NR_SECTION_ROOTS
extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
if (unlikely(root >= NR_SECTION_ROOTS))
VMCOREINFO_LENGTH(mem_section, NR_SECTION_ROOTS);
size = sizeof(struct mem_section *) * NR_SECTION_ROOTS;
struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]