Subject: Re: [PATCH v2 13/16] powerpc/book3s64/mm: Enable transparent pud hugepage

From: Ritesh Harjani (IBM) <[email-masked]>
Date: Wed, 28 Jun 2023 06:53:58 +0530

"Aneesh Kumar K.V" <[email-masked]> writes:

These are just some minor nits in case you are going to send another
revision.

> This is enabled only with radix translation and 1G hugepage size. This will
> be used with devdax device memory with a namespace alignment of 1G.
>
> Anon transparent hugepage is not supported even though we do have helpers
> checking pud_trans_huge(). We should never find that return true. The only
> expected pte bit combination is _PAGE_PTE | _PAGE_DEVMAP.
>
> Some of the helpers are never expected to get called on hash translation
> and hence is marked to call BUG() in such a case.
>
> Signed-off-by: Aneesh Kumar K.V <[email-masked]>
> ---
>  arch/powerpc/include/asm/book3s/64/pgtable.h  | 156 ++++++++++++++++--
>  arch/powerpc/include/asm/book3s/64/radix.h    |  37 +++++
>  .../include/asm/book3s/64/tlbflush-radix.h    |   2 +
>  arch/powerpc/include/asm/book3s/64/tlbflush.h |   8 +
>  arch/powerpc/mm/book3s64/pgtable.c            |  78 +++++++++
>  arch/powerpc/mm/book3s64/radix_pgtable.c      |  28 ++++
>  arch/powerpc/mm/book3s64/radix_tlb.c          |   7 +
>  arch/powerpc/platforms/Kconfig.cputype        |   1 +
>  include/trace/events/thp.h                    |  17 ++
>  9 files changed, 323 insertions(+), 11 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
> index 4acc9690f599..9a05de007956 100644
> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
> @@ -921,8 +921,29 @@ static inline pud_t pte_pud(pte_t pte)
>  {
>  	return __pud_raw(pte_raw(pte));
>  }
> +
> +static inline pte_t *pudp_ptep(pud_t *pud)
> +{
> +	return (pte_t *)pud;
> +}
> +
> +#define pud_pfn(pud)		pte_pfn(pud_pte(pud))
> +#define pud_dirty(pud)		pte_dirty(pud_pte(pud))
> +#define pud_young(pud)		pte_young(pud_pte(pud))
> +#define pud_mkold(pud)		pte_pud(pte_mkold(pud_pte(pud)))
> +#define pud_wrprotect(pud)	pte_pud(pte_wrprotect(pud_pte(pud)))
> +#define pud_mkdirty(pud)	pte_pud(pte_mkdirty(pud_pte(pud)))
> +#define pud_mkclean(pud)	pte_pud(pte_mkclean(pud_pte(pud)))
> +#define pud_mkyoung(pud)	pte_pud(pte_mkyoung(pud_pte(pud)))
> +#define pud_mkwrite(pud)	pte_pud(pte_mkwrite(pud_pte(pud)))
>  #define pud_write(pud)		pte_write(pud_pte(pud))
>  
> +#ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY
> +#define pud_soft_dirty(pmd)    pte_soft_dirty(pud_pte(pud))
> +#define pud_mksoft_dirty(pmd)  pte_pud(pte_mksoft_dirty(pud_pte(pud)))
> +#define pud_clear_soft_dirty(pmd) pte_pud(pte_clear_soft_dirty(pud_pte(pud)))
> +#endif /* CONFIG_HAVE_ARCH_SOFT_DIRTY */
> +
>  static inline int pud_bad(pud_t pud)
>  {
>  	if (radix_enabled())
> @@ -1115,15 +1136,24 @@ static inline bool pmd_access_permitted(pmd_t pmd, bool write)
>  
>  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
>  extern pmd_t pfn_pmd(unsigned long pfn, pgprot_t pgprot);
> +extern pud_t pfn_pud(unsigned long pfn, pgprot_t pgprot);
>  extern pmd_t mk_pmd(struct page *page, pgprot_t pgprot);
>  extern pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot);
>  extern void set_pmd_at(struct mm_struct *mm, unsigned long addr,
>  		       pmd_t *pmdp, pmd_t pmd);
> +extern void set_pud_at(struct mm_struct *mm, unsigned long addr,
> +		       pud_t *pudp, pud_t pud);
> +
>  static inline void update_mmu_cache_pmd(struct vm_area_struct *vma,
