linux-kernel - Re: [PATCH v2 3/4] mm, madvise: move madvise_set_anon

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Message-ID: <c009828a-821d-4f88-9dd0-b8abde64714e@lucifer.local>
Date: Tue, 24 Jun 2025 16:36:20 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Vlastimil Babka <vbabka@...e.cz>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
        "Liam R. Howlett" <Liam.Howlett@...cle.com>,
        David Hildenbrand <david@...hat.com>, Jann Horn <jannh@...gle.com>,
        Mike Rapoport <rppt@...nel.org>,
        Suren Baghdasaryan <surenb@...gle.com>, Michal Hocko <mhocko@...e.com>,
        Colin Cross <ccross@...gle.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/4] mm, madvise: move madvise_set_anon_name() down
 the file

On Tue, Jun 24, 2025 at 03:03:47PM +0200, Vlastimil Babka wrote:
> Preparatory change so that we can use madvise_lock()/unlock() in the
> function without forward declarations or more thorough shuffling.
>
> Signed-off-by: Vlastimil Babka <vbabka@...e.cz>

Fine, but I think this is small enough of a move to be safely combined with 4/4
as David says.

Either way:

Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>

> ---
>  mm/madvise.c | 64 ++++++++++++++++++++++++++++++------------------------------
>  1 file changed, 32 insertions(+), 32 deletions(-)
>
> diff --git a/mm/madvise.c b/mm/madvise.c
> index 7e8819b5e9a0f183213ffe19d7e52bd5fda5f49d..cae064479cdf908707c45b941bd03d43d095eab6 100644
> --- a/mm/madvise.c
> +++ b/mm/madvise.c
> @@ -133,38 +133,6 @@ static int replace_anon_vma_name(struct vm_area_struct *vma,
>
>  	return 0;
>  }
> -
> -static int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
> -		unsigned long len_in, struct anon_vma_name *anon_name)
> -{
> -	unsigned long end;
> -	unsigned long len;
> -	struct madvise_behavior madv_behavior = {
> -		.mm = mm,
> -		.behavior = __MADV_SET_ANON_VMA_NAME,
> -		.lock_mode = MADVISE_MMAP_WRITE_LOCK,
> -		.anon_name = anon_name,
> -	};
> -
> -	if (start & ~PAGE_MASK)
> -		return -EINVAL;
> -	len = (len_in + ~PAGE_MASK) & PAGE_MASK;
> -
> -	/* Check to see whether len was rounded up from small -ve to zero */
> -	if (len_in && !len)
> -		return -EINVAL;
> -
> -	end = start + len;
> -	if (end < start)
> -		return -EINVAL;
> -
> -	if (end == start)
> -		return 0;
> -
> -	madv_behavior.range.start = start;
> -	madv_behavior.range.end = end;
> -	return madvise_walk_vmas(&madv_behavior);
> -}
>  #else /* CONFIG_ANON_VMA_NAME */
>  static int replace_anon_vma_name(struct vm_area_struct *vma,
>  				 struct anon_vma_name *anon_name)
> @@ -2109,6 +2077,38 @@ static inline bool is_valid_name_char(char ch)
>  		!strchr(ANON_VMA_NAME_INVALID_CHARS, ch);
>  }
>
> +static int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
> +		unsigned long len_in, struct anon_vma_name *anon_name)
> +{
> +	unsigned long end;
> +	unsigned long len;
> +	struct madvise_behavior madv_behavior = {
> +		.mm = mm,
> +		.behavior = __MADV_SET_ANON_VMA_NAME,
> +		.lock_mode = MADVISE_MMAP_WRITE_LOCK,
> +		.anon_name = anon_name,
> +	};
> +
> +	if (start & ~PAGE_MASK)
> +		return -EINVAL;
> +	len = (len_in + ~PAGE_MASK) & PAGE_MASK;
> +
> +	/* Check to see whether len was rounded up from small -ve to zero */
> +	if (len_in && !len)
> +		return -EINVAL;
> +
> +	end = start + len;
> +	if (end < start)
> +		return -EINVAL;
> +
> +	if (end == start)
> +		return 0;
> +
> +	madv_behavior.range.start = start;
> +	madv_behavior.range.end = end;
> +	return madvise_walk_vmas(&madv_behavior);
> +}
> +
>  int set_anon_vma_name(unsigned long addr, unsigned long size,
>  		      const char __user *uname)
>  {
>
> --
> 2.50.0
>