long nr_anon;
+	unsigned long nr_file;
+	unsigned long nr_kmem;
+	unsigned long nr_huge;
+	unsigned long nr_shmem;
+	struct page *dummy_page;
+};
+
+static inline void uncharge_gather_clear(struct uncharge_gather *ug)
+{
+	memset(ug, 0, sizeof(*ug));
+}
+
+static void uncharge_batch(const struct uncharge_gather *ug)
+{
+	unsigned long nr_pages = ug->nr_anon + ug->nr_file + ug->nr_kmem;
+	unsigned long flags;
+
+	if (!mem_cgroup_is_root(ug->memcg)) {
+		page_counter_uncharge(&ug->memcg->memory, nr_pages);
+		if (do_memsw_account())
+			page_counter_uncharge(&ug->memcg->memsw, nr_pages);
+		if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && ug->nr_kmem)
+			page_counter_uncharge(&ug->memcg->kmem, ug->nr_kmem);
+		memcg_oom_recover(ug->memcg);
+	}
+
+	local_irq_save(flags);
+	__mod_memcg_state(ug->memcg, MEMCG_RSS, -ug->nr_anon);
+	__mod_memcg_state(ug->memcg, MEMCG_CACHE, -ug->nr_file);
+	__mod_memcg_state(ug->memcg, MEMCG_RSS_HUGE, -ug->nr_huge);
+	__mod_memcg_state(ug->memcg, NR_SHMEM, -ug->nr_shmem);
+	__count_memcg_events(ug->memcg, PGPGOUT, ug->pgpgout);
+	__this_cpu_add(ug->memcg->stat_cpu->nr_page_events, nr_pages);
+	memcg_check_events(ug->memcg, ug->dummy_page);
+	local_irq_restore(flags);
+
+	if (!mem_cgroup_is_root(ug->memcg))
+		css_put_many(&ug->memcg->css, nr_pages);
+}
+
+static void uncharge_page(struct page *page, struct uncharge_gather *ug)
+{
+	VM_BUG_ON_PAGE(PageLRU(page), page);
+	VM_BUG_ON_PAGE(page_count(page) && !is_zone_device_page(page) &&
+			!PageHWPoison(page) , page);
+
+	if (!page->mem_cgroup)
+		return;
+
+	/*
+	 * Nobody should be changing or seriously looking at
+	 * page->mem_cgroup at this point, we have fully
+	 * exclusive access to the page.
+	 */
+
+	if (ug->memcg != page->mem_cgroup) {
+		if (ug->memcg) {
+			uncharge_batch(ug);
+			uncharge_gather_clear(ug);
+		}
+		ug->memcg = page->mem_cgroup;
+	}
+
+	if (!PageKmemcg(page)) {
+		unsigned int nr_pages = 1;
+
+		if (PageTransHuge(page)) {
+			nr_pages <<= compound_order(page);
+			ug->nr_huge += nr_pages;
+		}
+		if (PageAnon(page))
+			ug->nr_anon += nr_pages;
+		else {
+			ug->nr_file += nr_pages;
+			if (PageSwapBacked(page))
+				ug->nr_shmem += nr_pages;
+		}
+		ug->pgpgout++;
+	} else {
+		ug->nr_kmem += 1 << compound_order(page);
+		__ClearPageKmemcg(page);
+	}
+
+	ug->dummy_page = page;
+	page->mem_cgroup = NULL;
+}
+
+static void uncharge_list(struct list_head *page_list)
+{
+	struct uncharge_gather ug;
+	struct list_head *next;
+
+	uncharge_gather_clear(&ug);
+
+	/*
+	 * Note that the list can be a single page->lru; hence the
+	 * do-while loop instead of a simple list_for_each_entry().
+	 */
+	next = page_list->next;
+	do {
+		struct page *page;
+
+		page = list_entry(next, struct page, lru);
+		next = page->lru.next;
+
+		uncharge_page(page, &ug);
+	} while (next != page_list);
+
+	if (ug.memcg)
+		uncharge_batch(&ug);
+}
+
+/**
+ * mem_cgroup_uncharge - uncharge a page
+ * @page: page to uncharge
+ *
+ * Uncharge a page previously charged with mem_cgroup_try_charge() and
+ * mem_cgroup_commit_charge().
