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

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Date:	Thu, 13 Jun 2013 21:03:52 +0800
From:	Tang Chen <tangchen@...fujitsu.com>
To:	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
Cc:	x86@...nel.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: [Part3 PATCH v2 0/4] Support hot-remove local pagetable pages.

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.

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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