mm/page_alloc.c: remove unneeded codes in !NUMA version of build_zonelists()

When CONFIG_NUMA=n, MAX_NUMNODES is always 1 because Kconfig item
NODES_SHIFT depends on NUMA.  So in !NUMA version of build_zonelists(), no
need to bother with the two for loop because code execution won't enter
them ever.

Here, remove those unneeded codes in !NUMA version of build_zonelists().

[bhe@redhat.com: remove unused locals]
Link: https://lkml.kernel.org/r/ZgQL1WOf9K88nLpQ@MiWiFi-R3L-srv
Link: https://lkml.kernel.org/r/20240326061134.1055295-5-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: "Mike Rapoport (IBM)" <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6a8593aef297769e8e15ee969097b45e39a9d679..d932f406c0c1aa0a2bb19d0665a41409932ee66d 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5280,37 +5280,13 @@ static void setup_min_slab_ratio(void);
 
 static void build_zonelists(pg_data_t *pgdat)
 {
-       int node, local_node;
        struct zoneref *zonerefs;
        int nr_zones;
 
-       local_node = pgdat->node_id;
-
        zonerefs = pgdat->node_zonelists[ZONELIST_FALLBACK]._zonerefs;
        nr_zones = build_zonerefs_node(pgdat, zonerefs);
        zonerefs += nr_zones;
 
-       /*
-        * Now we build the zonelist so that it contains the zones
-        * of all the other nodes.
-        * We don't want to pressure a particular node, so when
-        * building the zones for node N, we make sure that the
-        * zones coming right after the local ones are those from
-        * node N+1 (modulo N)
-        */
-       for (node = local_node + 1; node < MAX_NUMNODES; node++) {
-               if (!node_online(node))
-                       continue;
-               nr_zones = build_zonerefs_node(NODE_DATA(node), zonerefs);
-               zonerefs += nr_zones;
-       }
-       for (node = 0; node < local_node; node++) {
-               if (!node_online(node))
-                       continue;
-               nr_zones = build_zonerefs_node(NODE_DATA(node), zonerefs);
-               zonerefs += nr_zones;
-       }
-
        zonerefs->zone = NULL;
        zonerefs->zone_idx = 0;
 }