+ */
+void mem_cgroup_uncharge(struct page *page)
+{
+	struct uncharge_gather ug;
+
+	if (mem_cgroup_disabled())
+		return;
+
+	/* Don't touch page->lru of any random page, pre-check: */
+	if (!page->mem_cgroup)
+		return;
+
+	uncharge_gather_clear(&ug);
+	uncharge_page(page, &ug);
+	uncharge_batch(&ug);
+}
+
+/**
+ * mem_cgroup_uncharge_list - uncharge a list of page
+ * @page_list: list of pages to uncharge
+ *
+ * Uncharge a list of pages previously charged with
+ * mem_cgroup_try_charge() and mem_cgroup_commit_charge().
+ */
+void mem_cgroup_uncharge_list(struct list_head *page_list)
+{
+	if (mem_cgroup_disabled())
+		return;
+
+	if (!list_empty(page_list))
+		uncharge_list(page_list);
+}
+
+/**
+ * mem_cgroup_migrate - charge a page's replacement
+ * @oldpage: currently circulating page
+ * @newpage: replacement page
+ *
+ * Charge @newpage as a replacement page for @oldpage. @oldpage will
+ * be uncharged upon free.
+ *
+ * Both pages must be locked, @newpage->mapping must be set up.
+ */
+void mem_cgroup_migrate(struct page *oldpage, struct page *newpage)
+{
+	struct mem_cgroup *memcg;
+	unsigned int nr_pages;
+	bool compound;
+	unsigned long flags;
+
+	VM_BUG_ON_PAGE(!PageLocked(oldpage), oldpage);
+	VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
+	VM_BUG_ON_PAGE(PageAnon(oldpage) != PageAnon(newpage), newpage);
+	VM_BUG_ON_PAGE(PageTransHuge(oldpage) != PageTransHuge(newpage),
+		       newpage);
+
+	if (mem_cgroup_disabled())
+		return;
+
+	/* Page cache replacement: new page already charged? */
+	if (newpage->mem_cgroup)
+		return;
+
+	/* Swapcache readahead pages can get replaced before being charged */
+	memcg = oldpage->mem_cgroup;
+	if (!memcg)
+		return;
+
+	/* Force-charge the new page. The old one will be freed soon */
+	compound = PageTransHuge(newpage);
+	nr_pages = compound ? hpage_nr_pages(newpage) : 1;
+
+	page_counter_charge(&memcg->memory, nr_pages);
+	if (do_memsw_account())
+		page_counter_charge(&memcg->memsw, nr_pages);
+	css_get_many(&memcg->css, nr_pages);
+
+	commit_charge(newpage, memcg, false);
+
+	local_irq_save(flags);
+	mem_cgroup_charge_statistics(memcg, newpage, compound, nr_pages);
+	memcg_check_events(memcg, newpage);
+	local_irq_restore(flags);
+}
+
+DEFINE_STATIC_KEY_FALSE(memcg_sockets_enabled_key);
+EXPORT_SYMBOL(memcg_sockets_enabled_key);
+
+void mem_cgroup_sk_alloc(struct sock *sk)
+{
+	struct mem_cgroup *memcg;
+
+	if (!mem_cgroup_sockets_enabled)
+		return;
+
+	/* Do not associate the sock with unrelated interrupted task's memcg. */
+	if (in_interrupt())
+		return;
+
+	rcu_read_lock();
+	memcg = mem_cgroup_from_task(current);
+	if (memcg == root_mem_cgroup)
+		goto out;
+	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && !memcg->tcpmem_active)
+		goto out;
+	if (css_tryget_online(&memcg->css))
+		sk->sk_memcg = memcg;
+out:
+	rcu_read_unlock();
+}
+
+void mem_cgroup_sk_free(struct sock *sk)
+{
+	if (sk->sk_memcg)
+		css_put(&sk->sk_memcg->css);
+}
+
+/**
+ * mem_cgroup_charge_skmem - charge socket memory
+ * @memcg: memcg to charge
+ * @nr_pages: number of pages to charge
+ *
+ * Charges @nr_pages to @memcg. Returns %true if the charge fit within
+ * @memcg's configured limit, %false if the charge had to be forced.
