#include <linux/mm.h>
  #include <linux/mmzone.h>
  #include <linux/bootmem.h>
  #include <linux/bit_spinlock.h>
  #include <linux/page_cgroup.h>
  #include <linux/hash.h>

  #include <linux/slab.h>

  #include <linux/memory.h>

  #include <linux/vmalloc.h>

  #include <linux/cgroup.h>

  #include <linux/swapops.h>

  #include <linux/kmemleak.h>

  static unsigned long total_usage;
  
  #if !defined(CONFIG_SPARSEMEM)

  void __meminit pgdat_page_cgroup_init(struct pglist_data *pgdat)

  {
  	pgdat->node_page_cgroup = NULL;
  }
  
  struct page_cgroup *lookup_page_cgroup(struct page *page)
  {
  	unsigned long pfn = page_to_pfn(page);
  	unsigned long offset;
  	struct page_cgroup *base;
  
  	base = NODE_DATA(page_to_nid(page))->node_page_cgroup;

  #ifdef CONFIG_DEBUG_VM
  	/*
  	 * The sanity checks the page allocator does upon freeing a
  	 * page can reach here before the page_cgroup arrays are
  	 * allocated when feeding a range of pages to the allocator
  	 * for the first time during bootup or memory hotplug.
  	 */

  	if (unlikely(!base))
  		return NULL;

  #endif

  	offset = pfn - NODE_DATA(page_to_nid(page))->node_start_pfn;
  	return base + offset;
  }
  
  static int __init alloc_node_page_cgroup(int nid)
  {

  	struct page_cgroup *base;

  	unsigned long table_size;

  	unsigned long nr_pages;

  	nr_pages = NODE_DATA(nid)->node_spanned_pages;

  	if (!nr_pages)
  		return 0;

  	table_size = sizeof(struct page_cgroup) * nr_pages;

  	base = memblock_virt_alloc_try_nid_nopanic(
  			table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
  			BOOTMEM_ALLOC_ACCESSIBLE, nid);

  	if (!base)

  		return -ENOMEM;

  	NODE_DATA(nid)->node_page_cgroup = base;
  	total_usage += table_size;
  	return 0;
  }

  void __init page_cgroup_init_flatmem(void)

  {
  
  	int nid, fail;

  	if (mem_cgroup_disabled())

  		return;

  	for_each_online_node(nid)  {
  		fail = alloc_node_page_cgroup(nid);
  		if (fail)
  			goto fail;
  	}
  	printk(KERN_INFO "allocated %ld bytes of page_cgroup
  ", total_usage);

  	printk(KERN_INFO "please try 'cgroup_disable=memory' option if you"
  	" don't want memory cgroups
  ");

  	return;
  fail:

  	printk(KERN_CRIT "allocation of page_cgroup failed.
  ");
  	printk(KERN_CRIT "please try 'cgroup_disable=memory' boot option
  ");

  	panic("Out of memory");
  }
  
  #else /* CONFIG_FLAT_NODE_MEM_MAP */
  
  struct page_cgroup *lookup_page_cgroup(struct page *page)
  {
  	unsigned long pfn = page_to_pfn(page);
  	struct mem_section *section = __pfn_to_section(pfn);

  #ifdef CONFIG_DEBUG_VM
  	/*
  	 * The sanity checks the page allocator does upon freeing a
  	 * page can reach here before the page_cgroup arrays are
  	 * allocated when feeding a range of pages to the allocator
  	 * for the first time during bootup or memory hotplug.
  	 */

  	if (!section->page_cgroup)
  		return NULL;

  #endif

  	return section->page_cgroup + pfn;
  }

  static void *__meminit alloc_page_cgroup(size_t size, int nid)

  {

  	gfp_t flags = GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN;

  	void *addr = NULL;

  	addr = alloc_pages_exact_nid(nid, size, flags);
  	if (addr) {
  		kmemleak_alloc(addr, size, 1, flags);

  		return addr;

  	}

  
  	if (node_state(nid, N_HIGH_MEMORY))

  		addr = vzalloc_node(size, nid);

  	else

  		addr = vzalloc(size);

  
  	return addr;
  }

  static int __meminit init_section_page_cgroup(unsigned long pfn, int nid)

