linux-kernel - Re: [PATCH v2 1/9] mm: vmalloc: Add va

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Message-ID: <ZPgTR19GX9EI8J0d@MiWiFi-R3L-srv>
Date:   Wed, 6 Sep 2023 13:51:03 +0800
From:   Baoquan He <bhe@...hat.com>
To:     "Uladzislau Rezki (Sony)" <urezki@...il.com>
Cc:     linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Lorenzo Stoakes <lstoakes@...il.com>,
        Christoph Hellwig <hch@...radead.org>,
        Matthew Wilcox <willy@...radead.org>,
        "Liam R . Howlett" <Liam.Howlett@...cle.com>,
        Dave Chinner <david@...morbit.com>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...y.com>,
        Christoph Hellwig <hch@....de>
Subject: Re: [PATCH v2 1/9] mm: vmalloc: Add va_alloc() helper

On 08/29/23 at 10:11am, Uladzislau Rezki (Sony) wrote:
> Currently __alloc_vmap_area() function contains an open codded
> logic that finds and adjusts a VA based on allocation request.
> 
> Introduce a va_alloc() helper that adjusts found VA only. It
> will be used later at least in two places.
> 
> There is no a functional change as a result of this patch.
> 
> Reviewed-by: Christoph Hellwig <hch@....de>
> Reviewed-by: Lorenzo Stoakes <lstoakes@...il.com>
> Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
> ---
>  mm/vmalloc.c | 41 ++++++++++++++++++++++++++++-------------
>  1 file changed, 28 insertions(+), 13 deletions(-)
> 
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 93cf99aba335..00afc1ee4756 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -1481,6 +1481,32 @@ adjust_va_to_fit_type(struct rb_root *root, struct list_head *head,
>  	return 0;
>  }
>  
> +static unsigned long
> +va_alloc(struct vmap_area *va,
> +		struct rb_root *root, struct list_head *head,
> +		unsigned long size, unsigned long align,
> +		unsigned long vstart, unsigned long vend)
> +{
> +	unsigned long nva_start_addr;
> +	int ret;
> +
> +	if (va->va_start > vstart)
> +		nva_start_addr = ALIGN(va->va_start, align);
> +	else
> +		nva_start_addr = ALIGN(vstart, align);
> +
> +	/* Check the "vend" restriction. */
> +	if (nva_start_addr + size > vend)
> +		return vend;
> +
> +	/* Update the free vmap_area. */
> +	ret = adjust_va_to_fit_type(root, head, va, nva_start_addr, size);
> +	if (WARN_ON_ONCE(ret))
> +		return vend;
> +
> +	return nva_start_addr;
> +}
> +
>  /*
>   * Returns a start address of the newly allocated area, if success.
>   * Otherwise a vend is returned that indicates failure.
> @@ -1493,7 +1519,6 @@ __alloc_vmap_area(struct rb_root *root, struct list_head *head,
>  	bool adjust_search_size = true;
>  	unsigned long nva_start_addr;
>  	struct vmap_area *va;
> -	int ret;
>  
>  	/*
>  	 * Do not adjust when:
> @@ -1511,18 +1536,8 @@ __alloc_vmap_area(struct rb_root *root, struct list_head *head,
>  	if (unlikely(!va))
>  		return vend;
>  
> -	if (va->va_start > vstart)
> -		nva_start_addr = ALIGN(va->va_start, align);
> -	else
> -		nva_start_addr = ALIGN(vstart, align);
> -
> -	/* Check the "vend" restriction. */
> -	if (nva_start_addr + size > vend)
> -		return vend;
> -
> -	/* Update the free vmap_area. */
> -	ret = adjust_va_to_fit_type(root, head, va, nva_start_addr, size);
> -	if (WARN_ON_ONCE(ret))
> +	nva_start_addr = va_alloc(va, root, head, size, align, vstart, vend);
> +	if (nva_start_addr == vend)
>  		return vend;
>  
>  #if DEBUG_AUGMENT_LOWEST_MATCH_CHECK
> -- 
> 2.30.2

Reviewed-by: Baoquan He <bhe@...hat.com>