Re: [PATCH v3 07/10] treewide: rename has_transparent_hugepage() to arch_has_pmd_leaves()

Luiz Capitulino
2026-04-09T19:43:29Z

On 2026-04-09 11:41, Zi Yan wrote:
> On 8 Apr 2026, at 16:23, Luiz Capitulino wrote:
>
>> Now that all the has_transparent_hugepage() callers have been converted
>> to pgtable_has_pmd_leaves(), rename has_transparent_hugepage() to
>> arch_has_pmd_leaves() since that's what the helper checks for.
>>
>> arch_has_pmd_leaves() is supposed to be called only by
>> init_arch_has_pmd_leaves(). The remaining exception is hugepage_init()
>> which will be converted in a future commit.
>>
>> Signed-off-by: Luiz Capitulino <luizcap@redhat.com>
>> ---
>> arch/mips/include/asm/pgtable.h | 4 ++--
>> arch/mips/mm/tlb-r4k.c | 4 ++--
>> arch/powerpc/include/asm/book3s/64/hash-4k.h | 2 +-
>> arch/powerpc/include/asm/book3s/64/hash-64k.h | 2 +-
>> arch/powerpc/include/asm/book3s/64/pgtable.h | 10 +++++-----
>> arch/powerpc/include/asm/book3s/64/radix.h | 2 +-
>> arch/powerpc/mm/book3s64/hash_pgtable.c | 4 ++--
>> arch/s390/include/asm/pgtable.h | 4 ++--
>> arch/x86/include/asm/pgtable.h | 4 ++--
>> include/linux/pgtable.h | 4 ++--
>> mm/huge_memory.c | 2 +-
>> mm/memory.c | 2 +-
>> 12 files changed, 22 insertions(+), 22 deletions(-)
>>
>> diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
>> index fa7b935f947c..a97b788315e2 100644
>> --- a/arch/mips/include/asm/pgtable.h
>> +++ b/arch/mips/include/asm/pgtable.h
>> @@ -615,8 +615,8 @@ unsigned long io_remap_pfn_range_pfn(unsigned long pfn, unsigned long size);
>> /* We don't have hardware dirty/accessed bits, generic_pmdp_establish is fine.*/
>> #define pmdp_establish generic_pmdp_establish
>>
>> -#define has_transparent_hugepage has_transparent_hugepage
>> -extern int has_transparent_hugepage(void);
>> +#define arch_has_pmd_leaves arch_has_pmd_leaves
>> +extern int arch_has_pmd_leaves(void);
>>
>> static inline int pmd_trans_huge(pmd_t pmd)
>> {
>> diff --git a/arch/mips/mm/tlb-r4k.c b/arch/mips/mm/tlb-r4k.c
>> index 24fe85fa169d..c423b5784337 100644
>> --- a/arch/mips/mm/tlb-r4k.c
>> +++ b/arch/mips/mm/tlb-r4k.c
>> @@ -434,7 +434,7 @@ void add_wired_entry(unsigned long entrylo0, unsigned long entrylo1,
>>
>> #ifdef CONFIG_TRANSPARENT_HUGEPAGE
>>
>> -int has_transparent_hugepage(void)
>> +int arch_has_pmd_leaves(void)
>> {
>> static unsigned int mask = -1;
>>
>> @@ -450,7 +450,7 @@ int has_transparent_hugepage(void)
>> }
>> return mask == PM_HUGE_MASK;
>> }
>> -EXPORT_SYMBOL(has_transparent_hugepage);
>> +EXPORT_SYMBOL(arch_has_pmd_leaves);
>>
>> #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
>>
>> diff --git a/arch/powerpc/include/asm/book3s/64/hash-4k.h b/arch/powerpc/include/asm/book3s/64/hash-4k.h
>> index 8e5bd9902bed..6744c2287199 100644
>> --- a/arch/powerpc/include/asm/book3s/64/hash-4k.h
>> +++ b/arch/powerpc/include/asm/book3s/64/hash-4k.h
>> @@ -165,7 +165,7 @@ extern void hash__pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
>> extern pgtable_t hash__pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp);
>> extern pmd_t hash__pmdp_huge_get_and_clear(struct mm_struct *mm,
>> unsigned long addr, pmd_t *pmdp);
>> -extern int hash__has_transparent_hugepage(void);
>> +extern int hash__arch_has_pmd_leaves(void);
>> #endif
>>
>> #endif /* !__ASSEMBLER__ */
>> diff --git a/arch/powerpc/include/asm/book3s/64/hash-64k.h b/arch/powerpc/include/asm/book3s/64/hash-64k.h
>> index 7deb3a66890b..9392aba5e5dc 100644
>> --- a/arch/powerpc/include/asm/book3s/64/hash-64k.h
>> +++ b/arch/powerpc/include/asm/book3s/64/hash-64k.h
>> @@ -278,7 +278,7 @@ extern void hash__pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
>> extern pgtable_t hash__pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp);
>> extern pmd_t hash__pmdp_huge_get_and_clear(struct mm_struct *mm,
>> unsigned long addr, pmd_t *pmdp);
>> -extern int hash__has_transparent_hugepage(void);
>> +extern int hash__arch_has_pmd_leaves(void);
>> #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
>>
>> #endif /* __ASSEMBLER__ */
>> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
>> index 1a91762b455d..e4d9b884af5c 100644
>> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
>> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
>> @@ -1121,14 +1121,14 @@ static inline void update_mmu_cache_pud(struct vm_area_struct *vma,
>> {
>> }
>>
>> -extern int hash__has_transparent_hugepage(void);
>> -static inline int has_transparent_hugepage(void)
