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Subject: Re: [PATCH v2 4/5] mm/page_owner: add zone range overlapping check
To: js1304@gmail.com, Andrew Morton <akpm@linux-foundation.org>
References: <1459476406-28418-1-git-send-email-iamjoonsoo.kim@lge.com>
 <1459476406-28418-5-git-send-email-iamjoonsoo.kim@lge.com>
Cc: Rik van Riel <riel@redhat.com>, Johannes Weiner <hannes@cmpxchg.org>,
        Mel Gorman <mgorman@suse.de>, Laura Abbott <lauraa@codeaurora.org>,
        Minchan Kim <minchan@kernel.org>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Michal Nazarewicz <mina86@mina86.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Joonsoo Kim <iamjoonsoo.kim@lge.com>
From: Vlastimil Babka <vbabka@suse.cz>
Message-ID: <56FE2F0A.3000803@suse.cz>
Date: Fri, 1 Apr 2016 10:19:22 +0200
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On 1.4.2016 4:06, js1304@gmail.com wrote:
> From: Joonsoo Kim <iamjoonsoo.kim@lge.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@lge.com>

Acked-by: Vlastimil Babka <vbabka@suse.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.
>