>  					unsigned long addr, pmd_t *pmd)
>  {
>  }
>  
> +static inline void update_mmu_cache_pud(struct vm_area_struct *vma,
> +					unsigned long addr, pud_t *pud)
> +{
> +}
> +
>  extern int hash__has_transparent_hugepage(void);
>  static inline int has_transparent_hugepage(void)
>  {
> @@ -1133,6 +1163,14 @@ static inline int has_transparent_hugepage(void)
>  }
>  #define has_transparent_hugepage has_transparent_hugepage
>  
> +static inline int has_transparent_pud_hugepage(void)
> +{
> +	if (radix_enabled())
> +		return radix__has_transparent_pud_hugepage();
> +	return 0;
> +}
> +#define has_transparent_pud_hugepage has_transparent_pud_hugepage
> +
>  static inline unsigned long
>  pmd_hugepage_update(struct mm_struct *mm, unsigned long addr, pmd_t *pmdp,
>  		    unsigned long clr, unsigned long set)
> @@ -1142,6 +1180,16 @@ pmd_hugepage_update(struct mm_struct *mm, unsigned long addr, pmd_t *pmdp,
>  	return hash__pmd_hugepage_update(mm, addr, pmdp, clr, set);
>  }
>  
> +static inline unsigned long
> +pud_hugepage_update(struct mm_struct *mm, unsigned long addr, pud_t *pudp,
> +		    unsigned long clr, unsigned long set)
> +{
> +	if (radix_enabled())
> +		return radix__pud_hugepage_update(mm, addr, pudp, clr, set);
> +	BUG();
> +	return pud_val(*pudp);
> +}
> +
>  /*
>   * returns true for pmd migration entries, THP, devmap, hugetlb
>   * But compile time dependent on THP config
> @@ -1151,6 +1199,11 @@ static inline int pmd_large(pmd_t pmd)
>  	return !!(pmd_raw(pmd) & cpu_to_be64(_PAGE_PTE));
>  }
>  
> +static inline int pud_large(pud_t pud)
> +{
> +	return !!(pud_raw(pud) & cpu_to_be64(_PAGE_PTE));
> +}
> +
>  /*
>   * For radix we should always find H_PAGE_HASHPTE zero. Hence
>   * the below will work for radix too
> @@ -1166,6 +1219,17 @@ static inline int __pmdp_test_and_clear_young(struct mm_struct *mm,
>  	return ((old & _PAGE_ACCESSED) != 0);
>  }
>  
> +static inline int __pudp_test_and_clear_young(struct mm_struct *mm,
> +					      unsigned long addr, pud_t *pudp)
> +{
> +	unsigned long old;
> +
> +	if ((pud_raw(*pudp) & cpu_to_be64(_PAGE_ACCESSED | H_PAGE_HASHPTE)) == 0)
> +		return 0;
> +	old = pud_hugepage_update(mm, addr, pudp, _PAGE_ACCESSED, 0);
> +	return ((old & _PAGE_ACCESSED) != 0);
> +}
> +
>  #define __HAVE_ARCH_PMDP_SET_WRPROTECT
>  static inline void pmdp_set_wrprotect(struct mm_struct *mm, unsigned long addr,
>  				      pmd_t *pmdp)
> @@ -1174,6 +1238,14 @@ static inline void pmdp_set_wrprotect(struct mm_struct *mm, unsigned long addr,
>  		pmd_hugepage_update(mm, addr, pmdp, _PAGE_WRITE, 0);
>  }
>  
> +#define __HAVE_ARCH_PUDP_SET_WRPROTECT
> +static inline void pudp_set_wrprotect(struct mm_struct *mm, unsigned long addr,
> +				      pud_t *pudp)
> +{
> +	if (pud_write(*pudp))
> +		pud_hugepage_update(mm, addr, pudp, _PAGE_WRITE, 0);
> +}
> +
>  /*
>   * Only returns true for a THP. False for pmd migration entry.
>   * We also need to return true when we come across a pte that
> @@ -1195,6 +1267,17 @@ static inline int pmd_trans_huge(pmd_t pmd)
>  	return hash__pmd_trans_huge(pmd);
>  }
>  
> +static inline int pud_trans_huge(pud_t pud)
> +{
> +	if (!pud_present(pud))
> +		return false;
> +
> +	if (radix_enabled())
> +		return radix__pud_trans_huge(pud);
> +	return 0;
> +}
> +
> +
>  #define __HAVE_ARCH_PMD_SAME
>  static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b)
>  {
