Re: [PATCH 4/6] mm: change to return bool for pmdp_clear_flush_young()

["Lorenzo Stoakes (Oracle)" <ljs@kernel.org>]

On Thu, Mar 19, 2026 at 11:24:03AM +0800, Baolin Wang wrote:
> The pmdp_clear_flush_young() is used to clear the young flag and flush the
> TLB, returning whether the young flag was set for this PMD entry. Change
> the return type to bool to make the intention clearer.
>
> Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>

Some nits, but otherwise LGTM, so:

Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>

> ---
>  arch/s390/include/asm/pgtable.h |  4 ++--
>  arch/x86/include/asm/pgtable.h  |  4 ++--
>  arch/x86/mm/pgtable.c           |  6 +++---
>  include/linux/pgtable.h         | 10 +++++-----
>  mm/pgtable-generic.c            |  7 ++++---
>  5 files changed, 16 insertions(+), 15 deletions(-)
>
> diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
> index 1f5efb7be71d..90bba85ca4b8 100644
> --- a/arch/s390/include/asm/pgtable.h
> +++ b/arch/s390/include/asm/pgtable.h
> @@ -1693,8 +1693,8 @@ static inline bool pmdp_test_and_clear_young(struct vm_area_struct *vma,
>  }
>
>  #define __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH
> -static inline int pmdp_clear_flush_young(struct vm_area_struct *vma,
> -					 unsigned long addr, pmd_t *pmdp)
> +static inline bool pmdp_clear_flush_young(struct vm_area_struct *vma,
> +					  unsigned long addr, pmd_t *pmdp)

Same indentation comment as with other patches, 2 tabs you know the drill :)
applies to all such in this patch.

>  {
>  	VM_BUG_ON(addr & ~HPAGE_MASK);
>  	return pmdp_test_and_clear_young(vma, addr, pmdp);
> diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
> index bd02ee730a23..f9439449c9bd 100644
> --- a/arch/x86/include/asm/pgtable.h
> +++ b/arch/x86/include/asm/pgtable.h
> @@ -1301,8 +1301,8 @@ extern int pudp_test_and_clear_young(struct vm_area_struct *vma,
>  				     unsigned long addr, pud_t *pudp);
>
>  #define __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH
> -extern int pmdp_clear_flush_young(struct vm_area_struct *vma,
> -				  unsigned long address, pmd_t *pmdp);
> +extern bool pmdp_clear_flush_young(struct vm_area_struct *vma,
> +				   unsigned long address, pmd_t *pmdp);

Drop the extern please!

>
>
>  #define __HAVE_ARCH_PMDP_HUGE_GET_AND_CLEAR
> diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
> index 10a5e0b2be36..8c336edf0e65 100644
> --- a/arch/x86/mm/pgtable.c
> +++ b/arch/x86/mm/pgtable.c
> @@ -503,10 +503,10 @@ bool ptep_clear_flush_young(struct vm_area_struct *vma,
>  }
>
>  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> -int pmdp_clear_flush_young(struct vm_area_struct *vma,
> -			   unsigned long address, pmd_t *pmdp)
> +bool pmdp_clear_flush_young(struct vm_area_struct *vma,
> +			    unsigned long address, pmd_t *pmdp)
>  {
> -	int young;
> +	bool young;
>
>  	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
>
> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> index e53220b0a9a3..8b8838f19af3 100644
> --- a/include/linux/pgtable.h
> +++ b/include/linux/pgtable.h
> @@ -536,18 +536,18 @@ bool ptep_clear_flush_young(struct vm_area_struct *vma,
>
>  #ifndef __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH
>  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> -extern int pmdp_clear_flush_young(struct vm_area_struct *vma,
> -				  unsigned long address, pmd_t *pmdp);
> +bool pmdp_clear_flush_young(struct vm_area_struct *vma,
> +		unsigned long address, pmd_t *pmdp);

Ahh! Here you drop the extern :) AND use 2 tabs :)) thanks!

>  #else
>  /*
>   * Despite relevant to THP only, this API is called from generic rmap code
>   * under PageTransHuge(), hence needs a dummy implementation for !THP
>   */
> -static inline int pmdp_clear_flush_young(struct vm_area_struct *vma,
> -					 unsigned long address, pmd_t *pmdp)
> +static inline bool pmdp_clear_flush_young(struct vm_area_struct *vma,
> +		unsigned long address, pmd_t *pmdp)
>  {
>  	BUILD_BUG();
> -	return 0;
> +	return false;
>  }
>  #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
>  #endif
> diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
> index db0ee918b08a..b91b1a98029c 100644
> --- a/mm/pgtable-generic.c
> +++ b/mm/pgtable-generic.c
> @@ -124,10 +124,11 @@ int pmdp_set_access_flags(struct vm_area_struct *vma,
>  #endif
>
>  #ifndef __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH
> -int pmdp_clear_flush_young(struct vm_area_struct *vma,
> -			   unsigned long address, pmd_t *pmdp)
> +bool pmdp_clear_flush_young(struct vm_area_struct *vma,
> +		unsigned long address, pmd_t *pmdp)
>  {
> -	int young;
> +	bool young;
> +
>  	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
>  	young = pmdp_test_and_clear_young(vma, address, pmdp);
>  	if (young)
> --
> 2.47.3
>