if (!mem_section[pnum].section_mem_map) 
if (!valid_section_nr(pnum)) 
void sparse_init(void){	unsigned long pnum;	struct page *map;	int nid;	for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {		if (!mem_section[pnum].section_mem_map)			continue;		nid = early_pfn_to_nid(section_nr_to_pfn(pnum));		map = alloc_remap(nid, sizeof(struct page) * PAGES_PER_SECTION);		if (!map)			map = alloc_bootmem_node(NODE_DATA(nid),				sizeof(struct page) * PAGES_PER_SECTION);		if (!map) {			mem_section[pnum].section_mem_map = 0;			continue;		}		/*		 * Subtle, we encode the real pfn into the mem_map such that		 * the identity pfn - section_mem_map will return the actual		 * physical page frame number.		 */		mem_section[pnum].section_mem_map = map -						section_nr_to_pfn(pnum);	}}
4520	/local/tlutelli/issta_data/temp/c/2005_temp/2005/4520/29751f6991e845f7d002a6ae520bf996b38c8dcd/sparse.c/buggy/mm/sparse.c