linux-kernel - Re: [PATCH v2 1/2] mem-hotplug: Reset node managed pages when hot-adding a new pgdat.

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Date:	Tue, 11 Nov 2014 13:54:09 +0900
From:	Greg KH <gregkh@...uxfoundation.org>
To:	Tang Chen <tangchen@...fujitsu.com>
Cc:	akpm@...ux-foundation.org, santosh.shilimkar@...com,
	grygorii.strashko@...com, yinghai@...nel.org,
	isimatu.yasuaki@...fujitsu.co, 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, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, miaox@...fujitsu.com,
	stable@...r.kernel.org,
	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
Subject: Re: [PATCH v2 1/2] mem-hotplug: Reset node managed pages when
 hot-adding a new pgdat.

On Tue, Nov 11, 2014 at 09:27:06AM +0800, Tang Chen wrote:
> In free_area_init_core(), zone->managed_pages is set to an approximate
> value for lowmem, and will be adjusted when the bootmem allocator frees
> pages into the buddy system. But free_area_init_core() is also called
> by hotadd_new_pgdat() when hot-adding memory. As a result, zone->managed_pages
> of the newly added node's pgdat is set to an approximate value in the
> very beginning. Even if the memory on that node has node been onlined,
> /sys/device/system/node/nodeXXX/meminfo has wrong value.
> 
> hot-add node2 (memory not onlined)
> cat /sys/device/system/node/node2/meminfo
> Node 2 MemTotal:       33554432 kB
> Node 2 MemFree:               0 kB
> Node 2 MemUsed:        33554432 kB
> Node 2 Active:                0 kB
> 
> This patch fixes this problem by reset node managed pages to 0 after hot-adding
> a new node.
> 
> 1. Move reset_managed_pages_done from reset_node_managed_pages() to reset_all_zones_managed_pages()
> 2. Make reset_node_managed_pages() non-static
> 3. Call reset_node_managed_pages() in hotadd_new_pgdat() after pgdat is initialized
> 
> Signed-off-by: Tang Chen <tangchen@...fujitsu.com>
> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
> ---
>  include/linux/bootmem.h | 1 +
>  mm/bootmem.c            | 9 +++++----
>  mm/memory_hotplug.c     | 9 +++++++++
>  mm/nobootmem.c          | 8 +++++---
>  4 files changed, 20 insertions(+), 7 deletions(-)

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read Documentation/stable_kernel_rules.txt
for how to do this properly.

</formletter>
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