Subject: Re: [RFC v9 PATCH 00/21] memory-hotplug: hot-remove physical memory

From: Yasuaki Ishimatsu <[email-masked]>
Date: Tue, 2 Oct 2012 09:02:51 +0900

Hi Chen,

2012/10/02 8:45, Ni zhan Chen wrote:
> On 10/01/2012 12:44 PM, Yasuaki Ishimatsu wrote:
>> Hi Chen,
>>
>> 2012/09/29 17:19, Ni zhan Chen wrote:
>>> On 09/05/2012 05:25 PM, [email-masked] wrote:
>>>> From: Wen Congyang <[email-masked]>
>>>>
>>>> This patch series aims to support physical memory hot-remove.
>>>>
>>>> The patches can free/remove the following things:
>>>>
>>>>    - acpi_memory_info                          : [RFC PATCH 4/19]
>>>>    - /sys/firmware/memmap/X/{end, start, type} : [RFC PATCH 8/19]
>>>>    - iomem_resource                            : [RFC PATCH 9/19]
>>>>    - mem_section and related sysfs files       : [RFC PATCH 10-11, 13-16/19]
>>>>    - page table of removed memory              : [RFC PATCH 12/19]
>>>>    - node and related sysfs files              : [RFC PATCH 18-19/19]
>>>>
>>>> If you find lack of function for physical memory hot-remove, please let me
>>>> know.
>>>>
>>>> How to test this patchset?
>>>> 1. apply this patchset and build the kernel. MEMORY_HOTPLUG, MEMORY_HOTREMOVE,
>>>>     ACPI_HOTPLUG_MEMORY must be selected.
>>>> 2. load the module acpi_memhotplug
>>>
>>> Hi Yasuaki,
>>>
>>> where is the acpi_memhotplug module?
>>
>> If you build acpi_memhotplug as module, it is created under
>> /lib/modules/<kernel-version>/driver/acpi/ directory. It depends
>> on config ACPI_HOTPLUG_MEMORY. The confing is [*], it becomes built-in
>> function. So you don't need to care about it.
>> Thanks,
>> Yasuaki Ishimatsu
>
> Hi Yasuaki,
>
> I build the kernel, MEMORY_HOTPLUG, MEMORY_HOTREMOVE, ACPI_HOTPLUG_MEMORY are seleted as [*], but I can't find PNP0C80:XX under the directory /sys/bus/acpi/devices/.
>
> [root@localhost ~]# ls /sys/bus/acpi/devices/
> device:00  device:07  device:0e  device:15  device:1c  device:23 device:2a   LNXCPU:00  LNXCPU:07    PNP0501:00  PNP0C02:00 PNP0C0F:02 PNP0C14:01
> device:01  device:08  device:0f  device:16  device:1d  device:24 device:2b   LNXCPU:01  LNXPWRBN:00  PNP0800:00  PNP0C02:01 PNP0C0F:03 PNP0C31:00
> device:02  device:09  device:10  device:17  device:1e  device:25 device:2c   LNXCPU:02  LNXSYSTM:00  PNP0A08:00  PNP0C02:02 PNP0C0F:04
> device:03  device:0a  device:11  device:18  device:1f  device:26 device:2d   LNXCPU:03  PNP0000:00   PNP0B00:00  PNP0C04:00 PNP0C0F:05
> device:04  device:0b  device:12  device:19  device:20  device:27 device:2e   LNXCPU:04  PNP0100:00   PNP0C01:00  PNP0C0C:00 PNP0C0F:06
> device:05  device:0c  device:13  device:1a  device:21  device:28 device:2f   LNXCPU:05  PNP0103:00   PNP0C01:01  PNP0C0F:00 PNP0C0F:07
> device:06  device:0d  device:14  device:1b  device:22  device:29 INT3F0D:00  LNXCPU:06  PNP0200:00   PNP0C01:02  PNP0C0F:01 PNP0C14:00
>
> then what I miss ? thanks.

It depend on hardware. It seems that your system does not support
memory hotplug. If you use KVM, you can try memory hotplug on KVM
guest by applying Vasilis' patch-set.

