mm/page_owner: simplify zone iteration logic in init_early_allocated_pages()

The current implementation uses nested loops: first iterating over all
online nodes, then over zones within each node.  This can be simplified by
using the for_each_populated_zone() macro which directly iterates through
all populated zones.

This change:
1. Removes the intermediate init_zones_in_node() function
2. Simplifies init_early_allocated_pages() to use direct zone iteration
3. Updates init_pages_in_zone() to take only zone parameter and access
   node_id via zone->zone_pgdat

The functionality remains identical, but the code is cleaner and more
maintainable.

Link: https://lkml.kernel.org/r/20250930092153.843109-2-husong@kylinos.cn
Signed-off-by: Song Hu <husong@kylinos.cn>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Ye Liu <liuye@kylinos.cn>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/page_owner.c b/mm/page_owner.c
index 8ebc2de1c110981fd56c9fae7052c19367e53b76..a702456842061b4be7b4c7a45d8431e8745b7ef6 100644 (file)
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -769,7 +769,7 @@ static loff_t lseek_page_owner(struct file *file, loff_t offset, int orig)
        return file->f_pos;
 }
 
-static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
+static void init_pages_in_zone(struct zone *zone)
 {
        unsigned long pfn = zone->zone_start_pfn;
        unsigned long end_pfn = zone_end_pfn(zone);
@@ -836,28 +836,15 @@ ext_put_continue:
        }
 
        pr_info("Node %d, zone %8s: page owner found early allocated %lu pages\n",
-               pgdat->node_id, zone->name, count);
-}
-
-static void init_zones_in_node(pg_data_t *pgdat)
-{
-       struct zone *zone;
-       struct zone *node_zones = pgdat->node_zones;
-
-       for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
-               if (!populated_zone(zone))
-                       continue;
-
-               init_pages_in_zone(pgdat, zone);
-       }
+               zone->zone_pgdat->node_id, zone->name, count);
 }
 
 static void init_early_allocated_pages(void)
 {
-       pg_data_t *pgdat;
+       struct zone *zone;
 
-       for_each_online_pgdat(pgdat)
-               init_zones_in_node(pgdat);
+       for_each_populated_zone(zone)
+               init_pages_in_zone(zone);
 }
 
 static const struct file_operations page_owner_fops = {