+ */
+bool mem_cgroup_charge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages)
+{
+	gfp_t gfp_mask = GFP_KERNEL;
+
+	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
+		struct page_counter *fail;
+
+		if (page_counter_try_charge(&memcg->tcpmem, nr_pages, &fail)) {
+			memcg->tcpmem_pressure = 0;
+			return true;
+		}
+		page_counter_charge(&memcg->tcpmem, nr_pages);
+		memcg->tcpmem_pressure = 1;
+		return false;
+	}
+
+	/* Don't block in the packet receive path */
+	if (in_softirq())
+		gfp_mask = GFP_NOWAIT;
+
+	mod_memcg_state(memcg, MEMCG_SOCK, nr_pages);
+
+	if (try_charge(memcg, gfp_mask, nr_pages) == 0)
+		return true;
+
+	try_charge(memcg, gfp_mask|__GFP_NOFAIL, nr_pages);
+	return false;
+}
+
+/**
+ * mem_cgroup_uncharge_skmem - uncharge socket memory
+ * @memcg: memcg to uncharge
+ * @nr_pages: number of pages to uncharge
+ */
+void mem_cgroup_uncharge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages)
+{
+	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
+		page_counter_uncharge(&memcg->tcpmem, nr_pages);
+		return;
+	}
+
+	mod_memcg_state(memcg, MEMCG_SOCK, -nr_pages);
+
+	refill_stock(memcg, nr_pages);
+}
+
+static int __init cgroup_memory(char *s)
+{
+	char *token;
+
+	while ((token = strsep(&s, ",")) != NULL) {
+		if (!*token)
+			continue;
+		if (!strcmp(token, "nosocket"))
+			cgroup_memory_nosocket = true;
+		if (!strcmp(token, "nokmem"))
+			cgroup_memory_nokmem = true;
+	}
+	return 1;
+}
+__setup("cgroup.memory=", cgroup_memory);
+
+/*
+ * subsys_initcall() for memory controller.
+ *
+ * Some parts like memcg_hotplug_cpu_dead() have to be initialized from this
+ * context because of lock dependencies (cgroup_lock -> cpu hotplug) but
+ * basically everything that doesn't depend on a specific mem_cgroup structure
+ * should be initialized from here.
+ */
+static int __init mem_cgroup_init(void)
+{
+	int cpu, node;
+
+#ifdef CONFIG_MEMCG_KMEM
+	/*
+	 * Kmem cache creation is mostly done with the slab_mutex held,
+	 * so use a workqueue with limited concurrency to avoid stalling
+	 * all worker threads in case lots of cgroups are created and
+	 * destroyed simultaneously.
+	 */
+	memcg_kmem_cache_wq = alloc_workqueue("memcg_kmem_cache", 0, 1);
+	BUG_ON(!memcg_kmem_cache_wq);
+#endif
+
+	cpuhp_setup_state_nocalls(CPUHP_MM_MEMCQ_DEAD, "mm/memctrl:dead", NULL,
+				  memcg_hotplug_cpu_dead);
+
+	for_each_possible_cpu(cpu)
+		INIT_WORK(&per_cpu_ptr(&memcg_stock, cpu)->work,
+			  drain_local_stock);
+
+	for_each_node(node) {
+		struct mem_cgroup_tree_per_node *rtpn;
+
+		rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL,
+				    node_online(node) ? node : NUMA_NO_NODE);
+
+		rtpn->rb_root = RB_ROOT;
+		rtpn->rb_rightmost = NULL;
+		spin_lock_init(&rtpn->lock);
+		soft_limit_tree.rb_tree_per_node[node] = rtpn;
+	}
+
+	return 0;
+}
+subsys_initcall(mem_cgroup_init);
+
+#ifdef CONFIG_MEMCG_SWAP
+static struct mem_cgroup *mem_cgroup_id_get_online(struct mem_cgroup *memcg)
+{
+	while (!atomic_inc_not_zero(&memcg->id.ref)) {
+		/*
+		 * The root cgroup cannot be destroyed, so it's refcount must
+		 * always be >= 1.
+		 */
+		if (WARN_ON_ONCE(memcg == root_mem_cgroup)) {
+			VM_BUG_ON(1);
+			break;
+		}
+		memcg = parent_mem_cgroup(memcg);
+		if (!memcg)
+			memcg = root_mem_cgroup;
+	}
+	return memcg;
+}
+
+/**
+ * mem_cgroup_swapout - transfer a memsw charge to swap
+ * @page: page whose memsw charge to transfer
+ * @entry: swap entry to move the charge to
+ *
+ * Transfer the memsw charge of @page to @entry.
