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

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Date:	Tue, 19 Apr 2016 16:40:59 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
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>,
	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

On Mon, Apr 18, 2016 at 12:08:04AM +0900, Sergey Senozhatsky wrote:
> 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

Yeb.

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

Thanks for the review!