#ifndef _LINUX_HUGE_MM_H
  #define _LINUX_HUGE_MM_H
  
  extern int do_huge_pmd_anonymous_page(struct mm_struct *mm,
  				      struct vm_area_struct *vma,
  				      unsigned long address, pmd_t *pmd,
  				      unsigned int flags);
  extern int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
  			 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
  			 struct vm_area_struct *vma);

  extern void huge_pmd_set_accessed(struct mm_struct *mm,
  				  struct vm_area_struct *vma,
  				  unsigned long address, pmd_t *pmd,
  				  pmd_t orig_pmd, int dirty);

  extern int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
  			       unsigned long address, pmd_t *pmd,
  			       pmd_t orig_pmd);

  extern struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,

  					  unsigned long addr,
  					  pmd_t *pmd,
  					  unsigned int flags);
  extern int zap_huge_pmd(struct mmu_gather *tlb,
  			struct vm_area_struct *vma,

  			pmd_t *pmd, unsigned long addr);

  extern int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
  			unsigned long addr, unsigned long end,
  			unsigned char *vec);

  extern int move_huge_pmd(struct vm_area_struct *vma,
  			 struct vm_area_struct *new_vma,
  			 unsigned long old_addr,
  			 unsigned long new_addr, unsigned long old_end,
  			 pmd_t *old_pmd, pmd_t *new_pmd);

  extern int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,

  			unsigned long addr, pgprot_t newprot,
  			int prot_numa);

  
  enum transparent_hugepage_flag {
  	TRANSPARENT_HUGEPAGE_FLAG,
  	TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
  	TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
  	TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG,

  	TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG,

  	TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG,

  #ifdef CONFIG_DEBUG_VM
  	TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG,
  #endif
  };
  
  enum page_check_address_pmd_flag {
  	PAGE_CHECK_ADDRESS_PMD_FLAG,
  	PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG,
  	PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG,
  };
  extern pmd_t *page_check_address_pmd(struct page *page,
  				     struct mm_struct *mm,
  				     unsigned long address,

  				     enum page_check_address_pmd_flag flag,
  				     spinlock_t **ptl);

  #define HPAGE_PMD_ORDER (HPAGE_PMD_SHIFT-PAGE_SHIFT)
  #define HPAGE_PMD_NR (1<<HPAGE_PMD_ORDER)

  #ifdef CONFIG_TRANSPARENT_HUGEPAGE

  #define HPAGE_PMD_SHIFT PMD_SHIFT
  #define HPAGE_PMD_SIZE	((1UL) << HPAGE_PMD_SHIFT)
  #define HPAGE_PMD_MASK	(~(HPAGE_PMD_SIZE - 1))

  extern bool is_vma_temporary_stack(struct vm_area_struct *vma);

  #define transparent_hugepage_enabled(__vma)				\

  	((transparent_hugepage_flags &					\
  	  (1<<TRANSPARENT_HUGEPAGE_FLAG) ||				\
  	  (transparent_hugepage_flags &					\
  	   (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG) &&			\
  	   ((__vma)->vm_flags & VM_HUGEPAGE))) &&			\

  	 !((__vma)->vm_flags & VM_NOHUGEPAGE) &&			\
  	 !is_vma_temporary_stack(__vma))

  #define transparent_hugepage_defrag(__vma)				\
  	((transparent_hugepage_flags &					\
  	  (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)) ||			\
  	 (transparent_hugepage_flags &					\
  	  (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG) &&		\
  	  (__vma)->vm_flags & VM_HUGEPAGE))

  #define transparent_hugepage_use_zero_page()				\
  	(transparent_hugepage_flags &					\
  	 (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG))

  #ifdef CONFIG_DEBUG_VM
  #define transparent_hugepage_debug_cow()				\
  	(transparent_hugepage_flags &					\
  	 (1<<TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG))
  #else /* CONFIG_DEBUG_VM */
  #define transparent_hugepage_debug_cow() 0
  #endif /* CONFIG_DEBUG_VM */
  
  extern unsigned long transparent_hugepage_flags;
  extern int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
  			  pmd_t *dst_pmd, pmd_t *src_pmd,
  			  struct vm_area_struct *vma,
  			  unsigned long addr, unsigned long end);

  extern int split_huge_page_to_list(struct page *page, struct list_head *list);
  static inline int split_huge_page(struct page *page)
  {
  	return split_huge_page_to_list(page, NULL);
  }

  extern void __split_huge_page_pmd(struct vm_area_struct *vma,
  		unsigned long address, pmd_t *pmd);
  #define split_huge_page_pmd(__vma, __address, __pmd)			\

  	do {								\
  		pmd_t *____pmd = (__pmd);				\
  		if (unlikely(pmd_trans_huge(*____pmd)))			\

