From mboxrd@z Thu Jan  1 00:00:00 1970
From: Wen Congyang <wency@cn.fujitsu.com>
Subject: Re: [PATCH] mm: make zone_pcp_reset independ on MEMORY_HOTREMOVE
Date: Tue, 23 Oct 2012 18:14:28 +0800
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To: Michal Hocko <mhocko@suse.cz>
Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mmc@vger.kernel.org, David Rientjes <rientjes@google.com>, Jiang Liu <liuj97@gmail.com>, Len Brown <len.brown@intel.com>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Paul Mackerras <paulus@samba.org>, Christoph Lameter <cl@linux.com>, Minchan Kim <minchan.kim@gmail.com>, KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>, Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>, Dave Hansen <dave@linux.vnet.ibm.com>, Mel Gorman <mel@csn.ul.ie>

At 10/23/2012 05:37 PM, Michal Hocko Wrote:
> 340175b7 (mm/hotplug: free zone->pageset when a zone becomes empty)
> introduced zone_pcp_reset and hided it inside CONFIG_MEMORY_HOTREMOVE.
> The function is since 506e5fb7 (memory-hotplug: allocate zone's pcp
> before onlining pages) called also called from online_pages which

This patch is still in -mm tree, and I have received a report from
Liu Yuanhan.

> is called outside CONFIG_MEMORY_HOTREMOVE which causes a linkage error.
> 
> The function, although not used outside of MEMORY_{HOTPLUT,HOTREMOVE},
> seems like universal enough so let's keep it at its current location
> and only remove the HOTREMOVE guard.
> 
> Signed-off-by: Michal Hocko <mhocko@suse.cz>
> Cc: David Rientjes <rientjes@google.com>
> Cc: Jiang Liu <liuj97@gmail.com>
> Cc: Len Brown <len.brown@intel.com>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Christoph Lameter <cl@linux.com>
> Cc: Minchan Kim <minchan.kim@gmail.com>
> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
> Cc: Dave Hansen <dave@linux.vnet.ibm.com>
> Cc: Mel Gorman <mel@csn.ul.ie>
> ---
>  mm/page_alloc.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index e29912e..30e359c 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5981,7 +5981,6 @@ void __meminit zone_pcp_update(struct zone *zone)
>  }
>  #endif
>  
> -#ifdef CONFIG_MEMORY_HOTREMOVE
>  void zone_pcp_reset(struct zone *zone)
>  {
>  	unsigned long flags;
> @@ -6001,6 +6000,7 @@ void zone_pcp_reset(struct zone *zone)
>  	local_irq_restore(flags);
>  }
>  
> +#ifdef CONFIG_MEMORY_HOTREMOVE
>  /*
>   * All pages in the range must be isolated before calling this.
>   */

This patch looks find to me.

Reviewed-by: Wen Congyang <wency@cn.fujitsu.com>