Subject: Re: [PATCH v2 00/12] memory-hotplug: hot-remove physical memory

From: Ni zhan Chen <[email-masked]>
Date: Tue, 23 Oct 2012 18:30:05 +0800

On 10/23/2012 06:30 PM, [email-masked] wrote:
> From: Wen Congyang <[email-masked]>

The patchset doesn't support kernel memory hot-remove, correct? If the 
answer is yes, you should point out in your patchset changelog.

>
> The patch-set was divided from following thread's patch-set.
>
> https://lkml.org/lkml/2012/9/5/201
>
> The last version of this patchset:
> https://lkml.org/lkml/2012/10/5/469
>
> If you want to know the reason, please read following thread.
>
> https://lkml.org/lkml/2012/10/2/83
>
> The patch-set has only the function of kernel core side for physical
> memory hot remove. So if you use the patch, please apply following
> patches.
>
> - bug fix for memory hot remove
>    https://lkml.org/lkml/2012/10/19/56
>    
> - acpi framework
>    https://lkml.org/lkml/2012/10/19/156
>
> The patches can free/remove the following things:
>
>    - /sys/firmware/memmap/X/{end, start, type} : [PATCH 2/10]
>    - mem_section and related sysfs files       : [PATCH 3-4/10]
>    - memmap of sparse-vmemmap                  : [PATCH 5-7/10]
>    - page table of removed memory              : [RFC PATCH 8/10]
>    - node and related sysfs files              : [RFC PATCH 9-10/10]
>
> * [PATCH 2/10] checks whether the memory can be removed or not.
>
> 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
> 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. 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
>
>
> Changelogs from v1 to v2:
>   Patch1: new patch, offline memory twice. 1st iterate: offline every non primary
>           memory block. 2nd iterate: offline primary (i.e. first added) memory
>           block.
>
>   Patch3: new patch, no logical change, just remove reduntant codes.
>
>   Patch9: merge the patch from wujianguo into this patch. flush tlb on all cpu
>           after the pagetable is changed.
>
>   Patch12: new patch, free node_data when a node is offlined
>
> Wen Congyang (6):
>    memory-hotplug: try to offline the memory twice to avoid dependence
>    memory-hotplug: remove redundant codes
>    memory-hotplug: introduce new function arch_remove_memory() for
>      removing page table depends on architecture
>    memory-hotplug: remove page table of x86_64 architecture
>    memory-hotplug: remove sysfs file of node
>    memory-hotplug: free node_data when a node is offlined
>
> Yasuaki Ishimatsu (6):
>    memory-hotplug: check whether all memory blocks are offlined or not
>      when removing memory
>    memory-hotplug: remove /sys/firmware/memmap/X sysfs
>    memory-hotplug: unregister memory section on SPARSEMEM_VMEMMAP
>    memory-hotplug: implement register_page_bootmem_info_section of
>      sparse-vmemmap
>    memory-hotplug: remove memmap of sparse-vmemmap
>    memory-hotplug: memory_hotplug: clear zone when removing the memory
>
>   arch/ia64/mm/discontig.c             |   14 ++
>   arch/ia64/mm/init.c                  |   18 ++
>   arch/powerpc/mm/init_64.c            |   14 ++
>   arch/powerpc/mm/mem.c                |   12 +
>   arch/s390/mm/init.c                  |   12 +
>   arch/s390/mm/vmem.c                  |   14 ++
>   arch/sh/mm/init.c                    |   17 ++
>   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                |   12 +
>   arch/x86/mm/init_64.c                |  409 ++++++++++++++++++++++++++++++++++
>   arch/x86/mm/pageattr.c               |   47 ++--
>   drivers/acpi/acpi_memhotplug.c       |    8 +-
>   drivers/base/memory.c                |    6 +
>   drivers/firmware/memmap.c            |   98 ++++++++-
>   include/linux/firmware-map.h         |    6 +
>   include/linux/memory_hotplug.h       |   15 +-
>   include/linux/mm.h                   |    5 +-
>   mm/memory_hotplug.c                  |  409 ++++++++++++++++++++++++++++++++--
>   mm/sparse.c                          |    5 +-
>   21 files changed, 1087 insertions(+), 57 deletions(-)
>
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