http://lists.gnu.org/archive/html/qemu-devel/2012-07/msg01389.html

Thanks,
Yasuaki Ishimatsu

>
>>
>>>
>>>> 3. hotplug the memory device(it depends on your hardware)
>>>>     You will see the memory device under the directory /sys/bus/acpi/devices/.
>>>>     Its name is PNP0C80:XX.
>>>> 4. online/offline pages provided by this memory device
>>>>     You can write online/offline to /sys/devices/system/memory/memoryX/state to
>>>>     online/offline pages provided by this memory device
>>>> 5. hotremove the memory device
>>>>     You can hotremove the memory device by the hardware, or writing 1 to
>>>>     /sys/bus/acpi/devices/PNP0C80:XX/eject.
>>>>
>>>> Note: if the memory provided by the memory device is used by the kernel, it
>>>> can't be offlined. It is not a bug.
>>>>
>>>> Known problems:
>>>> 1. memory can't be offlined when CONFIG_MEMCG is selected.
>>>>     For example: there is a memory device on node 1. The address range
>>>>     is [1G, 1.5G). You will find 4 new directories memory8, memory9, memory10,
>>>>     and memory11 under the directory /sys/devices/system/memory/.
>>>>     If CONFIG_MEMCG is selected, we will allocate memory to store page cgroup
>>>>     when we online pages. When we online memory8, the memory stored page cgroup
>>>>     is not provided by this memory device. But when we online memory9, the memory
>>>>     stored page cgroup may be provided by memory8. So we can't offline memory8
>>>>     now. We should offline the memory in the reversed order.
>>>>     When the memory device is hotremoved, we will auto offline memory provided
>>>>     by this memory device. But we don't know which memory is onlined first, so
>>>>     offlining memory may fail. In such case, you should offline the memory by
>>>>     hand before hotremoving the memory device.
>>>> 2. hotremoving memory device may cause kernel panicked
>>>>     This bug will be fixed by Liu Jiang's patch:
>>>>     https://lkml.org/lkml/2012/7/3/1
>>>>
>>>> change log of v9:
>>>>   [RFC PATCH v9 8/21]
>>>>     * add a lock to protect the list map_entries
>>>>     * add an indicator to firmware_map_entry to remember whether the memory
>>>>       is allocated from bootmem
>>>>   [RFC PATCH v9 10/21]
>>>>     * change the macro to inline function
>>>>   [RFC PATCH v9 19/21]
>>>>     * don't offline the node if the cpu on the node is onlined
>>>>   [RFC PATCH v9 21/21]
>>>>     * create new patch: auto offline page_cgroup when onlining memory block
>>>>       failed
>>>>
>>>> change log of v8:
>>>>   [RFC PATCH v8 17/20]
>>>>     * Fix problems when one node's range include the other nodes
>>>>   [RFC PATCH v8 18/20]
>>>>     * fix building error when CONFIG_MEMORY_HOTPLUG_SPARSE or CONFIG_HUGETLBFS
>>>>       is not defined.
>>>>   [RFC PATCH v8 19/20]
>>>>     * don't offline node when some memory sections are not removed
>>>>   [RFC PATCH v8 20/20]
>>>>     * create new patch: clear hwpoisoned flag when onlining pages
>>>>
>>>> change log of v7:
>>>>   [RFC PATCH v7 4/19]
>>>>     * do not continue if acpi_memory_device_remove_memory() fails.
>>>>   [RFC PATCH v7 15/19]
>>>>     * handle usemap in register_page_bootmem_info_section() too.
>>>>
>>>> change log of v6:
>>>>   [RFC PATCH v6 12/19]
>>>>     * fix building error on other archtitectures than x86
>>>>
>>>>   [RFC PATCH v6 15-16/19]
>>>>     * fix building error on other archtitectures than x86
>>>>
>>>> change log of v5:
>>>>   * merge the patchset to clear page table and the patchset to hot remove
>>>>     memory(from ishimatsu) to one big patchset.
>>>>
>>>>   [RFC PATCH v5 1/19]
>>>>     * rename remove_memory() to offline_memory()/offline_pages()
>>>>
>>>>   [RFC PATCH v5 2/19]
>>>>     * new patch: implement offline_memory(). This function offlines pages,
>>>>       update memory block's state, and notify the userspace that the memory
>>>>       block's state is changed.
>>>>
>>>>   [RFC PATCH v5 4/19]
>>>>     * offline and remove memory in acpi_memory_disable_device() too.
>>>>
>>>>   [RFC PATCH v5 17/19]
>>>>     * new patch: add a new function __remove_zone() to revert the things done
>>>>       in the function __add_zone().
>>>>
>>>>   [RFC PATCH v5 18/19]
>>>>     * flush work befor reseting node device.
>>>>
>>>> change log of v4:
>>>>   * remove "memory-hotplug : unify argument of firmware_map_add_early/hotplug"
>>>>     from the patch series, since the patch is a bugfix. It is being disccussed
>>>>     on other thread. But for testing the patch series, the patch is needed.
>>>>     So I added the patch as [PATCH 0/13].
>>>>
>>>>   [RFC PATCH v4 2/13]
>>>>     * check memory is online or not at remove_memory()
>>>>     * add memory_add_physaddr_to_nid() to acpi_memory_device_remove() for
>>>>       getting node id
>>>>   [RFC PATCH v4 3/13]
>>>>     * create new patch : check memory is online or not at online_pages()
>>>>
>>>>   [RFC PATCH v4 4/13]
>>>>     * add __ref section to remove_memory()