> @@ -1203,6 +1286,16 @@ static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b)
>  	return hash__pmd_same(pmd_a, pmd_b);
>  }
>  
> +#define __HAVE_ARCH_PUD_SAME
> +static inline int pud_same(pud_t pud_a, pud_t pud_b)
> +{
> +	if (radix_enabled())
> +		return radix__pud_same(pud_a, pud_b);
> +	BUG();
> +	return 0;
> +}
> +
> +
>  static inline pmd_t __pmd_mkhuge(pmd_t pmd)
>  {
>  	if (radix_enabled())
> @@ -1210,6 +1303,14 @@ static inline pmd_t __pmd_mkhuge(pmd_t pmd)
>  	return hash__pmd_mkhuge(pmd);
>  }
>  
> +static inline pud_t __pud_mkhuge(pud_t pud)
> +{
> +	if (radix_enabled())
> +		return radix__pud_mkhuge(pud);
> +	BUG();
> +	return pud;
> +}
> +
>  /*
>   * pfn_pmd return a pmd_t that can be used as pmd pte entry.
>   */
> @@ -1225,14 +1326,34 @@ static inline pmd_t pmd_mkhuge(pmd_t pmd)
>  	return pmd;
>  }
>  
> +static inline pud_t pud_mkhuge(pud_t pud)
> +{
> +#ifdef CONFIG_DEBUG_VM
> +	if (radix_enabled())
> +		WARN_ON((pud_raw(pud) & cpu_to_be64(_PAGE_PTE)) == 0);
> +	else
> +		WARN_ON(1);
> +#endif
> +	return pud;
> +}
> +
> +
>  #define __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS
>  extern int pmdp_set_access_flags(struct vm_area_struct *vma,
>  				 unsigned long address, pmd_t *pmdp,
>  				 pmd_t entry, int dirty);
> +#define __HAVE_ARCH_PUDP_SET_ACCESS_FLAGS
> +extern int pudp_set_access_flags(struct vm_area_struct *vma,
> +				 unsigned long address, pud_t *pudp,
> +				 pud_t entry, int dirty);
>  
>  #define __HAVE_ARCH_PMDP_TEST_AND_CLEAR_YOUNG
>  extern int pmdp_test_and_clear_young(struct vm_area_struct *vma,
>  				     unsigned long address, pmd_t *pmdp);
> +#define __HAVE_ARCH_PUDP_TEST_AND_CLEAR_YOUNG
> +extern int pudp_test_and_clear_young(struct vm_area_struct *vma,
> +				     unsigned long address, pud_t *pudp);
> +
>  
>  #define __HAVE_ARCH_PMDP_HUGE_GET_AND_CLEAR
>  static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm,
> @@ -1243,6 +1364,16 @@ static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm,
>  	return hash__pmdp_huge_get_and_clear(mm, addr, pmdp);
>  }
>  
> +#define __HAVE_ARCH_PUDP_HUGE_GET_AND_CLEAR
> +static inline pud_t pudp_huge_get_and_clear(struct mm_struct *mm,
> +					    unsigned long addr, pud_t *pudp)
> +{
> +	if (radix_enabled())
> +		return radix__pudp_huge_get_and_clear(mm, addr, pudp);
> +	BUG();
> +	return *pudp;
> +}
> +
>  static inline pmd_t pmdp_collapse_flush(struct vm_area_struct *vma,
>  					unsigned long address, pmd_t *pmdp)
>  {
> @@ -1257,6 +1388,11 @@ pmd_t pmdp_huge_get_and_clear_full(struct vm_area_struct *vma,
>  				   unsigned long addr,
>  				   pmd_t *pmdp, int full);
>  
> +#define __HAVE_ARCH_PUDP_HUGE_GET_AND_CLEAR_FULL
> +pud_t pudp_huge_get_and_clear_full(struct vm_area_struct *vma,
> +				   unsigned long addr,
> +				   pud_t *pudp, int full);
> +
>  #define __HAVE_ARCH_PGTABLE_DEPOSIT
>  static inline void pgtable_trans_huge_deposit(struct mm_struct *mm,
>  					      pmd_t *pmdp, pgtable_t pgtable)
> @@ -1305,6 +1441,14 @@ static inline pmd_t pmd_mkdevmap(pmd_t pmd)
>  	return hash__pmd_mkdevmap(pmd);
>  }
>  
> +static inline pud_t pud_mkdevmap(pud_t pud)
> +{
> +	if (radix_enabled())
> +		return radix__pud_mkdevmap(pud);
> +	BUG();
> +	return pud;
> +}
> +
>  static inline int pmd_devmap(pmd_t pmd)
>  {
>  	return pte_devmap(pmd_pte(pmd));
> @@ -1312,7 +1456,7 @@ static inline int pmd_devmap(pmd_t pmd)
>  
>  static inline int pud_devmap(pud_t pud)
>  {
