linux-kernel - Re: [RFC] mm/zsmalloc: remove redundant SetPagePrivate2 in create_page

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Message-ID: <20170215071344.GA23887@bbox>
Date:   Wed, 15 Feb 2017 16:13:44 +0900
From:   Minchan Kim <minchan@...nel.org>
To:     Yisheng Xie <xieyisheng1@...wei.com>
CC:     <akpm@...ux-foundation.org>, <ngupta@...are.org>,
        <sergey.senozhatsky.work@...il.com>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, <guohanjun@...wei.com>
Subject: Re: [RFC] mm/zsmalloc: remove redundant SetPagePrivate2 in
 create_page_chain

On Tue, Feb 14, 2017 at 08:48:29PM +0800, Yisheng Xie wrote:
> We had used page->lru to link the component pages (except the first
> page) of a zspage, and used INIT_LIST_HEAD(&page->lru) to init it.
> Therefore, to get the last page's next page, which is NULL, we had to
> use page flag PG_Private_2 to identify it.
> 
> But now, we use page->freelist to link all of the pages in zspage and
> init the page->freelist as NULL for last page, so no need to use
> PG_Private_2 anymore.
> 
> This patch is to remove redundant SetPagePrivate2 in create_page_chain
> and ClearPagePrivate2 in reset_page(). Maybe can save few cycles for
> migration of zsmalloc page :)
> 
> Signed-off-by: Yisheng Xie <xieyisheng1@...wei.com>
Acked-by: Minchan Kim <minchan@...nel.org>

Thanks, Yisheng!