linux-kernel - Re: [PATCH v2] mm/mmap: introduce vma_set

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Date: Wed, 24 Jan 2024 10:47:56 -0500
From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
To: Yajun Deng <yajun.deng@...ux.dev>
Cc: akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] mm/mmap: introduce vma_set_range()

* Yajun Deng <yajun.deng@...ux.dev> [240123 22:57]:
> There is a lot of code needs to set the range of vma in mmap.c,
> introduce vma_set_range() to simplify the code.
> 
> Signed-off-by: Yajun Deng <yajun.deng@...ux.dev>

Thank you for making the suggested changes, I have one small comment but
you don't need to re-spin the patch for it.  This looks good.

Reviewed-by: Liam R. Howlett <Liam.Howlett@...cle.com>

> ---
> v2: use vma_set_range and put it to mm/internal.h.
> v1: https://lore.kernel.org/all/20240111021526.3461825-1-yajun.deng@linux.dev/
> ---
>  mm/internal.h |  9 +++++++++
>  mm/mmap.c     | 29 +++++++----------------------
>  2 files changed, 16 insertions(+), 22 deletions(-)
> 
> diff --git a/mm/internal.h b/mm/internal.h
> index f309a010d50f..1e29c5821a1d 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -1114,6 +1114,15 @@ static inline bool gup_must_unshare(struct vm_area_struct *vma,
>  extern bool mirrored_kernelcore;
>  extern bool memblock_has_mirror(void);
>  
> +static __always_inline void vma_set_range(struct vm_area_struct *vma,
> +					  unsigned long start, unsigned long end,
> +					  pgoff_t pgoff)

Nit: This isn't part of the style guide, but if you just indent with two
tabs for arguments then it is easier to expand the list without more
lines.  It also allows changing the function prototype without
re-indenting all the other lines, so future changes can be smaller.  I
think you would save a line here without affecting readability.

> +{
> +	vma->vm_start = start;
> +	vma->vm_end = end;
> +	vma->vm_pgoff = pgoff;
> +}
> +
>  static inline bool vma_soft_dirty_enabled(struct vm_area_struct *vma)
>  {
>  	/*
> diff --git a/mm/mmap.c b/mm/mmap.c
> index cf2f058bb3ae..7a9d2895a1bd 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -663,9 +663,7 @@ int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma,
>  
>  	vma_prepare(&vp);
>  	vma_adjust_trans_huge(vma, start, end, 0);
> -	vma->vm_start = start;
> -	vma->vm_end = end;
> -	vma->vm_pgoff = pgoff;
> +	vma_set_range(vma, start, end, pgoff);
>  	vma_iter_store(vmi, vma);
>  
>  	vma_complete(&vp, vmi, vma->vm_mm);
> @@ -708,9 +706,7 @@ int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma,
>  	vma_adjust_trans_huge(vma, start, end, 0);
>  
>  	vma_iter_clear(vmi);
> -	vma->vm_start = start;
> -	vma->vm_end = end;
> -	vma->vm_pgoff = pgoff;
> +	vma_set_range(vma, start, end, pgoff);
>  	vma_complete(&vp, vmi, vma->vm_mm);
>  	return 0;
>  }
> @@ -1015,10 +1011,7 @@ static struct vm_area_struct
>  
>  	vma_prepare(&vp);
>  	vma_adjust_trans_huge(vma, vma_start, vma_end, adj_start);
> -
> -	vma->vm_start = vma_start;
> -	vma->vm_end = vma_end;
> -	vma->vm_pgoff = vma_pgoff;
> +	vma_set_range(vma, vma_start, vma_end, vma_pgoff);
>  
>  	if (vma_expanded)
>  		vma_iter_store(vmi, vma);
> @@ -2809,11 +2802,9 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
>  	}
>  
>  	vma_iter_config(&vmi, addr, end);
> -	vma->vm_start = addr;
> -	vma->vm_end = end;
> +	vma_set_range(vma, addr, end, pgoff);
>  	vm_flags_init(vma, vm_flags);
>  	vma->vm_page_prot = vm_get_page_prot(vm_flags);
> -	vma->vm_pgoff = pgoff;
>  
>  	if (file) {
>  		vma->vm_file = get_file(file);
> @@ -3163,9 +3154,7 @@ static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma,
>  		goto unacct_fail;
>  
>  	vma_set_anonymous(vma);
> -	vma->vm_start = addr;
> -	vma->vm_end = addr + len;
> -	vma->vm_pgoff = addr >> PAGE_SHIFT;
> +	vma_set_range(vma, addr, addr + len, addr >> PAGE_SHIFT);
>  	vm_flags_init(vma, flags);
>  	vma->vm_page_prot = vm_get_page_prot(flags);
>  	vma_start_write(vma);
> @@ -3402,9 +3391,7 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
>  		new_vma = vm_area_dup(vma);
>  		if (!new_vma)
>  			goto out;
> -		new_vma->vm_start = addr;
> -		new_vma->vm_end = addr + len;
> -		new_vma->vm_pgoff = pgoff;
> +		vma_set_range(new_vma, addr, addr + len, pgoff);
>  		if (vma_dup_policy(vma, new_vma))
>  			goto out_free_vma;
>  		if (anon_vma_clone(new_vma, vma))
> @@ -3572,9 +3559,7 @@ static struct vm_area_struct *__install_special_mapping(
>  	if (unlikely(vma == NULL))
>  		return ERR_PTR(-ENOMEM);
>  
> -	vma->vm_start = addr;
> -	vma->vm_end = addr + len;
> -
> +	vma_set_range(vma, addr, addr + len, 0);
>  	vm_flags_init(vma, (vm_flags | mm->def_flags |
>  		      VM_DONTEXPAND | VM_SOFTDIRTY) & ~VM_LOCKED_MASK);
>  	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
> -- 
> 2.25.1
>