linux-kernel - Re: [PATCH v10 09/69] mm: add VMA iterator

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Message-ID: <20192b57-30de-1426-6694-238e018104eb@redhat.com>
Date:   Tue, 21 Jun 2022 23:10:09 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Liam Howlett <liam.howlett@...cle.com>,
        "maple-tree@...ts.infradead.org" <maple-tree@...ts.infradead.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "damon @ lists . linux . dev" <damon@...ts.linux.dev>,
        SeongJae Park <sj@...nel.org>
Subject: Re: [PATCH v10 09/69] mm: add VMA iterator

On 21.06.22 22:46, Liam Howlett wrote:
> From: "Matthew Wilcox (Oracle)" <willy@...radead.org>
> 
> This thin layer of abstraction over the maple tree state is for iterating
> over VMAs.  You can go forwards, go backwards or ask where the iterator
> is.  Rename the existing vma_next() to __vma_next() -- it will be removed
> by the end of this series.
> 
> Link: https://lkml.kernel.org/r/20220504010716.661115-11-Liam.Howlett@oracle.com
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
> Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
> Acked-by: Vlastimil Babka <vbabka@...e.cz>
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: David Howells <dhowells@...hat.com>
> Cc: SeongJae Park <sj@...nel.org>
> Cc: Will Deacon <will@...nel.org>
> Cc: Davidlohr Bueso <dave@...olabs.net>
> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
> ---
>  include/linux/mm.h       | 31 +++++++++++++++++++++++++++++++
>  include/linux/mm_types.h | 21 +++++++++++++++++++++
>  mm/mmap.c                | 10 +++++-----
>  3 files changed, 57 insertions(+), 5 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 810b3dd929e4..f22c6f71a18c 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -658,6 +658,37 @@ static inline bool vma_is_accessible(struct vm_area_struct *vma)
>  	return vma->vm_flags & VM_ACCESS_FLAGS;
>  }
>  
> +static inline
> +struct vm_area_struct *vma_find(struct vma_iterator *vmi, unsigned long max)
> +{
> +	return mas_find(&vmi->mas, max);
> +}
> +
> +static inline struct vm_area_struct *vma_next(struct vma_iterator *vmi)
> +{
> +	/*
> +	 * Uses vma_find() to get the first VMA when the iterator starts.
> +	 * Calling mas_next() could skip the first entry.
> +	 */
> +	return vma_find(vmi, ULONG_MAX);
> +}
> +
> +static inline struct vm_area_struct *vma_prev(struct vma_iterator *vmi)
> +{
> +	return mas_prev(&vmi->mas, 0);
> +}
> +
> +static inline unsigned long vma_iter_addr(struct vma_iterator *vmi)
> +{
> +	return vmi->mas.index;
> +}
> +
> +#define for_each_vma(vmi, vma)		while ((vma = vma_next(&(vmi))) != NULL)
> +
> +/* The MM code likes to work with exclusive end addresses */
> +#define for_each_vma_range(vmi, vma, end)				\
> +	while ((vma = vma_find(&(vmi), (end) - 1)) != NULL)
> +
>  #ifdef CONFIG_SHMEM
>  /*
>   * The vma_is_shmem is not inline because it is used only by slow
> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> index 254c30def2b2..1485a24796be 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -696,6 +696,27 @@ static inline cpumask_t *mm_cpumask(struct mm_struct *mm)
>  	return (struct cpumask *)&mm->cpu_bitmap;
>  }
>  
> +struct vma_iterator {
> +	struct ma_state mas;
> +};
> +
> +#define VMA_ITERATOR(name, mm, addr) 					\
> +	struct vma_iterator name = {					\
> +		.mas = {						\
> +			.tree = &mm->mm_mt,				\
> +			.index = addr,					\
> +			.node = MAS_START,				\
> +		},							\
> +	}
> +

No __* and () macro magic?

I'd have expected at least

tree = &(__mm)->mm_mt,
.index = (__addr),

;)


Reviewed-by: David Hildenbrand <david@...hat.com>

-- 
Thanks,

David / dhildenb