> -	return 0;
> +	return pte_devmap(pud_pte(pud));
>  }
>  
>  static inline int pgd_devmap(pgd_t pgd)
> @@ -1321,16 +1465,6 @@ static inline int pgd_devmap(pgd_t pgd)
>  }
>  #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
>  
> -static inline int pud_pfn(pud_t pud)
> -{
> -	/*
> -	 * Currently all calls to pud_pfn() are gated around a pud_devmap()
> -	 * check so this should never be used. If it grows another user we
> -	 * want to know about it.
> -	 */
> -	BUILD_BUG();
> -	return 0;
> -}
>  #define __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION
>  pte_t ptep_modify_prot_start(struct vm_area_struct *, unsigned long, pte_t *);
>  void ptep_modify_prot_commit(struct vm_area_struct *, unsigned long,
> diff --git a/arch/powerpc/include/asm/book3s/64/radix.h b/arch/powerpc/include/asm/book3s/64/radix.h
> index 686001eda936..8cdff5a05011 100644
> --- a/arch/powerpc/include/asm/book3s/64/radix.h
> +++ b/arch/powerpc/include/asm/book3s/64/radix.h
> @@ -250,6 +250,10 @@ static inline int radix__pud_bad(pud_t pud)
>  	return !!(pud_val(pud) & RADIX_PUD_BAD_BITS);
>  }
>  
> +static inline int radix__pud_same(pud_t pud_a, pud_t pud_b)
> +{
> +	return ((pud_raw(pud_a) ^ pud_raw(pud_b)) == 0);
> +}
>  
>  static inline int radix__p4d_bad(p4d_t p4d)
>  {
> @@ -268,9 +272,22 @@ static inline pmd_t radix__pmd_mkhuge(pmd_t pmd)
>  	return __pmd(pmd_val(pmd) | _PAGE_PTE);
>  }
>  
> +static inline int radix__pud_trans_huge(pud_t pud)
> +{
> +	return (pud_val(pud) & (_PAGE_PTE | _PAGE_DEVMAP)) == _PAGE_PTE;
> +}
> +
> +static inline pud_t radix__pud_mkhuge(pud_t pud)
> +{
> +	return __pud(pud_val(pud) | _PAGE_PTE);
> +}
> +
>  extern unsigned long radix__pmd_hugepage_update(struct mm_struct *mm, unsigned long addr,
>  					  pmd_t *pmdp, unsigned long clr,
>  					  unsigned long set);
> +extern unsigned long radix__pud_hugepage_update(struct mm_struct *mm, unsigned long addr,
> +						pud_t *pudp, unsigned long clr,
> +						unsigned long set);
>  extern pmd_t radix__pmdp_collapse_flush(struct vm_area_struct *vma,
>  				  unsigned long address, pmd_t *pmdp);
>  extern void radix__pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
> @@ -278,6 +295,9 @@ extern void radix__pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
>  extern pgtable_t radix__pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp);
>  extern pmd_t radix__pmdp_huge_get_and_clear(struct mm_struct *mm,
>  				      unsigned long addr, pmd_t *pmdp);
> +pud_t radix__pudp_huge_get_and_clear(struct mm_struct *mm,
> +				     unsigned long addr, pud_t *pudp);
> +
>  static inline int radix__has_transparent_hugepage(void)
>  {
>  	/* For radix 2M at PMD level means thp */
> @@ -285,6 +305,14 @@ static inline int radix__has_transparent_hugepage(void)
>  		return 1;
>  	return 0;
>  }
> +
> +static inline int radix__has_transparent_pud_hugepage(void)
> +{
> +	/* For radix 1G at PUD level means pud hugepage support */
> +	if (mmu_psize_defs[MMU_PAGE_1G].shift == PUD_SHIFT)
> +		return 1;
> +	return 0;
> +}
>  #endif
>  
>  static inline pmd_t radix__pmd_mkdevmap(pmd_t pmd)
> @@ -292,9 +320,18 @@ static inline pmd_t radix__pmd_mkdevmap(pmd_t pmd)
>  	return __pmd(pmd_val(pmd) | (_PAGE_PTE | _PAGE_DEVMAP));
>  }
>  
> +static inline pud_t radix__pud_mkdevmap(pud_t pud)
> +{
> +	return __pud(pud_val(pud) | (_PAGE_PTE | _PAGE_DEVMAP));
> +}
> +
> +struct vmem_altmap;
> +struct dev_pagemap;