  			__split_huge_page_pmd(__vma, __address,		\
  					____pmd);			\

  	}  while (0)
  #define wait_split_huge_page(__anon_vma, __pmd)				\
  	do {								\
  		pmd_t *____pmd = (__pmd);				\

  		anon_vma_lock_write(__anon_vma);			\

  		anon_vma_unlock_write(__anon_vma);			\

  		BUG_ON(pmd_trans_splitting(*____pmd) ||			\
  		       pmd_trans_huge(*____pmd));			\
  	} while (0)

  extern void split_huge_page_pmd_mm(struct mm_struct *mm, unsigned long address,
  		pmd_t *pmd);

  #if HPAGE_PMD_ORDER >= MAX_ORDER

  #error "hugepages can't be allocated by the buddy allocator"
  #endif

  extern int hugepage_madvise(struct vm_area_struct *vma,
  			    unsigned long *vm_flags, int advice);

  extern void __vma_adjust_trans_huge(struct vm_area_struct *vma,
  				    unsigned long start,
  				    unsigned long end,
  				    long adjust_next);

  extern int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
  		spinlock_t **ptl);

  /* mmap_sem must be held on entry */

  static inline int pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
  		spinlock_t **ptl)

  {
  	VM_BUG_ON(!rwsem_is_locked(&vma->vm_mm->mmap_sem));
  	if (pmd_trans_huge(*pmd))

  		return __pmd_trans_huge_lock(pmd, vma, ptl);

  	else
  		return 0;
  }

  static inline void vma_adjust_trans_huge(struct vm_area_struct *vma,
  					 unsigned long start,
  					 unsigned long end,
  					 long adjust_next)
  {

  	if (!vma->anon_vma || vma->vm_ops)

  		return;
  	__vma_adjust_trans_huge(vma, start, end, adjust_next);
  }

  static inline int hpage_nr_pages(struct page *page)
  {
  	if (unlikely(PageTransHuge(page)))
  		return HPAGE_PMD_NR;
  	return 1;
  }

  extern int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
  				unsigned long addr, pmd_t pmd, pmd_t *pmdp);

  #else /* CONFIG_TRANSPARENT_HUGEPAGE */

  #define HPAGE_PMD_SHIFT ({ BUILD_BUG(); 0; })
  #define HPAGE_PMD_MASK ({ BUILD_BUG(); 0; })
  #define HPAGE_PMD_SIZE ({ BUILD_BUG(); 0; })

  #define hpage_nr_pages(x) 1

  #define transparent_hugepage_enabled(__vma) 0
  
  #define transparent_hugepage_flags 0UL

  static inline int
  split_huge_page_to_list(struct page *page, struct list_head *list)
  {
  	return 0;
  }

  static inline int split_huge_page(struct page *page)
  {
  	return 0;
  }

  #define split_huge_page_pmd(__vma, __address, __pmd)	\

  	do { } while (0)
  #define wait_split_huge_page(__anon_vma, __pmd)	\
  	do { } while (0)

  #define split_huge_page_pmd_mm(__mm, __address, __pmd)	\
  	do { } while (0)

  static inline int hugepage_madvise(struct vm_area_struct *vma,
  				   unsigned long *vm_flags, int advice)

  {
  	BUG();
  	return 0;
  }

  static inline void vma_adjust_trans_huge(struct vm_area_struct *vma,
  					 unsigned long start,
  					 unsigned long end,
  					 long adjust_next)
  {
  }

  static inline int pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
  		spinlock_t **ptl)

  {
  	return 0;
  }

  static inline int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
  					unsigned long addr, pmd_t pmd, pmd_t *pmdp)

  {

  	return 0;

  }

  #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
  
  #endif /* _LINUX_HUGE_MM_H */