Re: [RFC PATCH 0/4] mm/hotplug: make hotplug memory_block alligned

[Wei Yang <richard.weiyang@gmail.com>]

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On Mon, Jun 26, 2017 at 09:46:35AM +0200, Michal Hocko wrote:
>On Sun 25-06-17 10:52:23, Wei Yang wrote:
>> Michal & all
>> 
>> Previously we found the hotplug range is mem_section aligned instead of
>> memory_block.
>> 
>> Here is several draft patches to fix that. To make sure I am getting your
>> point correctly, I post it here before further investigation.
>
>This description doesn't explain what the problem is and why do we want
>to fix it. Before diving into the code and review changes it would help
>a lot to give a short introduction and explain your intention and your
>assumptions you base your changes on.
>
>So please start with a highlevel description first.
>

Here is the high level description in my mind, glad to see your comment.


The minimum unit of memory hotplug is memory_block instead of mem_section.
While in current implementation, we see several concept misunderstanding.

For example:
1. The alignment check is based on mem_section instead of memory_block
2. Online memory range on section base instead of memory_block base

Even memory_block and mem_section are close related, they are two concepts. It
is possible to initialize and register them respectively.

For example:
1. In __add_section(), it tries to register these two in one place.

This patch generally does the following:
1. Aligned the range with memory_block
2. Online rage with memory_block base
3. Split the registration of memory_block and mem_section



-- 
Wei Yang
Help you, Help me

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