linux-kernel - Re: [PATCH 10/14] mm, vmstat: skip reporting offline pages in pagetypeinfo

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Message-ID: <15260936-353e-2513-e751-2117f142bfa8@suse.cz>
Date:   Fri, 19 May 2017 10:17:24 +0200
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Michal Hocko <mhocko@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-mm@...ck.org, Mel Gorman <mgorman@...e.de>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Jerome Glisse <jglisse@...hat.com>,
        Reza Arbab <arbab@...ux.vnet.ibm.com>,
        Yasuaki Ishimatsu <yasu.isimatu@...il.com>,
        qiuxishi@...wei.com, Kani Toshimitsu <toshi.kani@....com>,
        slaoub@...il.com, Joonsoo Kim <js1304@...il.com>,
        Andi Kleen <ak@...ux.intel.com>,
        David Rientjes <rientjes@...gle.com>,
        Daniel Kiper <daniel.kiper@...cle.com>,
        Igor Mammedov <imammedo@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Michal Hocko <mhocko@...e.com>
Subject: Re: [PATCH 10/14] mm, vmstat: skip reporting offline pages in
 pagetypeinfo

On 05/15/2017 10:58 AM, Michal Hocko wrote:
> From: Michal Hocko <mhocko@...e.com>
> 
> pagetypeinfo_showblockcount_print skips over invalid pfns but it would
> report pages which are offline because those have a valid pfn. Their
> migrate type is misleading at best. Now that we have pfn_to_online_page()
> we can use it instead of pfn_valid() and fix this.
> 
> Noticed-by: Joonsoo Kim <js1304@...il.com>
> Signed-off-by: Michal Hocko <mhocko@...e.com>

(with the followup fix)

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

> ---
>  mm/vmstat.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 571d3ec05566..c432e581f9a9 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -1223,11 +1223,9 @@ static void pagetypeinfo_showblockcount_print(struct seq_file *m,
>  	for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
>  		struct page *page;
>  
> -		if (!pfn_valid(pfn))
> +		if (!pfn_to_online_page(pfn))
>  			continue;
>  
> -		page = pfn_to_page(pfn);
> -
>  		/* Watch for unexpected holes punched in the memmap */
>  		if (!memmap_valid_within(pfn, page, zone))
>  			continue;
>