linux-kernel - Re: [PATCH 2/5] mm/debug_pagealloc: don't allocate page

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Message-ID: <20160810094442.GA674@swordfish>
Date:	Wed, 10 Aug 2016 18:44:42 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:	js1304@...il.com
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Vlastimil Babka <vbabka@...e.cz>,
	Minchan Kim <minchan@...nel.org>,
	Michal Hocko <mhocko@...nel.org>,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH 2/5] mm/debug_pagealloc: don't allocate page_ext if we
 don't use guard page

On (08/10/16 15:16), js1304@...il.com wrote:
> From: Joonsoo Kim <iamjoonsoo.kim@....com>
> 
> What debug_pagealloc does is just mapping/unmapping page table.
> Basically, it doesn't need additional memory space to memorize something.
> But, with guard page feature, it requires additional memory to distinguish
> if the page is for guard or not. Guard page is only used when
> debug_guardpage_minorder is non-zero so this patch removes additional
> memory allocation (page_ext) if debug_guardpage_minorder is zero.
> 
> It saves memory if we just use debug_pagealloc and not guard page.
> 
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>

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

	-ss