Re: [PATCH v3 2/4] mm/sparsemem: Defer the ms->section_mem_map clearing

[Dave Hansen]

On 04/07/2018 11:50 PM, Baoquan He wrote:
>> Should the " = 0" instead be clearing SECTION_MARKED_PRESENT or
>> something?  That would make it easier to match the code up with the code
>> that it is effectively undoing.
> 
> Not sure if I understand your question correctly. From memory_present(),
> information encoded into ms->section_mem_map including numa node,
> SECTION_IS_ONLINE and SECTION_MARKED_PRESENT. Not sure if it's OK to only
> clear SECTION_MARKED_PRESENT.  People may wrongly check SECTION_IS_ONLINE
> and do something on this memory section?

What is mean is that, instead of:

	
	ms->section_mem_map = 0;

we could literally do:

	ms->section_mem_map &= ~SECTION_MARKED_PRESENT;

That does the same thing in practice, but makes the _intent_ much more
clear.