Re: [PATCH 1/3] mm: split out a new pagewalk.h header from mm.h

[Mike Rapoport <rppt@linux.ibm.com>]

On Wed, Aug 28, 2019 at 04:19:53PM +0200, Christoph Hellwig wrote:
> Add a new header for the two handful of users of the walk_page_range /
> walk_page_vma interface instead of polluting all users of mm.h with it.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
> Reviewed-by: Steven Price <steven.price@arm.com>
> ---
>  arch/openrisc/kernel/dma.c              |  1 +
>  arch/powerpc/mm/book3s64/subpage_prot.c |  2 +-
>  arch/s390/mm/gmap.c                     |  2 +-
>  fs/proc/task_mmu.c                      |  2 +-
>  include/linux/mm.h                      | 46 ---------------------
>  include/linux/pagewalk.h                | 54 +++++++++++++++++++++++++
>  mm/hmm.c                                |  2 +-
>  mm/madvise.c                            |  1 +
>  mm/memcontrol.c                         |  2 +-
>  mm/mempolicy.c                          |  2 +-
>  mm/migrate.c                            |  1 +
>  mm/mincore.c                            |  2 +-
>  mm/mprotect.c                           |  2 +-
>  mm/pagewalk.c                           |  2 +-
>  14 files changed, 66 insertions(+), 55 deletions(-)
>  create mode 100644 include/linux/pagewalk.h
> 
> diff --git a/arch/openrisc/kernel/dma.c b/arch/openrisc/kernel/dma.c
> index b41a79fcdbd9..c7812e6effa2 100644
> --- a/arch/openrisc/kernel/dma.c
> +++ b/arch/openrisc/kernel/dma.c
> @@ -16,6 +16,7 @@
>   */
>  
>  #include <linux/dma-noncoherent.h>
> +#include <linux/pagewalk.h>
>  
>  #include <asm/cpuinfo.h>
>  #include <asm/spr_defs.h>
> diff --git a/arch/powerpc/mm/book3s64/subpage_prot.c b/arch/powerpc/mm/book3s64/subpage_prot.c
> index 9ba07e55c489..236f0a861ecc 100644
> --- a/arch/powerpc/mm/book3s64/subpage_prot.c
> +++ b/arch/powerpc/mm/book3s64/subpage_prot.c
> @@ -7,7 +7,7 @@
>  #include <linux/kernel.h>
>  #include <linux/gfp.h>
>  #include <linux/types.h>
> -#include <linux/mm.h>
> +#include <linux/pagewalk.h>
>  #include <linux/hugetlb.h>
>  #include <linux/syscalls.h>
>  
> diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
> index 39c3a6e3d262..cf80feae970d 100644
> --- a/arch/s390/mm/gmap.c
> +++ b/arch/s390/mm/gmap.c
> @@ -9,7 +9,7 @@
>   */
>  
>  #include <linux/kernel.h>
> -#include <linux/mm.h>
> +#include <linux/pagewalk.h>
>  #include <linux/swap.h>
>  #include <linux/smp.h>
>  #include <linux/spinlock.h>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 731642e0f5a0..8857da830b86 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -1,5 +1,5 @@
>  // SPDX-License-Identifier: GPL-2.0
> -#include <linux/mm.h>
> +#include <linux/pagewalk.h>
>  #include <linux/vmacache.h>
>  #include <linux/hugetlb.h>
>  #include <linux/huge_mm.h>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 0334ca97c584..7cf955feb823 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1430,54 +1430,8 @@ void zap_page_range(struct vm_area_struct *vma, unsigned long address,
>  void unmap_vmas(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
