Re: [PATCH] mm/mm_init: Don't iterate pages below ARCH_PFN_OFFSET

[kernel test robot <lkp@intel.com>]

Hi Ruihan,

kernel test robot noticed the following build errors:

[auto build test ERROR on akpm-mm/mm-everything]

url:    https://github.com/intel-lab-lkp/linux/commits/Ruihan-Li/mm-mm_init-Don-t-iterate-pages-below-ARCH_PFN_OFFSET/20250419-002910
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20250418162727.1535335-1-lrh2000%40pku.edu.cn
patch subject: [PATCH] mm/mm_init: Don't iterate pages below ARCH_PFN_OFFSET
config: s390-randconfig-002-20250419 (https://download.01.org/0day-ci/archive/20250419/202504191858.5WVRkO7O-lkp@intel.com/config)
compiler: s390-linux-gcc (GCC) 7.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250419/202504191858.5WVRkO7O-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202504191858.5WVRkO7O-lkp@intel.com/

All errors (new ones prefixed by >>):

   mm/mm_init.c: In function 'memmap_init':
>> mm/mm_init.c:975:27: error: 'ARCH_PFN_OFFSET' undeclared (first use in this function); did you mean 'PREEMPT_OFFSET'?
     unsigned long hole_pfn = ARCH_PFN_OFFSET;
                              ^~~~~~~~~~~~~~~
                              PREEMPT_OFFSET
   mm/mm_init.c:975:27: note: each undeclared identifier is reported only once for each function it appears in


vim +975 mm/mm_init.c

   971	
   972	static void __init memmap_init(void)
   973	{
   974		unsigned long start_pfn, end_pfn;
 > 975		unsigned long hole_pfn = ARCH_PFN_OFFSET;
   976		int i, j, zone_id = 0, nid;
   977	
   978		for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid) {
   979			struct pglist_data *node = NODE_DATA(nid);
   980	
   981			for (j = 0; j < MAX_NR_ZONES; j++) {
   982				struct zone *zone = node->node_zones + j;
   983	
   984				if (!populated_zone(zone))
   985					continue;
   986	
   987				memmap_init_zone_range(zone, start_pfn, end_pfn,
   988						       &hole_pfn);
   989				zone_id = j;
   990			}
   991		}
   992	
   993		/*
   994		 * Initialize the memory map for hole in the range [memory_end,
   995		 * section_end] for SPARSEMEM and in the range [memory_end, memmap_end]
   996		 * for FLATMEM.
   997		 * Append the pages in this hole to the highest zone in the last
   998		 * node.
   999		 */
  1000	#ifdef CONFIG_SPARSEMEM
  1001		end_pfn = round_up(end_pfn, PAGES_PER_SECTION);
  1002	#else
  1003		end_pfn = round_up(end_pfn, MAX_ORDER_NR_PAGES);
  1004	#endif
  1005		if (hole_pfn < end_pfn)
  1006			init_unavailable_range(hole_pfn, end_pfn, zone_id, nid);
  1007	}
  1008	

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