Re: [PATCHv2 1/4] mm/zbud: zbud_alloc() minor param change

[Seth Jennings]

On Wed, May 07, 2014 at 05:51:33PM -0400, Dan Streetman wrote:
> Change zbud to store gfp_t flags passed at pool creation to use for
> each alloc; this allows the api to be closer to the existing zsmalloc
> interface, and the only current zbud user (zswap) uses the same gfp
> flags for all allocs.  Update zswap to use changed interface.
> 

Acked-by: Seth Jennings <sjennings@xxxxxxxxxxxxxx>

> Signed-off-by: Dan Streetman <ddstreet@xxxxxxxx>
> Cc: Seth Jennings <sjennings@xxxxxxxxxxxxxx>
> Cc: Weijie Yang <weijie.yang@xxxxxxxxxxx>
> ---
> 
> Changes since v1 https://lkml.org/lkml/2014/4/19/98
>  -context changes only; zbud_alloc parameter type changed since
>   last patch
> 
>  include/linux/zbud.h |  2 +-
>  mm/zbud.c            | 27 +++++++++++++++------------
>  mm/zswap.c           |  6 +++---
>  3 files changed, 19 insertions(+), 16 deletions(-)
> 
> diff --git a/include/linux/zbud.h b/include/linux/zbud.h
> index 13af0d4..0b2534e 100644
> --- a/include/linux/zbud.h
> +++ b/include/linux/zbud.h
> @@ -11,7 +11,7 @@ struct zbud_ops {
>  
>  struct zbud_pool *zbud_create_pool(gfp_t gfp, struct zbud_ops *ops);
>  void zbud_destroy_pool(struct zbud_pool *pool);
> -int zbud_alloc(struct zbud_pool *pool, unsigned int size, gfp_t gfp,
> +int zbud_alloc(struct zbud_pool *pool, unsigned int size,
>  	unsigned long *handle);
>  void zbud_free(struct zbud_pool *pool, unsigned long handle);
>  int zbud_reclaim_page(struct zbud_pool *pool, unsigned int retries);
> diff --git a/mm/zbud.c b/mm/zbud.c
> index 01df13a..847c01c 100644
> --- a/mm/zbud.c
> +++ b/mm/zbud.c
> @@ -94,6 +94,7 @@ struct zbud_pool {
>  	struct list_head lru;
>  	u64 pages_nr;
>  	struct zbud_ops *ops;
> +	gfp_t gfp;
>  };
>  
>  /*
> @@ -193,9 +194,12 @@ static int num_free_chunks(struct zbud_header *zhdr)
>  *****************/
>  /**
>   * zbud_create_pool() - create a new zbud pool
> - * @gfp:	gfp flags when allocating the zbud pool structure
> + * @gfp:	gfp flags when growing the pool
>   * @ops:	user-defined operations for the zbud pool
>   *
> + * gfp should not set __GFP_HIGHMEM as highmem pages cannot be used
> + * as zbud pool pages.
> + *
>   * Return: pointer to the new zbud pool or NULL if the metadata allocation
>   * failed.
>   */
> @@ -204,7 +208,9 @@ struct zbud_pool *zbud_create_pool(gfp_t gfp, struct zbud_ops *ops)
>  	struct zbud_pool *pool;
>  	int i;
>  
> -	pool = kmalloc(sizeof(struct zbud_pool), gfp);
> +	if (gfp & __GFP_HIGHMEM)
> +		return NULL;
> +	pool = kmalloc(sizeof(struct zbud_pool), GFP_KERNEL);
>  	if (!pool)
>  		return NULL;
>  	spin_lock_init(&pool->lock);
> @@ -214,6 +220,7 @@ struct zbud_pool *zbud_create_pool(gfp_t gfp, struct zbud_ops *ops)
>  	INIT_LIST_HEAD(&pool->lru);
>  	pool->pages_nr = 0;
>  	pool->ops = ops;
> +	pool->gfp = gfp;
>  	return pool;
>  }
>  
> @@ -232,7 +239,6 @@ void zbud_destroy_pool(struct zbud_pool *pool)
>   * zbud_alloc() - allocates a region of a given size
>   * @pool:	zbud pool from which to allocate
>   * @size:	size in bytes of the desired allocation
> - * @gfp:	gfp flags used if the pool needs to grow
>   * @handle:	handle of the new allocation
>   *
>   * This function will attempt to find a free region in the pool large enough to
> @@ -240,14 +246,11 @@ void zbud_destroy_pool(struct zbud_pool *pool)
>   * performed first. If no suitable free region is found, then a new page is
>   * allocated and added to the pool to satisfy the request.
>   *
> - * gfp should not set __GFP_HIGHMEM as highmem pages cannot be used
> - * as zbud pool pages.
> - *
> - * Return: 0 if success and handle is set, otherwise -EINVAL if the size or
> - * gfp arguments are invalid or -ENOMEM if the pool was unable to allocate
> - * a new page.
> + * Return: 0 if success and @handle is set, -ENOSPC if the @size is too large,
> + * -EINVAL if the @size is 0, or -ENOMEM if the pool was unable to
> + * allocate a new page.
>   */
> -int zbud_alloc(struct zbud_pool *pool, unsigned int size, gfp_t gfp,
> +int zbud_alloc(struct zbud_pool *pool, unsigned int size,
>  			unsigned long *handle)
>  {
>  	int chunks, i, freechunks;
> @@ -255,7 +258,7 @@ int zbud_alloc(struct zbud_pool *pool, unsigned int size, gfp_t gfp,
>  	enum buddy bud;
>  	struct page *page;
>  
> -	if (!size || (gfp & __GFP_HIGHMEM))
> +	if (!size)
>  		return -EINVAL;
>  	if (size > PAGE_SIZE - ZHDR_SIZE_ALIGNED - CHUNK_SIZE)
>  		return -ENOSPC;
> @@ -279,7 +282,7 @@ int zbud_alloc(struct zbud_pool *pool, unsigned int size, gfp_t gfp,
>  
>  	/* Couldn't find unbuddied zbud page, create new one */
>  	spin_unlock(&pool->lock);
> -	page = alloc_page(gfp);
> +	page = alloc_page(pool->gfp);
>  	if (!page)
>  		return -ENOMEM;
>  	spin_lock(&pool->lock);
> diff --git a/mm/zswap.c b/mm/zswap.c
> index aeaef0f..1cc6770 100644
> --- a/mm/zswap.c
> +++ b/mm/zswap.c
> @@ -679,8 +679,7 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
>  
>  	/* store */
>  	len = dlen + sizeof(struct zswap_header);
> -	ret = zbud_alloc(zswap_pool, len, __GFP_NORETRY | __GFP_NOWARN,
> -		&handle);
> +	ret = zbud_alloc(zswap_pool, len, &handle);
>  	if (ret == -ENOSPC) {
>  		zswap_reject_compress_poor++;
>  		goto freepage;
> @@ -900,7 +899,8 @@ static int __init init_zswap(void)
>  
>  	pr_info("loading zswap\n");
>  
> -	zswap_pool = zbud_create_pool(GFP_KERNEL, &zswap_zbud_ops);
> +	zswap_pool = zbud_create_pool(__GFP_NORETRY | __GFP_NOWARN,
> +			&zswap_zbud_ops);
>  	if (!zswap_pool) {
>  		pr_err("zbud pool creation failed\n");
>  		goto error;
> -- 
> 1.8.3.1
> 
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