linux-kernel - Re: [PATCH v3 06/16] zsmalloc: squeeze inuse into page->mapping

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Date:	Mon, 18 Apr 2016 00:08:04 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:	Minchan Kim <minchan@...nel.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	jlayton@...chiereds.net, bfields@...ldses.org,
	Vlastimil Babka <vbabka@...e.cz>,
	Joonsoo Kim <iamjoonsoo.kim@....com>, koct9i@...il.com,
	aquini@...hat.com, virtualization@...ts.linux-foundation.org,
	Mel Gorman <mgorman@...e.de>, Hugh Dickins <hughd@...gle.com>,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	Rik van Riel <riel@...hat.com>, rknize@...orola.com,
	Gioh Kim <gi-oh.kim@...fitbricks.com>,
	Sangseok Lee <sangseok.lee@....com>,
	Chan Gyun Jeong <chan.jeong@....com>,
	Al Viro <viro@...IV.linux.org.uk>,
	YiPing Xu <xuyiping@...ilicon.com>
Subject: Re: [PATCH v3 06/16] zsmalloc: squeeze inuse into page->mapping

Hello,

On (03/30/16 16:12), Minchan Kim wrote:
[..]
> +static int get_zspage_inuse(struct page *first_page)
> +{
> +	struct zs_meta *m;
> +
> +	VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
> +
> +	m = (struct zs_meta *)&first_page->mapping;
..
> +static void set_zspage_inuse(struct page *first_page, int val)
> +{
> +	struct zs_meta *m;
> +
> +	VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
> +
> +	m = (struct zs_meta *)&first_page->mapping;
..
> +static void mod_zspage_inuse(struct page *first_page, int val)
> +{
> +	struct zs_meta *m;
> +
> +	VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
> +
> +	m = (struct zs_meta *)&first_page->mapping;
..
>  static void get_zspage_mapping(struct page *first_page,
>  				unsigned int *class_idx,
>  				enum fullness_group *fullness)
>  {
> -	unsigned long m;
> +	struct zs_meta *m;
> +
>  	VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
> +	m = (struct zs_meta *)&first_page->mapping;
..
>  static void set_zspage_mapping(struct page *first_page,
>  				unsigned int class_idx,
>  				enum fullness_group fullness)
>  {
> +	struct zs_meta *m;
> +
>  	VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
>  
> +	m = (struct zs_meta *)&first_page->mapping;
> +	m->fullness = fullness;
> +	m->class = class_idx;
>  }


a nitpick: this

	struct zs_meta *m;
	VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
	m = (struct zs_meta *)&first_page->mapping;


seems to be common in several places, may be it makes sense to
factor it out and turn into a macro or a static inline helper?

other than that, looks good to me

Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>

	-ss