Subject: Re: [PATCH v3 00/12] memory-hotplug: hot-remove physical memory

From: Yasuaki Ishimatsu <[email-masked]>
Date: Thu, 22 Nov 2012 10:33:32 +0900

Hi Andrew,

The patch-set aims to linux-3.8. So we would like you to merge
the patch-set into your tree.

The patch-set applied many comments. Currently there is no
comment to the patch-set.

Additionally, we have spent a lot of time on the verification
of the patch-set. And we found many bugs, and fixed them.

So we believe that Linux on x86_64 can support memory hot remove
by the patch-set. 

Thanks,
Yasuaki Ishimatsu

2012/11/01 18:44, Wen Congyang wrote:
> 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/2012/10/23/213
> 
> 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/2012/10/31/269
>    
> - acpi framework
>    https://lkml.org/lkml/2012/10/26/175
> 
> 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 v2 to v3:
>   Patch9: call sync_global_pgds() if pgd is changed
>   Patch10: fix a problem int the patch
> 
> 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                | 417 +++++++++++++++++++++++++++++++++++
>   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, 1095 insertions(+), 57 deletions(-)
>