  {

  	struct mem_section *section;

  	struct page_cgroup *base;

  	unsigned long table_size;

  	section = __pfn_to_section(pfn);

  
  	if (section->page_cgroup)
  		return 0;

  	table_size = sizeof(struct page_cgroup) * PAGES_PER_SECTION;

  	base = alloc_page_cgroup(table_size, nid);

  	/*
  	 * The value stored in section->page_cgroup is (base - pfn)
  	 * and it does not point to the memory block allocated above,
  	 * causing kmemleak false positives.
  	 */
  	kmemleak_not_leak(base);

  
  	if (!base) {
  		printk(KERN_ERR "page cgroup allocation failure
  ");
  		return -ENOMEM;
  	}

  	/*
  	 * The passed "pfn" may not be aligned to SECTION.  For the calculation
  	 * we need to apply a mask.
  	 */
  	pfn &= PAGE_SECTION_MASK;

  	section->page_cgroup = base - pfn;
  	total_usage += table_size;
  	return 0;
  }
  #ifdef CONFIG_MEMORY_HOTPLUG

  static void free_page_cgroup(void *addr)
  {
  	if (is_vmalloc_addr(addr)) {
  		vfree(addr);
  	} else {
  		struct page *page = virt_to_page(addr);
  		size_t table_size =
  			sizeof(struct page_cgroup) * PAGES_PER_SECTION;
  
  		BUG_ON(PageReserved(page));
  		free_pages_exact(addr, table_size);
  	}
  }

  static void __free_page_cgroup(unsigned long pfn)

  {
  	struct mem_section *ms;
  	struct page_cgroup *base;
  
  	ms = __pfn_to_section(pfn);
  	if (!ms || !ms->page_cgroup)
  		return;
  	base = ms->page_cgroup + pfn;

  	free_page_cgroup(base);
  	ms->page_cgroup = NULL;

  }

  static int __meminit online_page_cgroup(unsigned long start_pfn,
  				unsigned long nr_pages,
  				int nid)

  {
  	unsigned long start, end, pfn;
  	int fail = 0;

  	start = SECTION_ALIGN_DOWN(start_pfn);
  	end = SECTION_ALIGN_UP(start_pfn + nr_pages);

  	if (nid == -1) {
  		/*
  		 * In this case, "nid" already exists and contains valid memory.
  		 * "start_pfn" passed to us is a pfn which is an arg for
  		 * online__pages(), and start_pfn should exist.
  		 */
  		nid = pfn_to_nid(start_pfn);
  		VM_BUG_ON(!node_state(nid, N_ONLINE));
  	}

  	for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) {
  		if (!pfn_present(pfn))
  			continue;

  		fail = init_section_page_cgroup(pfn, nid);

  	}
  	if (!fail)
  		return 0;
  
  	/* rollback */
  	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
  		__free_page_cgroup(pfn);
  
  	return -ENOMEM;
  }

  static int __meminit offline_page_cgroup(unsigned long start_pfn,
  				unsigned long nr_pages, int nid)

  {
  	unsigned long start, end, pfn;

  	start = SECTION_ALIGN_DOWN(start_pfn);
  	end = SECTION_ALIGN_UP(start_pfn + nr_pages);

  
  	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
  		__free_page_cgroup(pfn);
  	return 0;
  
  }

  static int __meminit page_cgroup_callback(struct notifier_block *self,

  			       unsigned long action, void *arg)
  {
  	struct memory_notify *mn = arg;
  	int ret = 0;
  	switch (action) {
  	case MEM_GOING_ONLINE:
  		ret = online_page_cgroup(mn->start_pfn,
  				   mn->nr_pages, mn->status_change_nid);
  		break;

  	case MEM_OFFLINE:
  		offline_page_cgroup(mn->start_pfn,
  				mn->nr_pages, mn->status_change_nid);
  		break;

  	case MEM_CANCEL_ONLINE:

  		offline_page_cgroup(mn->start_pfn,
  				mn->nr_pages, mn->status_change_nid);
  		break;

  	case MEM_GOING_OFFLINE:
  		break;
  	case MEM_ONLINE:
  	case MEM_CANCEL_OFFLINE:
  		break;
  	}

  	return notifier_from_errno(ret);

