linux-kernel - Re: [PATCH v2 2/2] mem-hotplug: Reset node present pages when hot-adding a new pgdat.

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Message-ID: <54600665.5090503@jp.fujitsu.com>
Date:	Mon, 10 Nov 2014 09:27:17 +0900
From:	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
To:	Tang Chen <tangchen@...fujitsu.com>, <akpm@...ux-foundation.org>,
	<santosh.shilimkar@...com>, <grygorii.strashko@...com>,
	<yinghai@...nel.org>, <isimatu.yasuaki@...fujitsu.com>,
	<fabf@...net.be>, <nzimmer@....com>, <wangnan0@...wei.com>,
	<vdavydov@...allels.com>, <toshi.kani@...com>,
	<phacht@...ux.vnet.ibm.com>, <tj@...nel.org>,
	<kirill.shutemov@...ux.intel.com>, <riel@...hat.com>,
	<luto@...capital.net>, <hpa@...ux.intel.com>,
	<aarcange@...hat.com>, <qiuxishi@...wei.com>, <mgorman@...e.de>,
	<rientjes@...gle.com>, <hannes@...xchg.org>
CC:	<linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
	<miaox@...fujitsu.com>
Subject: Re: [PATCH v2 2/2] mem-hotplug: Reset node present pages when hot-adding
 a new pgdat.

(2014/11/07 18:44), Tang Chen wrote:
> When onlining memory on node2, node2 zoneinfo and node3 meminfo corrupted:
> 
> # for ((i = 2048; i < 2064; i++)); do echo online_movable > /sys/devices/system/node/node2/memory$i/state; done
> # cat /sys/devices/system/node/node2/meminfo
> Node 2 MemTotal:       33554432 kB
> Node 2 MemFree:        33549092 kB
> Node 2 MemUsed:            5340 kB
> ......
> # cat /sys/devices/system/node/node3/meminfo
> Node 3 MemTotal:              0 kB
> Node 3 MemFree:               248 kB      /* corrupted, should be 0 */
> Node 3 MemUsed:               0 kB
> ......
> 
> # cat /proc/zoneinfo
> ......
> Node 2, zone   Movable
> ......
>          spanned  8388608
>          present  16777216               /* corrupted, should be 8388608 */
>          managed  8388608
> 
> 
> When memory is hot-added, all the memory is in offline state. So
> clear all zone->present_pages because they will be updated in
> online_pages() and offline_pages().
> 
> Signed-off-by: Tang Chen <tangchen@...fujitsu.com>
> ---

Looks good to me.

Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>

Thanks,
Yasuaki Ishimatsu

>   mm/memory_hotplug.c | 15 +++++++++++++++
>   1 file changed, 15 insertions(+)
> 
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 8aba12b..26eac61 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1067,6 +1067,14 @@ out:
>   }
>   #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
>   
> +static void reset_node_present_pages(pg_data_t *pgdat)
> +{
> +        struct zone *z;
> +
> +        for (z = pgdat->node_zones; z < pgdat->node_zones + MAX_NR_ZONES; z++)
> +                z->present_pages = 0;
> +}
> +
>   /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
>   static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
>   {
> @@ -1105,6 +1113,13 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
>   	 */
>   	reset_node_managed_pages(pgdat);
>   
> +	/*
> +	 * When memory is hot-added, all the memory is in offline state. So
> +	 * clear all zones' present_pages because they will be updated in
> +	 * online_pages() and offline_pages().
> +	 */
> +	reset_node_present_pages(pgdat);
> +
>   	return pgdat;
>   }
>   
> 


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