>  		unsigned long start, unsigned long end);
>  
> -/**
> - * mm_walk - callbacks for walk_page_range
> - * @pud_entry: if set, called for each non-empty PUD (2nd-level) entry
> - *	       this handler should only handle pud_trans_huge() puds.
> - *	       the pmd_entry or pte_entry callbacks will be used for
> - *	       regular PUDs.
> - * @pmd_entry: if set, called for each non-empty PMD (3rd-level) entry
> - *	       this handler is required to be able to handle
> - *	       pmd_trans_huge() pmds.  They may simply choose to
> - *	       split_huge_page() instead of handling it explicitly.
> - * @pte_entry: if set, called for each non-empty PTE (4th-level) entry
> - * @pte_hole: if set, called for each hole at all levels
> - * @hugetlb_entry: if set, called for each hugetlb entry
> - * @test_walk: caller specific callback function to determine whether
> - *             we walk over the current vma or not. Returning 0
> - *             value means "do page table walk over the current vma,"
> - *             and a negative one means "abort current page table walk
> - *             right now." 1 means "skip the current vma."
> - * @mm:        mm_struct representing the target process of page table walk
> - * @vma:       vma currently walked (NULL if walking outside vmas)
> - * @private:   private data for callbacks' usage
> - *
> - * (see the comment on walk_page_range() for more details)
> - */
> -struct mm_walk {
> -	int (*pud_entry)(pud_t *pud, unsigned long addr,
> -			 unsigned long next, struct mm_walk *walk);
> -	int (*pmd_entry)(pmd_t *pmd, unsigned long addr,
> -			 unsigned long next, struct mm_walk *walk);
> -	int (*pte_entry)(pte_t *pte, unsigned long addr,
> -			 unsigned long next, struct mm_walk *walk);
> -	int (*pte_hole)(unsigned long addr, unsigned long next,
> -			struct mm_walk *walk);
> -	int (*hugetlb_entry)(pte_t *pte, unsigned long hmask,
> -			     unsigned long addr, unsigned long next,
> -			     struct mm_walk *walk);
> -	int (*test_walk)(unsigned long addr, unsigned long next,
> -			struct mm_walk *walk);
> -	struct mm_struct *mm;
> -	struct vm_area_struct *vma;
> -	void *private;
> -};
> -
>  struct mmu_notifier_range;
>  
> -int walk_page_range(unsigned long addr, unsigned long end,
> -		struct mm_walk *walk);
> -int walk_page_vma(struct vm_area_struct *vma, struct mm_walk *walk);
>  void free_pgd_range(struct mmu_gather *tlb, unsigned long addr,
>  		unsigned long end, unsigned long floor, unsigned long ceiling);
>  int copy_page_range(struct mm_struct *dst, struct mm_struct *src,
> diff --git a/include/linux/pagewalk.h b/include/linux/pagewalk.h
> new file mode 100644
> index 000000000000..df278a94086d
> --- /dev/null
> +++ b/include/linux/pagewalk.h
> @@ -0,0 +1,54 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _LINUX_PAGEWALK_H
> +#define _LINUX_PAGEWALK_H
> +
> +#include <linux/mm.h>
> +
> +/**
> + * mm_walk - callbacks for walk_page_range
> + * @pud_entry: if set, called for each non-empty PUD (2nd-level) entry