  }
  
  #endif
  
  void __init page_cgroup_init(void)
  {
  	unsigned long pfn;

  	int nid;

  	if (mem_cgroup_disabled())

  		return;

  	for_each_node_state(nid, N_MEMORY) {

  		unsigned long start_pfn, end_pfn;
  
  		start_pfn = node_start_pfn(nid);
  		end_pfn = node_end_pfn(nid);
  		/*
  		 * start_pfn and end_pfn may not be aligned to SECTION and the
  		 * page->flags of out of node pages are not initialized.  So we
  		 * scan [start_pfn, the biggest section's pfn < end_pfn) here.
  		 */
  		for (pfn = start_pfn;
  		     pfn < end_pfn;
                       pfn = ALIGN(pfn + 1, PAGES_PER_SECTION)) {
  
  			if (!pfn_valid(pfn))
  				continue;
  			/*
  			 * Nodes's pfns can be overlapping.
  			 * We know some arch can have a nodes layout such as
  			 * -------------pfn-------------->
  			 * N0 | N1 | N2 | N0 | N1 | N2|....
  			 */
  			if (pfn_to_nid(pfn) != nid)
  				continue;
  			if (init_section_page_cgroup(pfn, nid))
  				goto oom;
  		}

  	}

  	hotplug_memory_notifier(page_cgroup_callback, 0);

  	printk(KERN_INFO "allocated %ld bytes of page_cgroup
  ", total_usage);

  	printk(KERN_INFO "please try 'cgroup_disable=memory' option if you "
  			 "don't want memory cgroups
  ");
  	return;
  oom:
  	printk(KERN_CRIT "try 'cgroup_disable=memory' boot option
  ");
  	panic("Out of memory");

  }

  void __meminit pgdat_page_cgroup_init(struct pglist_data *pgdat)

  {
  	return;
  }
  
  #endif

  #ifdef CONFIG_MEMCG_SWAP

  
  static DEFINE_MUTEX(swap_cgroup_mutex);
  struct swap_cgroup_ctrl {
  	struct page **map;
  	unsigned long length;

  	spinlock_t	lock;

  };

  static struct swap_cgroup_ctrl swap_cgroup_ctrl[MAX_SWAPFILES];

  struct swap_cgroup {

  	unsigned short		id;

  };
  #define SC_PER_PAGE	(PAGE_SIZE/sizeof(struct swap_cgroup))

  
  /*
   * SwapCgroup implements "lookup" and "exchange" operations.
   * In typical usage, this swap_cgroup is accessed via memcg's charge/uncharge
   * against SwapCache. At swap_free(), this is accessed directly from swap.
   *
   * This means,
   *  - we have no race in "exchange" when we're accessed via SwapCache because
   *    SwapCache(and its swp_entry) is under lock.
   *  - When called via swap_free(), there is no user of this entry and no race.
   * Then, we don't need lock around "exchange".
   *
   * TODO: we can push these buffers out to HIGHMEM.
   */
  
  /*
   * allocate buffer for swap_cgroup.
   */
  static int swap_cgroup_prepare(int type)
  {
  	struct page *page;
  	struct swap_cgroup_ctrl *ctrl;
  	unsigned long idx, max;

  	ctrl = &swap_cgroup_ctrl[type];
  
  	for (idx = 0; idx < ctrl->length; idx++) {
  		page = alloc_page(GFP_KERNEL | __GFP_ZERO);
  		if (!page)
  			goto not_enough_page;
  		ctrl->map[idx] = page;
  	}
  	return 0;
  not_enough_page:
  	max = idx;
  	for (idx = 0; idx < max; idx++)
  		__free_page(ctrl->map[idx]);
  
  	return -ENOMEM;
  }

  static struct swap_cgroup *lookup_swap_cgroup(swp_entry_t ent,
  					struct swap_cgroup_ctrl **ctrlp)
  {
  	pgoff_t offset = swp_offset(ent);
  	struct swap_cgroup_ctrl *ctrl;
  	struct page *mappage;

  	struct swap_cgroup *sc;

  
  	ctrl = &swap_cgroup_ctrl[swp_type(ent)];
  	if (ctrlp)
  		*ctrlp = ctrl;
  
  	mappage = ctrl->map[offset / SC_PER_PAGE];

  	sc = page_address(mappage);
  	return sc + offset % SC_PER_PAGE;

  }

  /**

   * swap_cgroup_cmpxchg - cmpxchg mem_cgroup's id for this swp_entry.

