linux-master/mm/sparse.c

24  * 1) mem_section	- memory sections, mem_map's for valid memory
114  * mem_map, we use section_mem_map to store the section's NUMA
116  * node information is cleared just before we store the real mem_map.
275  * Subtle, we encode the real pfn into the mem_map such that
279 static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long pnum)
282 		(unsigned long)(mem_map - (section_nr_to_pfn(pnum)));
290  * Decode mem_map from the coded memmap
301 		unsigned long pnum, struct page *mem_map,
305 	ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum)
555  * Allocate the accumulated non-linear sections, allocate a mem_map