Minor nit.
I guess this struct dev_pagemap is meant to be added in a later patch.

>  extern int __meminit radix__vmemmap_create_mapping(unsigned long start,
>  					     unsigned long page_size,
>  					     unsigned long phys);
> +int __meminit radix__vmemmap_populate(unsigned long start, unsigned long end,
> +				      int node, struct vmem_altmap *altmap);
>  extern void radix__vmemmap_remove_mapping(unsigned long start,
>  				    unsigned long page_size);
>  
> diff --git a/arch/powerpc/include/asm/book3s/64/tlbflush-radix.h b/arch/powerpc/include/asm/book3s/64/tlbflush-radix.h
> index 77797a2a82eb..a38542259fab 100644
> --- a/arch/powerpc/include/asm/book3s/64/tlbflush-radix.h
> +++ b/arch/powerpc/include/asm/book3s/64/tlbflush-radix.h
> @@ -68,6 +68,8 @@ void radix__flush_tlb_pwc_range_psize(struct mm_struct *mm, unsigned long start,
>  				      unsigned long end, int psize);
>  extern void radix__flush_pmd_tlb_range(struct vm_area_struct *vma,
>  				       unsigned long start, unsigned long end);
> +extern void radix__flush_pud_tlb_range(struct vm_area_struct *vma,
> +				       unsigned long start, unsigned long end);
>  extern void radix__flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
>  			    unsigned long end);
>  extern void radix__flush_tlb_kernel_range(unsigned long start, unsigned long end);
> diff --git a/arch/powerpc/include/asm/book3s/64/tlbflush.h b/arch/powerpc/include/asm/book3s/64/tlbflush.h
> index 0d0c1447ecf0..a01c20a8fbf7 100644
> --- a/arch/powerpc/include/asm/book3s/64/tlbflush.h
> +++ b/arch/powerpc/include/asm/book3s/64/tlbflush.h
> @@ -50,6 +50,14 @@ static inline void flush_pmd_tlb_range(struct vm_area_struct *vma,
>  		radix__flush_pmd_tlb_range(vma, start, end);
>  }
>  
> +#define __HAVE_ARCH_FLUSH_PUD_TLB_RANGE
> +static inline void flush_pud_tlb_range(struct vm_area_struct *vma,
> +				       unsigned long start, unsigned long end)
> +{
> +	if (radix_enabled())
> +		radix__flush_pud_tlb_range(vma, start, end);
> +}
> +
>  #define __HAVE_ARCH_FLUSH_HUGETLB_TLB_RANGE
>  static inline void flush_hugetlb_tlb_range(struct vm_area_struct *vma,
>  					   unsigned long start,
> diff --git a/arch/powerpc/mm/book3s64/pgtable.c b/arch/powerpc/mm/book3s64/pgtable.c
> index 85c84e89e3ea..9e5f01a1738c 100644
> --- a/arch/powerpc/mm/book3s64/pgtable.c
> +++ b/arch/powerpc/mm/book3s64/pgtable.c
> @@ -64,11 +64,39 @@ int pmdp_set_access_flags(struct vm_area_struct *vma, unsigned long address,
>  	return changed;
>  }
>  
> +int pudp_set_access_flags(struct vm_area_struct *vma, unsigned long address,
> +			  pud_t *pudp, pud_t entry, int dirty)
> +{
> +	int changed;
> +#ifdef CONFIG_DEBUG_VM
> +	WARN_ON(!pud_devmap(*pudp));