Sorry for jumping late, can we remove the level numbers here and below?
PUD can be non-existent, 2nd or 3rd (from top) and PTE can be from 2nd to
5th...

I'd completely drop the numbers and mark PTE as "lowest level".

> + *	       this handler should only handle pud_trans_huge() puds.
> + *	       the pmd_entry or pte_entry callbacks will be used for
> + *	       regular PUDs.
> + * @pmd_entry: if set, called for each non-empty PMD (3rd-level) entry
> + *	       this handler is required to be able to handle
> + *	       pmd_trans_huge() pmds.  They may simply choose to
> + *	       split_huge_page() instead of handling it explicitly.
> + * @pte_entry: if set, called for each non-empty PTE (4th-level) entry
> + * @pte_hole: if set, called for each hole at all levels
> + * @hugetlb_entry: if set, called for each hugetlb entry
> + * @test_walk: caller specific callback function to determine whether
> + *             we walk over the current vma or not. Returning 0
> + *             value means "do page table walk over the current vma,"
> + *             and a negative one means "abort current page table walk
> + *             right now." 1 means "skip the current vma."
> + * @mm:        mm_struct representing the target process of page table walk
> + * @vma:       vma currently walked (NULL if walking outside vmas)
> + * @private:   private data for callbacks' usage
> + *
> + * (see the comment on walk_page_range() for more details)
> + */
> +struct mm_walk {
> +	int (*pud_entry)(pud_t *pud, unsigned long addr,
> +			 unsigned long next, struct mm_walk *walk);
> +	int (*pmd_entry)(pmd_t *pmd, unsigned long addr,
> +			 unsigned long next, struct mm_walk *walk);
> +	int (*pte_entry)(pte_t *pte, unsigned long addr,
> +			 unsigned long next, struct mm_walk *walk);
> +	int (*pte_hole)(unsigned long addr, unsigned long next,
> +			struct mm_walk *walk);
> +	int (*hugetlb_entry)(pte_t *pte, unsigned long hmask,
> +			     unsigned long addr, unsigned long next,
> +			     struct mm_walk *walk);
> +	int (*test_walk)(unsigned long addr, unsigned long next,
> +			struct mm_walk *walk);
> +	struct mm_struct *mm;
> +	struct vm_area_struct *vma;
> +	void *private;
> +};
> +
> +int walk_page_range(unsigned long addr, unsigned long end,
> +		struct mm_walk *walk);
> +int walk_page_vma(struct vm_area_struct *vma, struct mm_walk *walk);
> +
> +#endif /* _LINUX_PAGEWALK_H */
> diff --git a/mm/hmm.c b/mm/hmm.c
> index 4882b83aeccb..26916ff6c8df 100644
> --- a/mm/hmm.c
> +++ b/mm/hmm.c
> @@ -8,7 +8,7 @@
>   * Refer to include/linux/hmm.h for information about heterogeneous memory
>   * management or HMM for short.
>   */
> -#include <linux/mm.h>
> +#include <linux/pagewalk.h>
>  #include <linux/hmm.h>
>  #include <linux/init.h>
>  #include <linux/rmap.h>
> diff --git a/mm/madvise.c b/mm/madvise.c
> index 968df3aa069f..80a78bb16782 100644
> --- a/mm/madvise.c
> +++ b/mm/madvise.c
> @@ -20,6 +20,7 @@
>  #include <linux/file.h>
>  #include <linux/blkdev.h>
>  #include <linux/backing-dev.h>
> +#include <linux/pagewalk.h>
>  #include <linux/swap.h>
>  #include <linux/swapops.h>
>  #include <linux/shmem_fs.h>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 6f5c0c517c49..4c3af5d71ab1 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -25,7 +25,7 @@
>  #include <linux/page_counter.h>
>  #include <linux/memcontrol.h>
>  #include <linux/cgroup.h>
> -#include <linux/mm.h>
> +#include <linux/pagewalk.h>
>  #include <linux/sched/mm.h>
>  #include <linux/shmem_fs.h>
>  #include <linux/hugetlb.h>
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index 65e0874fce17..3a96def1e796 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -68,7 +68,7 @@
>  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>  
>  #include <linux/mempolicy.h>
> -#include <linux/mm.h>
> +#include <linux/pagewalk.h>
>  #include <linux/highmem.h>
>  #include <linux/hugetlb.h>
>  #include <linux/kernel.h>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 962cb62c621f..c9c73a35aca7 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -38,6 +38,7 @@
>  #include <linux/hugetlb.h>
>  #include <linux/hugetlb_cgroup.h>
>  #include <linux/gfp.h>
> +#include <linux/pagewalk.h>
>  #include <linux/pfn_t.h>
>  #include <linux/memremap.h>
>  #include <linux/userfaultfd_k.h>
> diff --git a/mm/mincore.c b/mm/mincore.c
> index 4fe91d497436..3b051b6ab3fe 100644
> --- a/mm/mincore.c
> +++ b/mm/mincore.c
> @@ -10,7 +10,7 @@
>   */
>  #include <linux/pagemap.h>
>  #include <linux/gfp.h>
> -#include <linux/mm.h>
> +#include <linux/pagewalk.h>
>  #include <linux/mman.h>
>  #include <linux/syscalls.h>
>  #include <linux/swap.h>
> diff --git a/mm/mprotect.c b/mm/mprotect.c
> index bf38dfbbb4b4..cc73318dbc25 100644
> --- a/mm/mprotect.c
> +++ b/mm/mprotect.c
> @@ -9,7 +9,7 @@
>   *  (C) Copyright 2002 Red Hat Inc, All Rights Reserved
>   */
>  
> -#include <linux/mm.h>
> +#include <linux/pagewalk.h>
>  #include <linux/hugetlb.h>
>  #include <linux/shm.h>
>  #include <linux/mman.h>
> diff --git a/mm/pagewalk.c b/mm/pagewalk.c
> index c3084ff2569d..8a92a961a2ee 100644
> --- a/mm/pagewalk.c
> +++ b/mm/pagewalk.c
> @@ -1,5 +1,5 @@
>  // SPDX-License-Identifier: GPL-2.0
> -#include <linux/mm.h>
> +#include <linux/pagewalk.h>
>  #include <linux/highmem.h>
>  #include <linux/sched.h>
>  #include <linux/hugetlb.h>
> -- 
> 2.20.1
> 
> 

-- 
Sincerely yours,
Mike.