linux-kernel - Re: [PATCH v2 4/5] mm/page_owner: add zone range overlapping check

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Message-ID: <56FE2F0A.3000803@suse.cz>
Date:	Fri, 1 Apr 2016 10:19:22 +0200
From:	Vlastimil Babka <vbabka@...e.cz>
To:	js1304@...il.com, Andrew Morton <akpm@...ux-foundation.org>
Cc:	Rik van Riel <riel@...hat.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Mel Gorman <mgorman@...e.de>,
	Laura Abbott <lauraa@...eaurora.org>,
	Minchan Kim <minchan@...nel.org>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Michal Nazarewicz <mina86@...a86.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH v2 4/5] mm/page_owner: add zone range overlapping check

On 1.4.2016 4:06, js1304@...il.com wrote:
> From: Joonsoo Kim <iamjoonsoo.kim@....com>
> 
> There is a system that node's pfn are overlapped like as following.
> 
> -----pfn-------->
> N0 N1 N2 N0 N1 N2
> 
> Therefore, we need to care this overlapping when iterating pfn range.
> 
> There are one place in page_owner.c that iterates pfn range and
> it doesn't consider this overlapping. Add it.
> 
> Without this patch, above system could over count early allocated
> page number before page_owner is activated.
> 
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>

Acked-by: Vlastimil Babka <vbabka@...e.cz>

> ---
>  mm/page_owner.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/mm/page_owner.c b/mm/page_owner.c
> index ac3d8d1..438768c 100644
> --- a/mm/page_owner.c
> +++ b/mm/page_owner.c
> @@ -301,6 +301,9 @@ static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
>  
>  			page = pfn_to_page(pfn);
>  
> +			if (page_zone(page) != zone)
> +				continue;
> +
>  			/*
>  			 * We are safe to check buddy flag and order, because
>  			 * this is init stage and only single thread runs.
>