+ */
+void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
+{
+	struct mem_cgroup *memcg, *swap_memcg;
+	unsigned int nr_entries;
+	unsigned short oldid;
+
+	VM_BUG_ON_PAGE(PageLRU(page), page);
+	VM_BUG_ON_PAGE(page_count(page), page);
+
+	if (!do_memsw_account())
+		return;
+
+	memcg = page->mem_cgroup;
+
+	/* Readahead page, never charged */
+	if (!memcg)
+		return;
+
+	/*
+	 * In case the memcg owning these pages has been offlined and doesn't
+	 * have an ID allocated to it anymore, charge the closest online
+	 * ancestor for the swap instead and transfer the memory+swap charge.
+	 */
+	swap_memcg = mem_cgroup_id_get_online(memcg);
+	nr_entries = hpage_nr_pages(page);
+	/* Get references for the tail pages, too */
+	if (nr_entries > 1)
+		mem_cgroup_id_get_many(swap_memcg, nr_entries - 1);
+	oldid = swap_cgroup_record(entry, mem_cgroup_id(swap_memcg),
+				   nr_entries);
+	VM_BUG_ON_PAGE(oldid, page);
+	mod_memcg_state(swap_memcg, MEMCG_SWAP, nr_entries);
+
+	page->mem_cgroup = NULL;
+
+	if (!mem_cgroup_is_root(memcg))
+		page_counter_uncharge(&memcg->memory, nr_entries);
+
+	if (memcg != swap_memcg) {
+		if (!mem_cgroup_is_root(swap_memcg))
+			page_counter_charge(&swap_memcg->memsw, nr_entries);
+		page_counter_uncharge(&memcg->memsw, nr_entries);
+	}
+
+	/*
+	 * Interrupts should be disabled here because the caller holds the
+	 * i_pages lock which is taken with interrupts-off. It is
+	 * important here to have the interrupts disabled because it is the
+	 * only synchronisation we have for updating the per-CPU variables.
+	 */
+	VM_BUG_ON(!irqs_disabled());
+	mem_cgroup_charge_statistics(memcg, page, PageTransHuge(page),
+				     -nr_entries);
+	memcg_check_events(memcg, page);
+
+	if (!mem_cgroup_is_root(memcg))
+		css_put_many(&memcg->css, nr_entries);
+}
+
+/**
+ * mem_cgroup_try_charge_swap - try charging swap space for a page
+ * @page: page being added to swap
+ * @entry: swap entry to charge
+ *
+ * Try to charge @page's memcg for the swap space at @entry.
+ *
+ * Returns 0 on success, -ENOMEM on failure.
+ */
+int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry)
+{
+	unsigned int nr_pages = hpage_nr_pages(page);
+	struct page_counter *counter;
+	struct mem_cgroup *memcg;
+	unsigned short oldid;
+
+	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) || !do_swap_account)
+		return 0;
+
+	memcg = page->mem_cgroup;
+
+	/* Readahead page, never charged */
+	if (!memcg)
+		return 0;
+
+	if (!entry.val) {
+		memcg_memory_event(memcg, MEMCG_SWAP_FAIL);
+		return 0;
+	}
+
+	memcg = mem_cgroup_id_get_online(memcg);
+
+	if (!mem_cgroup_is_root(memcg) &&
+	    !page_counter_try_charge(&memcg->swap, nr_pages, &counter)) {
+		memcg_memory_event(memcg, MEMCG_SWAP_MAX);
+		memcg_memory_event(memcg, MEMCG_SWAP_FAIL);
+		mem_cgroup_id_put(memcg);
+		return -ENOMEM;
+	}
+
+	/* Get references for the tail pages, too */
+	if (nr_pages > 1)
+		mem_cgroup_id_get_many(memcg, nr_pages - 1);
+	oldid = swap_cgroup_record(entry, mem_cgroup_id(memcg), nr_pages);
+	VM_BUG_ON_PAGE(oldid, page);
+	mod_memcg_state(memcg, MEMCG_SWAP, nr_pages);
+
+	return 0;
+}
+
+/**
+ * mem_cgroup_uncharge_swap - uncharge swap space
+ * @entry: swap entry to uncharge
+ * @nr_pages: the amount of swap space to uncharge
+ */
+void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages)
+{
+	struct mem_cgroup *memcg;
+	unsigned short id;
+
+	if (!do_swap_account)
+		return;
+
+	id = swap_cgroup_record(entry, 0, nr_pages);
+	rcu_read_lock();
+	memcg = mem_cgroup_from_id(id);
+	if (memcg) {
+		if (!mem_cgroup_is_root(memcg)) {
+			if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
+				page_counter_uncharge(&memcg->swap, nr_pages);
+			else
+				page_counter_uncharge(&memcg->memsw, nr_pages);
+		}
+		mod_memcg_state(memcg, MEMCG_SWAP, -nr_pages);
+		mem_cgroup_id_put_many(memcg, nr_pages);
+	}
+	rcu_read_unlock();
+}
+
+long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