just a query -
for pmdp_set_access_flags() we had
WARN_ON(!pmd_trans_huge(*pmdp) && !pmd_devmap(*pmdp));

so why don't we require the same check here?

> +	assert_spin_locked(pud_lockptr(vma->vm_mm, pudp));
> +#endif
> +	changed = !pud_same(*(pudp), entry);
> +	if (changed) {
> +		/*
> +		 * We can use MMU_PAGE_2M here, because only radix

s/MMU_PAGE_2M/MMY_PAGE_1G

> +		 * path look at the psize.
> +		 */
> +		__ptep_set_access_flags(vma, pudp_ptep(pudp),
> +					pud_pte(entry), address, MMU_PAGE_1G);
> +	}
> +	return changed;
> +}
> +
> +
>  int pmdp_test_and_clear_young(struct vm_area_struct *vma,
>  			      unsigned long address, pmd_t *pmdp)
>  {
>  	return __pmdp_test_and_clear_young(vma->vm_mm, address, pmdp);
>  }
> +
> +int pudp_test_and_clear_young(struct vm_area_struct *vma,
> +			      unsigned long address, pud_t *pudp)
> +{
> +	return __pudp_test_and_clear_young(vma->vm_mm, address, pudp);
> +}
> +
>  /*
>   * set a new huge pmd. We should not be called for updating
>   * an existing pmd entry. That should go via pmd_hugepage_update.
> @@ -90,6 +118,23 @@ void set_pmd_at(struct mm_struct *mm, unsigned long addr,
>  	return set_pte_at(mm, addr, pmdp_ptep(pmdp), pmd_pte(pmd));
>  }
>  
> +void set_pud_at(struct mm_struct *mm, unsigned long addr,
> +		pud_t *pudp, pud_t pud)
> +{
> +#ifdef CONFIG_DEBUG_VM
> +	/*
> +	 * Make sure hardware valid bit is not set. We don't do
> +	 * tlb flush for this update.
> +	 */
> +
> +	WARN_ON(pte_hw_valid(pud_pte(*pudp)));

For set_pmd_at() we had
WARN_ON(pte_hw_valid(pmd_pte(*pmdp)) && !pte_protnone(pmd_pte(*pmdp)));

