linux-kernel - Re: [PATCH 2/5] mm/vmalloc: Extend __alloc_vmap

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Date:   Wed, 8 Jun 2022 11:46:33 +0800
From:   Baoquan He <bhe@...hat.com>
To:     "Uladzislau Rezki (Sony)" <urezki@...il.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        LKML <linux-kernel@...r.kernel.org>,
        Christoph Hellwig <hch@...radead.org>,
        Matthew Wilcox <willy@...radead.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...y.com>
Subject: Re: [PATCH 2/5] mm/vmalloc: Extend __alloc_vmap_area() with extra
 arguments

On 06/07/22 at 11:34am, Uladzislau Rezki (Sony) wrote:
> It implies that __alloc_vmap_area() allocates only from the
> global vmap space, therefore a list-head and rb-tree, which
> represent a free vmap space, are not passed as parameters to
> this function and are accessed directly from this function.
> 
> Extend the __alloc_vmap_area() and other dependent functions
> to have a possibility to allocate from different trees making
> an interface common and not specific.
> 
> There is no functional change as a result of this patch.

LGTM,

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

> 
> Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
> ---
>  mm/vmalloc.c | 30 ++++++++++++++++--------------
>  1 file changed, 16 insertions(+), 14 deletions(-)
> 
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 0102d6d5fcdf..745e89eb6ca1 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -1234,15 +1234,15 @@ is_within_this_va(struct vmap_area *va, unsigned long size,
>   * overhead.
>   */
>  static __always_inline struct vmap_area *
> -find_vmap_lowest_match(unsigned long size, unsigned long align,
> -	unsigned long vstart, bool adjust_search_size)
> +find_vmap_lowest_match(struct rb_root *root, unsigned long size,
> +	unsigned long align, unsigned long vstart, bool adjust_search_size)
>  {
>  	struct vmap_area *va;
>  	struct rb_node *node;
>  	unsigned long length;
>  
>  	/* Start from the root. */
> -	node = free_vmap_area_root.rb_node;
> +	node = root->rb_node;
>  
>  	/* Adjust the search size for alignment overhead. */
>  	length = adjust_search_size ? size + align - 1 : size;
> @@ -1370,9 +1370,9 @@ classify_va_fit_type(struct vmap_area *va,
>  }
>  
>  static __always_inline int
> -adjust_va_to_fit_type(struct vmap_area *va,
> -	unsigned long nva_start_addr, unsigned long size,
> -	enum fit_type type)
> +adjust_va_to_fit_type(struct rb_root *root, struct list_head *head,
> +	struct vmap_area *va, unsigned long nva_start_addr,
> +	unsigned long size, enum fit_type type)
>  {
>  	struct vmap_area *lva = NULL;
>  
> @@ -1384,7 +1384,7 @@ adjust_va_to_fit_type(struct vmap_area *va,
>  		 * V      NVA      V
>  		 * |---------------|
>  		 */
> -		unlink_va_augment(va, &free_vmap_area_root);
> +		unlink_va_augment(va, root);
>  		kmem_cache_free(vmap_area_cachep, va);
>  	} else if (type == LE_FIT_TYPE) {
>  		/*
> @@ -1462,8 +1462,7 @@ adjust_va_to_fit_type(struct vmap_area *va,
>  		augment_tree_propagate_from(va);
>  
>  		if (lva)	/* type == NE_FIT_TYPE */
> -			insert_vmap_area_augment(lva, &va->rb_node,
> -				&free_vmap_area_root, &free_vmap_area_list);
> +			insert_vmap_area_augment(lva, &va->rb_node, root, head);
>  	}
>  
>  	return 0;
> @@ -1474,7 +1473,8 @@ adjust_va_to_fit_type(struct vmap_area *va,
>   * Otherwise a vend is returned that indicates failure.
>   */
>  static __always_inline unsigned long
> -__alloc_vmap_area(unsigned long size, unsigned long align,
> +__alloc_vmap_area(struct rb_root *root, struct list_head *head,
> +	unsigned long size, unsigned long align,
>  	unsigned long vstart, unsigned long vend)
>  {
>  	bool adjust_search_size = true;
> @@ -1495,7 +1495,7 @@ __alloc_vmap_area(unsigned long size, unsigned long align,
>  	if (align <= PAGE_SIZE || (align > PAGE_SIZE && (vend - vstart) == size))
>  		adjust_search_size = false;
>  
> -	va = find_vmap_lowest_match(size, align, vstart, adjust_search_size);
> +	va = find_vmap_lowest_match(root, size, align, vstart, adjust_search_size);
>  	if (unlikely(!va))
>  		return vend;
>  
> @@ -1514,7 +1514,7 @@ __alloc_vmap_area(unsigned long size, unsigned long align,
>  		return vend;
>  
>  	/* Update the free vmap_area. */
> -	ret = adjust_va_to_fit_type(va, nva_start_addr, size, type);
> +	ret = adjust_va_to_fit_type(root, head, va, nva_start_addr, size, type);
>  	if (ret)
>  		return vend;
>  
> @@ -1605,7 +1605,8 @@ static struct vmap_area *alloc_vmap_area(unsigned long size,
>  
>  retry:
>  	preload_this_cpu_lock(&free_vmap_area_lock, gfp_mask, node);
> -	addr = __alloc_vmap_area(size, align, vstart, vend);
> +	addr = __alloc_vmap_area(&free_vmap_area_root, &free_vmap_area_list,
> +		size, align, vstart, vend);
>  	spin_unlock(&free_vmap_area_lock);
>  
>  	/*
> @@ -3886,7 +3887,8 @@ struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
>  			/* It is a BUG(), but trigger recovery instead. */
>  			goto recovery;
>  
> -		ret = adjust_va_to_fit_type(va, start, size, type);
> +		ret = adjust_va_to_fit_type(&free_vmap_area_root,
> +				&free_vmap_area_list, va, start, size, type);
>  		if (unlikely(ret))
>  			goto recovery;
>  
> -- 
> 2.30.2
> 
>