   * @ent: swap entry to be cmpxchged

   * @old: old id
   * @new: new id
   *
   * Returns old id at success, 0 at failure.

   * (There is no mem_cgroup using 0 as its id)

   */
  unsigned short swap_cgroup_cmpxchg(swp_entry_t ent,
  					unsigned short old, unsigned short new)
  {

  	struct swap_cgroup_ctrl *ctrl;

  	struct swap_cgroup *sc;

  	unsigned long flags;
  	unsigned short retval;

  	sc = lookup_swap_cgroup(ent, &ctrl);

  	spin_lock_irqsave(&ctrl->lock, flags);
  	retval = sc->id;
  	if (retval == old)
  		sc->id = new;

  	else

  		retval = 0;
  	spin_unlock_irqrestore(&ctrl->lock, flags);
  	return retval;

  }
  
  /**

   * swap_cgroup_record - record mem_cgroup for this swp_entry.
   * @ent: swap entry to be recorded into

   * @id: mem_cgroup to be recorded

   *

   * Returns old value at success, 0 at failure.
   * (Of course, old value can be 0.)

   */

  unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id)

  {

  	struct swap_cgroup_ctrl *ctrl;

  	struct swap_cgroup *sc;

  	unsigned short old;

  	unsigned long flags;

  	sc = lookup_swap_cgroup(ent, &ctrl);

  	spin_lock_irqsave(&ctrl->lock, flags);
  	old = sc->id;
  	sc->id = id;
  	spin_unlock_irqrestore(&ctrl->lock, flags);

  
  	return old;
  }
  
  /**

   * lookup_swap_cgroup_id - lookup mem_cgroup id tied to swap entry

   * @ent: swap entry to be looked up.
   *

   * Returns ID of mem_cgroup at success. 0 at failure. (0 is invalid ID)

   */

  unsigned short lookup_swap_cgroup_id(swp_entry_t ent)

  {

  	return lookup_swap_cgroup(ent, NULL)->id;

  }
  
  int swap_cgroup_swapon(int type, unsigned long max_pages)
  {
  	void *array;
  	unsigned long array_size;
  	unsigned long length;
  	struct swap_cgroup_ctrl *ctrl;
  
  	if (!do_swap_account)
  		return 0;

  	length = DIV_ROUND_UP(max_pages, SC_PER_PAGE);

  	array_size = length * sizeof(void *);

  	array = vzalloc(array_size);

  	if (!array)
  		goto nomem;

  	ctrl = &swap_cgroup_ctrl[type];
  	mutex_lock(&swap_cgroup_mutex);
  	ctrl->length = length;
  	ctrl->map = array;

  	spin_lock_init(&ctrl->lock);

  	if (swap_cgroup_prepare(type)) {
  		/* memory shortage */
  		ctrl->map = NULL;
  		ctrl->length = 0;

  		mutex_unlock(&swap_cgroup_mutex);

  		vfree(array);

  		goto nomem;
  	}
  	mutex_unlock(&swap_cgroup_mutex);

  	return 0;
  nomem:
  	printk(KERN_INFO "couldn't allocate enough memory for swap_cgroup.
  ");
  	printk(KERN_INFO

  		"swap_cgroup can be disabled by swapaccount=0 boot option
  ");

  	return -ENOMEM;
  }
  
  void swap_cgroup_swapoff(int type)
  {

  	struct page **map;
  	unsigned long i, length;

  	struct swap_cgroup_ctrl *ctrl;
  
  	if (!do_swap_account)
  		return;
  
  	mutex_lock(&swap_cgroup_mutex);
  	ctrl = &swap_cgroup_ctrl[type];

  	map = ctrl->map;
  	length = ctrl->length;
  	ctrl->map = NULL;
  	ctrl->length = 0;
  	mutex_unlock(&swap_cgroup_mutex);
  
  	if (map) {
  		for (i = 0; i < length; i++) {
  			struct page *page = map[i];

  			if (page)
  				__free_page(page);
  		}

  		vfree(map);

  	}

  }
  
  #endif