mm/mm_init.c: do not calculate zone_start_pfn/zone_end_pfn in zone_absent_pages_in_node()

In calculate_node_totalpages(), zone_start_pfn/zone_end_pfn are already
calculated in zone_spanned_pages_in_node(), so use them as parameters
instead of node_start_pfn/node_end_pfn and the duplicated calculation
process can de dropped.

Link: https://lkml.kernel.org/r/20230526085251.1977-2-haifeng.xu@shopee.comSigned-off-by: Haifeng Xu <haifeng.xu@shopee.com>
Suggested-by: Mike Rapoport <rppt@kernel.org>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Haifeng Xu <haifeng.xu@shopee.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/mm_init.c

@@ -1168,20 +1168,15 @@ unsigned long __init absent_pages_in_range(unsigned long start_pfn,
 /* Return the number of page frames in holes in a zone on a node */
 static unsigned long __init zone_absent_pages_in_node(int nid,
 					unsigned long zone_type,
-					unsigned long node_start_pfn,
-					unsigned long node_end_pfn)
+					unsigned long zone_start_pfn,
+					unsigned long zone_end_pfn)
 {
-	unsigned long zone_low = arch_zone_lowest_possible_pfn[zone_type];
-	unsigned long zone_high = arch_zone_highest_possible_pfn[zone_type];
-	unsigned long zone_start_pfn, zone_end_pfn;
 	unsigned long nr_absent;
 
-	zone_start_pfn = clamp(node_start_pfn, zone_low, zone_high);
-	zone_end_pfn = clamp(node_end_pfn, zone_low, zone_high);
+	/* zone is empty, we don't have any absent pages */
+	if (zone_start_pfn == zone_end_pfn)
+		return 0;
 
-	adjust_zone_range_for_zone_movable(nid, zone_type,
-			node_start_pfn, node_end_pfn,
-			&zone_start_pfn, &zone_end_pfn);
 	nr_absent = __absent_pages_in_range(nid, zone_start_pfn, zone_end_pfn);
 
 	/*
@@ -1274,7 +1269,7 @@ static void __init calculate_node_totalpages(struct pglist_data *pgdat,
 		struct zone *zone = pgdat->node_zones + i;
 		unsigned long zone_start_pfn, zone_end_pfn;
 		unsigned long spanned, absent;
-		unsigned long size, real_size;
+		unsigned long real_size;
 
 		spanned = zone_spanned_pages_in_node(pgdat->node_id, i,
 						     node_start_pfn,
@@ -1282,23 +1277,22 @@ static void __init calculate_node_totalpages(struct pglist_data *pgdat,
 						     &zone_start_pfn,
 						     &zone_end_pfn);
 		absent = zone_absent_pages_in_node(pgdat->node_id, i,
-						   node_start_pfn,
-						   node_end_pfn);
+						   zone_start_pfn,
+						   zone_end_pfn);
 
-		size = spanned;
-		real_size = size - absent;
+		real_size = spanned - absent;
 
-		if (size)
+		if (spanned)
 			zone->zone_start_pfn = zone_start_pfn;
 		else
 			zone->zone_start_pfn = 0;
-		zone->spanned_pages = size;
+		zone->spanned_pages = spanned;
 		zone->present_pages = real_size;
 #if defined(CONFIG_MEMORY_HOTPLUG)
 		zone->present_early_pages = real_size;
 #endif
 
-		totalpages += size;
+		totalpages += spanned;
 		realtotalpages += real_size;
 	}