>> +extern int hash__arch_has_pmd_leaves(void);
>> +static inline int arch_has_pmd_leaves(void)
>> {
>> if (radix_enabled())
>> - return radix__has_transparent_hugepage();
>> - return hash__has_transparent_hugepage();
>> + return radix__arch_has_pmd_leaves();
>> + return hash__arch_has_pmd_leaves();
>> }
>> -#define has_transparent_hugepage has_transparent_hugepage
>> +#define arch_has_pmd_leaves arch_has_pmd_leaves
>>
>> static inline int has_transparent_pud_hugepage(void)
>> {
>> diff --git a/arch/powerpc/include/asm/book3s/64/radix.h b/arch/powerpc/include/asm/book3s/64/radix.h
>> index da954e779744..c884a119cbd9 100644
>> --- a/arch/powerpc/include/asm/book3s/64/radix.h
>> +++ b/arch/powerpc/include/asm/book3s/64/radix.h
>> @@ -298,7 +298,7 @@ extern pmd_t radix__pmdp_huge_get_and_clear(struct mm_struct *mm,
>> 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)
>> +static inline int radix__arch_has_pmd_leaves(void)
>> {
>> /* For radix 2M at PMD level means thp */
>> if (mmu_psize_defs[MMU_PAGE_2M].shift == PMD_SHIFT)
>> diff --git a/arch/powerpc/mm/book3s64/hash_pgtable.c b/arch/powerpc/mm/book3s64/hash_pgtable.c
>> index ac2a24d15d2e..f7933c52cca9 100644
>> --- a/arch/powerpc/mm/book3s64/hash_pgtable.c
>> +++ b/arch/powerpc/mm/book3s64/hash_pgtable.c
>> @@ -370,7 +370,7 @@ pmd_t hash__pmdp_huge_get_and_clear(struct mm_struct *mm,
>> return old_pmd;
>> }
>>
>> -int hash__has_transparent_hugepage(void)
>> +int hash__arch_has_pmd_leaves(void)
>> {
>>
>> if (!mmu_has_feature(MMU_FTR_16M_PAGE))
>> @@ -399,7 +399,7 @@ int hash__has_transparent_hugepage(void)
>>
>> return 1;
>> }
>> -EXPORT_SYMBOL_GPL(hash__has_transparent_hugepage);
>> +EXPORT_SYMBOL_GPL(hash__arch_has_pmd_leaves);
>>
>> #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
>>
>> diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
>> index 1c3c3be93be9..e638d914fbad 100644
>> --- a/arch/s390/include/asm/pgtable.h
>> +++ b/arch/s390/include/asm/pgtable.h
>> @@ -1776,8 +1776,8 @@ static inline int pmd_trans_huge(pmd_t pmd)
>> return pmd_leaf(pmd);
>> }
>>
>> -#define has_transparent_hugepage has_transparent_hugepage
>> -static inline int has_transparent_hugepage(void)
>> +#define arch_has_pmd_leaves arch_has_pmd_leaves
>> +static inline int arch_has_pmd_leaves(void)
>> {
>> return cpu_has_edat1() ? 1 : 0;
>> }
>> diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
>> index 1662c5a8f445..8fe95270b713 100644
>> --- a/arch/x86/include/asm/pgtable.h
>> +++ b/arch/x86/include/asm/pgtable.h
>> @@ -314,8 +314,8 @@ static inline int pud_trans_huge(pud_t pud)
>> }
>> #endif
>>
>> -#define has_transparent_hugepage has_transparent_hugepage
>> -static inline int has_transparent_hugepage(void)
>> +#define arch_has_pmd_leaves arch_has_pmd_leaves
>> +static inline int arch_has_pmd_leaves(void)
>> {
>> return boot_cpu_has(X86_FEATURE_PSE);
>> }
>> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
>> index c4c5282f795c..4b52a3abeab5 100644
>> --- a/include/linux/pgtable.h
>> +++ b/include/linux/pgtable.h
>> @@ -2222,8 +2222,8 @@ static inline void __init init_arch_has_pmd_leaves(void) { }
>> #endif
>> #endif
>>
>> -#ifndef has_transparent_hugepage
>> -#define has_transparent_hugepage() IS_BUILTIN(CONFIG_TRANSPARENT_HUGEPAGE)
>> +#ifndef arch_has_pmd_leaves
>> +#define arch_has_pmd_leaves() IS_BUILTIN(CONFIG_TRANSPARENT_HUGEPAGE)
>
> Should this be
> #define arch_has_pmd_leaves() 1
> ?
>
> Since all has_transparent_hugepage() is converted
> to IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && pgtable_has_pmd_leaves()
> and pgtable_has_pmd_leaves() is basically arch_has_pmd_leaves().
> The IS_ENABLED() is the same as IS_BUILTIN() here.
>
> Before this patch, if an arch does not define has_transparent_hugepage,
> has_transparent_hugepage() basically means the arch supports PMD leaves
> and software controls the availability of THP. Now you rename it to
> arch_has_pmd_leaves() and setting it to 1 reflects its actual semantics.

Yes, you're right that the intended future semantics is: if an arch
doesn't define arch_has_pmd_leaves() then the kernel assumes it supports
PMD pages.

I originally kept arch_has_pmd_leaves() tied to THP because I was afraid
of breaking the current callers who want to use PMD pages with THP. But,
as you say, they should all be checking for
IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) now.

I'll look into implementing your suggestion for v4.