Could you please help me understand why is it different for set_pud_at()

> +	assert_spin_locked(pud_lockptr(mm, pudp));
> +	WARN_ON(!(pud_large(pud)));
> +#endif
> +	trace_hugepage_set_pud(addr, pud_val(pud));
> +	return set_pte_at(mm, addr, pudp_ptep(pudp), pud_pte(pud));
> +}
> +
>  static void do_serialize(void *arg)
>  {
>  	/* We've taken the IPI, so try to trim the mask while here */
> @@ -147,11 +192,35 @@ pmd_t pmdp_huge_get_and_clear_full(struct vm_area_struct *vma,
>  	return pmd;
>  }
>  
> +pud_t pudp_huge_get_and_clear_full(struct vm_area_struct *vma,
> +				   unsigned long addr, pud_t *pudp, int full)
> +{
> +	pud_t pud;
> +
> +	VM_BUG_ON(addr & ~HPAGE_PMD_MASK);
> +	VM_BUG_ON((pud_present(*pudp) && !pud_devmap(*pudp)) ||
> +		  !pud_present(*pudp));
> +	pud = pudp_huge_get_and_clear(vma->vm_mm, addr, pudp);
> +	/*
> +	 * if it not a fullmm flush, then we can possibly end up converting
> +	 * this PMD pte entry to a regular level 0 PTE by a parallel page fault.
> +	 * Make sure we flush the tlb in this case.
> +	 */
> +	if (!full)
> +		flush_pud_tlb_range(vma, addr, addr + HPAGE_PUD_SIZE);
> +	return pud;
> +}
> +
>  static pmd_t pmd_set_protbits(pmd_t pmd, pgprot_t pgprot)
>  {
>  	return __pmd(pmd_val(pmd) | pgprot_val(pgprot));
>  }
>  
> +static pud_t pud_set_protbits(pud_t pud, pgprot_t pgprot)
> +{
> +	return __pud(pud_val(pud) | pgprot_val(pgprot));
> +}
> +
>  /*
>   * At some point we should be able to get rid of
>   * pmd_mkhuge() and mk_huge_pmd() when we update all the
> @@ -166,6 +235,15 @@ pmd_t pfn_pmd(unsigned long pfn, pgprot_t pgprot)
>  	return __pmd_mkhuge(pmd_set_protbits(__pmd(pmdv), pgprot));
>  }
>  
> +pud_t pfn_pud(unsigned long pfn, pgprot_t pgprot)
> +{
> +	unsigned long pudv;
> +
> +	pudv = (pfn << PAGE_SHIFT) & PTE_RPN_MASK;
> +
> +	return __pud_mkhuge(pud_set_protbits(__pud(pudv), pgprot));
> +}
> +
>  pmd_t mk_pmd(struct page *page, pgprot_t pgprot)
>  {
>  	return pfn_pmd(page_to_pfn(page), pgprot);
> diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c
> index 76f6a1f3b9d8..d7e2dd3d4add 100644
> --- a/arch/powerpc/mm/book3s64/radix_pgtable.c
> +++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
> @@ -965,6 +965,23 @@ unsigned long radix__pmd_hugepage_update(struct mm_struct *mm, unsigned long add
>  	return old;
>  }
>  
> +unsigned long radix__pud_hugepage_update(struct mm_struct *mm, unsigned long addr,
> +					 pud_t *pudp, unsigned long clr,
> +					 unsigned long set)
> +{
> +	unsigned long old;
> +
> +#ifdef CONFIG_DEBUG_VM
> +	WARN_ON(!pud_devmap(*pudp));
> +	assert_spin_locked(pud_lockptr(mm, pudp));
> +#endif
> +
> +	old = radix__pte_update(mm, addr, pudp_ptep(pudp), clr, set, 1);
> +	trace_hugepage_update(addr, old, clr, set);

Here, we are using the same trace event for both pmd and pud update.
See the comment in the end.