+{
+	long nr_swap_pages = get_nr_swap_pages();
+
+	if (!do_swap_account || !cgroup_subsys_on_dfl(memory_cgrp_subsys))
+		return nr_swap_pages;
+	for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg))
+		nr_swap_pages = min_t(long, nr_swap_pages,
+				      READ_ONCE(memcg->swap.max) -
+				      page_counter_read(&memcg->swap));
+	return nr_swap_pages;
+}
+
+bool mem_cgroup_swap_full(struct page *page)
+{
+	struct mem_cgroup *memcg;
+
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
+
+	if (vm_swap_full())
+		return true;
+	if (!do_swap_account || !cgroup_subsys_on_dfl(memory_cgrp_subsys))
+		return false;
+
+	memcg = page->mem_cgroup;
+	if (!memcg)
+		return false;
+
+	for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg))
+		if (page_counter_read(&memcg->swap) * 2 >= memcg->swap.max)
+			return true;
+
+	return false;
+}
+
+/* for remember boot option*/
+#ifdef CONFIG_MEMCG_SWAP_ENABLED
+static int really_do_swap_account __initdata = 1;
+#else
+static int really_do_swap_account __initdata;
+#endif
+
+static int __init enable_swap_account(char *s)
+{
+	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);
+
+static u64 swap_current_read(struct cgroup_subsys_state *css,
+			     struct cftype *cft)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
+
+	return (u64)page_counter_read(&memcg->swap) * PAGE_SIZE;
+}
+
+static int swap_max_show(struct seq_file *m, void *v)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+	unsigned long max = READ_ONCE(memcg->swap.max);
+
+	if (max == PAGE_COUNTER_MAX)
+		seq_puts(m, "max\n");
+	else
+		seq_printf(m, "%llu\n", (u64)max * PAGE_SIZE);
+
+	return 0;
+}
+
+static ssize_t swap_max_write(struct kernfs_open_file *of,
+			      char *buf, size_t nbytes, loff_t off)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+	unsigned long max;
+	int err;
+
+	buf = strstrip(buf);
+	err = page_counter_memparse(buf, "max", &max);
+	if (err)
+		return err;
+
+	xchg(&memcg->swap.max, max);
+
+	return nbytes;
+}
+
+static int swap_events_show(struct seq_file *m, void *v)
+{
+	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+
+	seq_printf(m, "max %lu\n",
+		   atomic_long_read(&memcg->memory_events[MEMCG_SWAP_MAX]));
+	seq_printf(m, "fail %lu\n",
+		   atomic_long_read(&memcg->memory_events[MEMCG_SWAP_FAIL]));
+
+	return 0;
+}
+
+static struct cftype swap_files[] = {
+	{
+		.name = "swap.current",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.read_u64 = swap_current_read,
+	},
+	{
+		.name = "swap.max",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.seq_show = swap_max_show,
+		.write = swap_max_write,
+	},
+	{
+		.name = "swap.events",
+		.flags = CFTYPE_NOT_ON_ROOT,
+		.file_offset = offsetof(struct mem_cgroup, swap_events_file),
+		.seq_show = swap_events_show,
+	},
+	{ }	/* terminate */
+};
+
+static struct cftype memsw_cgroup_files[] = {
+	{
+		.name = "memsw.usage_in_bytes",
+		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE),
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "memsw.max_usage_in_bytes",
+		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE),
+		.write = mem_cgroup_reset,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "memsw.limit_in_bytes",
+		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT),
+		.write = mem_cgroup_write,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "memsw.failcnt",
+		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT),
+		.write = mem_cgroup_reset,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{ },	/* terminate */
+};
+
+static int __init mem_cgroup_swap_init(void)
+{
+	if (!mem_cgroup_disabled() && really_do_swap_account) {
+		do_swap_account = 1;
+		WARN_ON(cgroup_add_dfl_cftypes(&memory_cgrp_subsys,
+					       swap_files));
+		WARN_ON(cgroup_add_legacy_cftypes(&memory_cgrp_subsys,
+						  memsw_cgroup_files));
+	}
+	return 0;
+}
+subsys_initcall(mem_cgroup_swap_init);
+
+#endif /* CONFIG_MEMCG_SWAP */