>>>>     * call firmware_map_remove_entry() before remove_sysfs_fw_map_entry()
>>>>
>>>>   [RFC PATCH v4 11/13]
>>>>     * rewrite register_page_bootmem_memmap() for removing page used as PT/PMD
>>>>
>>>> change log of v3:
>>>>   * rebase to 3.5.0-rc6
>>>>
>>>>   [RFC PATCH v2 2/13]
>>>>     * remove extra kobject_put()
>>>>
>>>>     * The patch was commented by Wen. Wen's comment is
>>>>       "acpi_memory_device_remove() should ignore a return value of
>>>>       remove_memory() since caller does not care the return value".
>>>>       But I did not change it since I think caller should care the
>>>>       return value. And I am trying to fix it as follow:
>>>>
>>>>       https://lkml.org/lkml/2012/7/5/624
>>>>
>>>>   [RFC PATCH v2 4/13]
>>>>     * remove a firmware_memmap_entry allocated by kzmalloc()
>>>>
>>>> change log of v2:
>>>>   [RFC PATCH v2 2/13]
>>>>     * check whether memory block is offline or not before calling offline_memory()
>>>>     * check whether section is valid or not in is_memblk_offline()
>>>>     * call kobject_put() for each memory_block in is_memblk_offline()
>>>>
>>>>   [RFC PATCH v2 3/13]
>>>>     * unify the end argument of firmware_map_add_early/hotplug
>>>>
>>>>   [RFC PATCH v2 4/13]
>>>>     * add release_firmware_map_entry() for freeing firmware_map_entry
>>>>
>>>>   [RFC PATCH v2 6/13]
>>>>    * add release_memory_block() for freeing memory_block
>>>>
>>>>   [RFC PATCH v2 11/13]
>>>>    * fix wrong arguments of free_pages()
>>>>
>>>>
>>>> Wen Congyang (8):
>>>>    memory-hotplug: implement offline_memory()
>>>>    memory-hotplug: store the node id in acpi_memory_device
>>>>    memory-hotplug: export the function acpi_bus_remove()
>>>>    memory-hotplug: call acpi_bus_remove() to remove memory device
>>>>    memory-hotplug: introduce new function arch_remove_memory()
>>>>    memory-hotplug: remove sysfs file of node
>>>>    memory-hotplug: clear hwpoisoned flag when onlining pages
>>>>    memory-hotplug: auto offline page_cgroup when onlining memory block
>>>>      failed
>>>>
>>>> Yasuaki Ishimatsu (13):
>>>>    memory-hotplug: rename remove_memory() to
>>>>      offline_memory()/offline_pages()
>>>>    memory-hotplug: offline and remove memory when removing the memory
>>>>      device
>>>>    memory-hotplug: check whether memory is present or not
>>>>    memory-hotplug: remove /sys/firmware/memmap/X sysfs
>>>>    memory-hotplug: does not release memory region in PAGES_PER_SECTION
>>>>      chunks
>>>>    memory-hotplug: add memory_block_release
>>>>    memory-hotplug: remove_memory calls __remove_pages
>>>>    memory-hotplug: check page type in get_page_bootmem
>>>>    memory-hotplug: move register_page_bootmem_info_node and
>>>>      put_page_bootmem for sparse-vmemmap
>>>>    memory-hotplug: implement register_page_bootmem_info_section of
>>>>      sparse-vmemmap
>>>>    memory-hotplug: free memmap of sparse-vmemmap
>>>>    memory_hotplug: clear zone when the memory is removed
>>>>    memory-hotplug: add node_device_release
>>>>
>>>>   arch/ia64/mm/discontig.c                        |   14 +
>>>>   arch/ia64/mm/init.c                             |   16 +
>>>>   arch/powerpc/mm/init_64.c                       |   14 +
>>>>   arch/powerpc/mm/mem.c                           |   14 +
>>>>   arch/powerpc/platforms/pseries/hotplug-memory.c |   16 +-
>>>>   arch/s390/mm/init.c                             |   12 +
>>>>   arch/s390/mm/vmem.c                             |   14 +
>>>>   arch/sh/mm/init.c                               |   15 +
>>>>   arch/sparc/mm/init_64.c                         |   14 +
>>>>   arch/tile/mm/init.c                             |    8 +
>>>>   arch/x86/include/asm/pgtable_types.h            |    1 +
>>>>   arch/x86/mm/init_32.c                           |   10 +
>>>>   arch/x86/mm/init_64.c                           |  331 ++++++++++++++++++
>>>>   arch/x86/mm/pageattr.c                          |   47 ++--
>>>>   drivers/acpi/acpi_memhotplug.c                  |   54 +++-
>>>>   drivers/acpi/scan.c                             |    3 +-
>>>>   drivers/base/memory.c                           |   88 ++++-
>>>>   drivers/base/node.c                             |   11 +
>>>>   drivers/firmware/memmap.c                       |   98 +++++-
>>>>   include/acpi/acpi_bus.h                         |    1 +
>>>>   include/linux/firmware-map.h                    |    6 +
>>>>   include/linux/memory.h                          |    5 +
>>>>   include/linux/memory_hotplug.h                  |   25 +-
>>>>   include/linux/mm.h                              |    5 +-
>>>>   include/linux/mmzone.h                          |   19 +
>>>>   mm/memory_hotplug.c                             |  424 +++++++++++++++++++++--
>>>>   mm/page_cgroup.c                                |    3 +
>>>>   mm/sparse.c                                     |    5 +-
>>>>   28 files changed, 1181 insertions(+), 92 deletions(-)
>>>>
>>>> --
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>>>
>>
>>
>>
>