mm/mm_init.c: get the highest zone directly

We have recorded nr_zones in pgdat, just get it directly.

Signed-off-by: Wei Yang <[email protected]>
Reviewed-by: Mike Rapoport (IBM) <[email protected]>
Link: https://lore.kernel.org/all/[email protected]
Signed-off-by: Mike Rapoport (IBM) <[email protected]>

Author: RichardWeiYang

mm/mm_init.c

@@ -2140,7 +2140,7 @@ static int __init deferred_init_memmap(void *data)
 	unsigned long first_init_pfn, flags;
 	unsigned long start = jiffies;
 	struct zone *zone;
-	int zid, max_threads;
+	int max_threads;
 	u64 i;
 
 	/* Bind memory initialisation thread to a local node if possible */
@@ -2167,12 +2167,8 @@ static int __init deferred_init_memmap(void *data)
 	 */
 	pgdat_resize_unlock(pgdat, &flags);
 
-	/* Only the highest zone is deferred so find it */
-	for (zid = 0; zid < MAX_NR_ZONES; zid++) {
-		zone = pgdat->node_zones + zid;
-		if (first_init_pfn < zone_end_pfn(zone))
-			break;
-	}
+	/* Only the highest zone is deferred */
+	zone = pgdat->node_zones + pgdat->nr_zones - 1;
 
 	/* If the zone is empty somebody else may have cleared out the zone */
 	if (!deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn,
@@ -2200,7 +2196,7 @@ static int __init deferred_init_memmap(void *data)
 	}
 zone_empty:
 	/* Sanity check that the next zone really is unpopulated */
-	WARN_ON(++zid < MAX_NR_ZONES && populated_zone(++zone));
+	WARN_ON(pgdat->nr_zones < MAX_NR_ZONES && populated_zone(++zone));
 
 	pr_info("node %d deferred pages initialised in %ums\n",
 		pgdat->node_id, jiffies_to_msecs(jiffies - start));