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

From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
To: Minchan Kim <minchan@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	jlayton@poochiereds.net, bfields@fieldses.org,
	Vlastimil Babka <vbabka@suse.cz>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	koct9i@gmail.com, aquini@redhat.com,
	virtualization@lists.linux-foundation.org,
	Mel Gorman <mgorman@suse.de>, Hugh Dickins <hughd@google.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Rik van Riel <riel@redhat.com>,
	rknize@motorola.com, Gioh Kim <gi-oh.kim@profitbricks.com>,
	Sangseok Lee <sangseok.lee@lge.com>,
	Chan Gyun Jeong <chan.jeong@lge.com>,
	Al Viro <viro@ZenIV.linux.org.uk>,
	YiPing Xu <xuyiping@hisilicon.com>
Subject: Re: [PATCH v3 06/16] zsmalloc: squeeze inuse into page->mapping
Date: Mon, 18 Apr 2016 00:08:04 +0900	[thread overview]
Message-ID: <20160417150804.GA575@swordfish> (raw)
In-Reply-To: <1459321935-3655-7-git-send-email-minchan@kernel.org>

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@gmail.com>

	-ss