> +
> +	return old;
> +}
> +
>  pmd_t radix__pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long address,
>  			pmd_t *pmdp)
>  
> @@ -1041,6 +1058,17 @@ pmd_t radix__pmdp_huge_get_and_clear(struct mm_struct *mm,
>  	return old_pmd;
>  }
>  
> +pud_t radix__pudp_huge_get_and_clear(struct mm_struct *mm,
> +				     unsigned long addr, pud_t *pudp)
> +{
> +	pud_t old_pud;
> +	unsigned long old;
> +
> +	old = radix__pud_hugepage_update(mm, addr, pudp, ~0UL, 0);
> +	old_pud = __pud(old);
> +	return old_pud;
> +}
> +
>  #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
>  
>  void radix__ptep_set_access_flags(struct vm_area_struct *vma, pte_t *ptep,
> diff --git a/arch/powerpc/mm/book3s64/radix_tlb.c b/arch/powerpc/mm/book3s64/radix_tlb.c
> index ce804b7bf84e..a18f7d2c9f63 100644
> --- a/arch/powerpc/mm/book3s64/radix_tlb.c
> +++ b/arch/powerpc/mm/book3s64/radix_tlb.c
> @@ -1453,6 +1453,13 @@ void radix__flush_pmd_tlb_range(struct vm_area_struct *vma,
>  }
>  EXPORT_SYMBOL(radix__flush_pmd_tlb_range);
>  
> +void radix__flush_pud_tlb_range(struct vm_area_struct *vma,
> +				unsigned long start, unsigned long end)
> +{
> +	radix__flush_tlb_range_psize(vma->vm_mm, start, end, MMU_PAGE_1G);
> +}
> +EXPORT_SYMBOL(radix__flush_pud_tlb_range);
> +
>  void radix__flush_tlb_all(void)
>  {
>  	unsigned long rb,prs,r,rs;
> diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
> index 45fd975ef521..340b86ef7284 100644
> --- a/arch/powerpc/platforms/Kconfig.cputype
> +++ b/arch/powerpc/platforms/Kconfig.cputype
> @@ -94,6 +94,7 @@ config PPC_BOOK3S_64
>  	select PPC_FPU
>  	select PPC_HAVE_PMU_SUPPORT
>  	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
> +	select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
>  	select ARCH_ENABLE_HUGEPAGE_MIGRATION if HUGETLB_PAGE && MIGRATION
>  	select ARCH_ENABLE_SPLIT_PMD_PTLOCK
>  	select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE
> diff --git a/include/trace/events/thp.h b/include/trace/events/thp.h
> index 202b3e3e67ff..a919d943d106 100644
> --- a/include/trace/events/thp.h
> +++ b/include/trace/events/thp.h
> @@ -25,6 +25,23 @@ TRACE_EVENT(hugepage_set_pmd,
>  	    TP_printk("Set pmd with 0x%lx with 0x%lx", __entry->addr, __entry->pmd)
>  );
>  
> +TRACE_EVENT(hugepage_set_pud,

Given we have trace_hugepage_set_pud and trace_hugepage_set_pmd, doing
the exact same thing, we can as well have a
DECLARE_EVENT_CLASS(hugepage_set) and then DEFINE_EVENT using this event class.

> +
> +	    TP_PROTO(unsigned long addr, unsigned long pud),
> +	    TP_ARGS(addr, pud),
> +	    TP_STRUCT__entry(
> +		    __field(unsigned long, addr)
> +		    __field(unsigned long, pud)
> +			    ),
> +
> +	    TP_fast_assign(
> +		    __entry->addr = addr;
> +		    __entry->pud = pud;
> +		    ),
> +
> +	    TP_printk("Set pud with 0x%lx with 0x%lx", __entry->addr, __entry->pud)
> +	);
> +
>  
>  TRACE_EVENT(hugepage_update,

Same here. We can have a DECLARE_EVENT_CLASS(hugepage_update) and then
DEFINE_EVENT for hugepage_update_pmd and hugepage_update_pud.

-ritesh