Subject: Re: [PATCH] mm: Move p?d_alloc_track to separate header file

From: Christophe Leroy <[email-masked]>
Date: Tue, 9 Jun 2020 17:24:14 +0200

Le 09/06/2020 à 14:05, Joerg Roedel a écrit :
> From: Joerg Roedel <[email-masked]>
> 
> The functions are only used in two source files, so there is no need
> for them to be in the global <linux/mm.h> header. Move them to the new
> <linux/pgalloc-track.h> header and include it only where needed.

Do you mean we will now create a new header file for any new couple on 
functions based on where they are used ?

Can you explain why this change is needed or is a plus ?

Christophe

> 
> Signed-off-by: Joerg Roedel <[email-masked]>
> ---
>   include/linux/mm.h            | 45 -------------------------------
>   include/linux/pgalloc-track.h | 51 +++++++++++++++++++++++++++++++++++
>   lib/ioremap.c                 |  1 +
>   mm/vmalloc.c                  |  1 +
>   4 files changed, 53 insertions(+), 45 deletions(-)
>   create mode 100644 include/linux/pgalloc-track.h
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 9d6042178ca7..22d8b2a2c9bc 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2092,51 +2092,11 @@ static inline pud_t *pud_alloc(struct mm_struct *mm, p4d_t *p4d,
>   		NULL : pud_offset(p4d, address);
>   }
>   
> -static inline p4d_t *p4d_alloc_track(struct mm_struct *mm, pgd_t *pgd,
> -				     unsigned long address,
> -				     pgtbl_mod_mask *mod_mask)
> -
> -{
> -	if (unlikely(pgd_none(*pgd))) {
> -		if (__p4d_alloc(mm, pgd, address))
> -			return NULL;
> -		*mod_mask |= PGTBL_PGD_MODIFIED;
> -	}
> -
> -	return p4d_offset(pgd, address);
> -}
> -
> -static inline pud_t *pud_alloc_track(struct mm_struct *mm, p4d_t *p4d,
> -				     unsigned long address,
> -				     pgtbl_mod_mask *mod_mask)
> -{
> -	if (unlikely(p4d_none(*p4d))) {
> -		if (__pud_alloc(mm, p4d, address))
> -			return NULL;
> -		*mod_mask |= PGTBL_P4D_MODIFIED;
> -	}
> -
> -	return pud_offset(p4d, address);
> -}
> -
>   static inline pmd_t *pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
>   {
>   	return (unlikely(pud_none(*pud)) && __pmd_alloc(mm, pud, address))?
>   		NULL: pmd_offset(pud, address);
>   }
> -
> -static inline pmd_t *pmd_alloc_track(struct mm_struct *mm, pud_t *pud,
> -				     unsigned long address,
> -				     pgtbl_mod_mask *mod_mask)
> -{
> -	if (unlikely(pud_none(*pud))) {
> -		if (__pmd_alloc(mm, pud, address))
> -			return NULL;
> -		*mod_mask |= PGTBL_PUD_MODIFIED;
> -	}
> -
> -	return pmd_offset(pud, address);
> -}
>   #endif /* CONFIG_MMU */
>   
>   #if USE_SPLIT_PTE_PTLOCKS
> @@ -2252,11 +2212,6 @@ static inline void pgtable_pte_page_dtor(struct page *page)
>   	((unlikely(pmd_none(*(pmd))) && __pte_alloc_kernel(pmd))? \
>   		NULL: pte_offset_kernel(pmd, address))
>   
> -#define pte_alloc_kernel_track(pmd, address, mask)			\
> -	((unlikely(pmd_none(*(pmd))) &&					\
> -	  (__pte_alloc_kernel(pmd) || ({*(mask)|=PGTBL_PMD_MODIFIED;0;})))?\
> -		NULL: pte_offset_kernel(pmd, address))
> -
>   #if USE_SPLIT_PMD_PTLOCKS
>   
>   static struct page *pmd_to_page(pmd_t *pmd)
> diff --git a/include/linux/pgalloc-track.h b/include/linux/pgalloc-track.h
> new file mode 100644
> index 000000000000..1dcc865029a2
> --- /dev/null
> +++ b/include/linux/pgalloc-track.h
> @@ -0,0 +1,51 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _LINUX_PGALLLC_TRACK_H
> +#define _LINUX_PGALLLC_TRACK_H
> +
> +#if defined(CONFIG_MMU)
> +static inline p4d_t *p4d_alloc_track(struct mm_struct *mm, pgd_t *pgd,
> +				     unsigned long address,
> +				     pgtbl_mod_mask *mod_mask)
> +{
> +	if (unlikely(pgd_none(*pgd))) {
> +		if (__p4d_alloc(mm, pgd, address))
> +			return NULL;
> +		*mod_mask |= PGTBL_PGD_MODIFIED;
> +	}
> +
> +	return p4d_offset(pgd, address);
> +}
> +
> +static inline pud_t *pud_alloc_track(struct mm_struct *mm, p4d_t *p4d,
> +				     unsigned long address,
> +				     pgtbl_mod_mask *mod_mask)
> +{
> +	if (unlikely(p4d_none(*p4d))) {
> +		if (__pud_alloc(mm, p4d, address))
> +			return NULL;
> +		*mod_mask |= PGTBL_P4D_MODIFIED;
> +	}
> +
> +	return pud_offset(p4d, address);
> +}
> +
> +static inline pmd_t *pmd_alloc_track(struct mm_struct *mm, pud_t *pud,
> +				     unsigned long address,
> +				     pgtbl_mod_mask *mod_mask)
> +{
> +	if (unlikely(pud_none(*pud))) {
> +		if (__pmd_alloc(mm, pud, address))
> +			return NULL;
> +		*mod_mask |= PGTBL_PUD_MODIFIED;
> +	}
> +
> +	return pmd_offset(pud, address);
> +}
> +#endif /* CONFIG_MMU */
> +
> +#define pte_alloc_kernel_track(pmd, address, mask)			\
> +	((unlikely(pmd_none(*(pmd))) &&					\
> +	  (__pte_alloc_kernel(pmd) || ({*(mask)|=PGTBL_PMD_MODIFIED;0;})))?\
> +		NULL: pte_offset_kernel(pmd, address))
> +
> +#endif /* _LINUX_PGALLLC_TRACK_H */
> diff --git a/lib/ioremap.c b/lib/ioremap.c
> index ad485f08173b..608fcccd21c8 100644
> --- a/lib/ioremap.c
> +++ b/lib/ioremap.c
> @@ -11,6 +11,7 @@
>   #include <linux/sched.h>
>   #include <linux/io.h>
>   #include <linux/export.h>
> +#include <linux/pgalloc-track.h>
>   #include <asm/cacheflush.h>
>   #include <asm/pgtable.h>
>   
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 3091c2ca60df..edc43f003165 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -35,6 +35,7 @@
>   #include <linux/bitops.h>
>   #include <linux/rbtree_augmented.h>
>   #include <linux/overflow.h>
> +#include <linux/pgalloc-track.h>
>   
>   #include <linux/uaccess.h>
>   #include <asm/tlbflush.h>
>