linux-kernel - Re: [Part3 PATCH v2 0/4] Support hot-remove local pagetable pages.

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Date:	Mon, 17 Jun 2013 10:07:29 +0800
From:	Tang Chen <tangchen@...fujitsu.com>
To:	Jianguo Wu <wujianguo@...wei.com>
CC:	tglx@...utronix.de, mingo@...e.hu, hpa@...or.com,
	akpm@...ux-foundation.org, tj@...nel.org, trenn@...e.de,
	yinghai@...nel.org, jiang.liu@...wei.com, wency@...fujitsu.com,
	laijs@...fujitsu.com, isimatu.yasuaki@...fujitsu.com,
	mgorman@...e.de, minchan@...nel.org, mina86@...a86.com,
	gong.chen@...ux.intel.com, vasilis.liaskovitis@...fitbricks.com,
	lwoodman@...hat.com, riel@...hat.com, jweiner@...hat.com,
	prarit@...hat.com, x86@...nel.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [Part3 PATCH v2 0/4] Support hot-remove local pagetable pages.

On 06/17/2013 09:58 AM, Jianguo Wu wrote:
> Hi Tang,
>
> On 2013/6/13 21:03, Tang Chen wrote:
>
>> The following patch-set from Yinghai allocates pagetables to local nodes.
>> v1: https://lkml.org/lkml/2013/3/7/642
>> v2: https://lkml.org/lkml/2013/3/10/47
>> v3: https://lkml.org/lkml/2013/4/4/639
>> v4: https://lkml.org/lkml/2013/4/11/829
>>
>> Since pagetable pages are used by the kernel, they cannot be offlined.
>> As a result, they cannot be hot-remove.
>>
>> This patch fix this problem with the following solution:
>>
>>       1.   Introduce a new bootmem type LOCAL_NODE_DATAL, and register local
>>            pagetable pages as LOCAL_NODE_DATAL by setting page->lru.next to
>>            LOCAL_NODE_DATAL, just like we register SECTION_INFO pages.
>>
>>       2.   Skip LOCAL_NODE_DATAL pages in offline/online procedures. When the
>>            whole memory block they reside in is offlined, the kernel can
>>            still access the pagetables.
>>            (This changes the semantics of offline/online a little bit.)
>>
>>       3.   Do not free LOCAL_NODE_DATAL pages to buddy system because they
>>            were skipped when in offline/online procedures. The memory block
>>            they reside in could have been offlined.
>>
>
> s/LOCAL_NODE_DATAL/LOCAL_NODE_DATA

Oh...thank you. Will send a new version soon. :)

>
>> Anyway, this problem should be fixed. Any better idea is welcome.
>>
>> Change log:
>> v1 ->  v2:
>>          patch2: As suggested by Wu Jianguo, define a macro to check if a page
>>                  cantains local node data.
>>          patch4: As suggested by Wu Jianguo, prevent freeing LOCAL_NODE_DATA
>>                  pages in free_pagetable() instead of in put_page_bootmem().
>>
>> Tang Chen (4):
>>    bootmem, mem-hotplug: Register local pagetable pages with
>>      LOCAL_NODE_DATA when freeing bootmem.
>>    mem-hotplug: Skip LOCAL_NODE_DATA pages in memory offline procedure.
>>    mem-hotplug: Skip LOCAL_NODE_DATA pages in memory online procedure.
>>    mem-hotplug: Do not free LOCAL_NODE_DATA pages to buddy system in
>>      hot-remove procedure.
>>
>>   arch/x86/mm/init_64.c          |   10 +++++++-
>>   include/linux/memblock.h       |   22 +++++++++++++++++
>>   include/linux/memory_hotplug.h |   20 +++++++++++++--
>>   mm/memblock.c                  |   52 ++++++++++++++++++++++++++++++++++++++++
>>   mm/memory_hotplug.c            |   31 +++++++++++++++++++++++
>>   mm/page_alloc.c                |   15 ++++++++++-
>>   mm/page_isolation.c            |    5 ++++
>>   7 files changed, 149 insertions(+), 6 deletions(-)
>>
>> --
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>>
>> .
>>
>
>
>
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