Re: [PATCH v3 2/2] mm/sparse: start using sparse_init_nid(), and remove old code

[Dave Hansen <dave.hansen@intel.com>]

On 07/01/2018 07:04 PM, Pavel Tatashin wrote:
> +	for_each_present_section_nr(pnum_begin + 1, pnum_end) {
> +		int nid = sparse_early_nid(__nr_to_section(pnum_end));
>  
> +		if (nid == nid_begin) {
> +			map_count++;
>  			continue;
>  		}

> +		sparse_init_nid(nid_begin, pnum_begin, pnum_end, map_count);
> +		nid_begin = nid;
> +		pnum_begin = pnum_end;
> +		map_count = 1;
>  	}

Ugh, this is really hard to read.  Especially because the pnum "counter"
is called "pnum_end".

So, this is basically a loop that collects all of the adjacent sections
in a given single nid and then calls sparse_init_nid().  pnum_end in
this case is non-inclusive, so the sparse_init_nid() call is actually
for the *previous* nid that pnum_end is pointing _past_.

This *really* needs commenting.