Re: [PATCH] x86/mm: Remove the redundant conditional check

[Baoquan He]

On 03/10/20 at 11:10am, Michal Hocko wrote:
> On Sun 08-03-20 09:35:11, Baoquan He wrote:
> > In commit f70029bbaacbfa8f0 ("mm, memory_hotplug: drop CONFIG_MOVABLE_NODE"),
> > the dependency on CONFIG_MOVABLE_NODE was removed for N_MEMORY, so the
> > conditional check in paging_init() doesn't make any sense any more.
> > Remove it.
> 
> Please expand more. I would really have to refresh the intention of the
> code but from a quick look at the code CONFIG_HIGHMEM still makes
> N_MEMORY != N_NORMAL_MEMORY. So what what does this change mean for that
> config?

Thanks for looking into this. I was trying to explain that
CONFIG_MOVABLE_NODE made N_MEMORY have chance to take different enum
value.
 
Do you think the below saying is OK to you?
 
~~~
In commit f70029bbaacb ("mm, memory_hotplug: drop CONFIG_MOVABLE_NODE"),
the dependency on CONFIG_MOVABLE_NODE was removed for N_MEMORY.  Before
commit f70029bbaacb, CONFIG_HIGHMEM && !CONFIG_MOVABLE_NODE could make
(N_MEMORY == N_NORMAL_MEMORY) be true. After commit f70029bbaacb, N_MEMORY
doesn't have any chance to be equal to N_NORMAL_MEMORY. So the  conditional
check in paging_init() doesn't make any sense any more. Let's remove it.
~~~
 
Thanks
Baoquan