+ mm-page_alloc-refactor-build_node_zonelist-out-of-build_zonelists.patch added to mm-new branch

+ mm-page_alloc-refactor-build_node_zonelist-out-of-build_zonelists.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: mm/page_alloc: refactor build_node_zonelist() out of build_zonelists()
has been added to the -mm mm-new branch.  Its filename is
     mm-page_alloc-refactor-build_node_zonelist-out-of-build_zonelists.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-page_alloc-refactor-build_node_zonelist-out-of-build_zonelists.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days

------------------------------------------------------
From: Gregory Price <gourry@gourry.net>
Subject: mm/page_alloc: refactor build_node_zonelist() out of build_zonelists()
Date: Fri, 11 Sep 2026 23:04:24 -0400

Extract per-node fallback-list construction into build_node_zonelist(). 
Build each selected node directly into the destination zonelist so no
intermediate node_order array or node count is needed.  Print the fallback
order as each node is added.

This lets us build new zonelists from candidate nodemasks instead of just
the default N_MEMORY node state list.

No functional change: build_zonelists() builds and prints the same
FALLBACK list over N_MEMORY with node_load updates as before.

Link: https://lore.kernel.org/20260912030424.2889731-3-gourry@gourry.net
Signed-off-by: Gregory Price <gourry@gourry.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Balbir Singh <balbirs@nvidia.com>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
---

 mm/page_alloc.c |   63 ++++++++++++++++------------------------------
 1 file changed, 23 insertions(+), 40 deletions(-)

--- a/mm/page_alloc.c~mm-page_alloc-refactor-build_node_zonelist-out-of-build_zonelists
+++ a/mm/page_alloc.c
@@ -5858,31 +5858,6 @@ int find_next_best_node_in(int node, nod
 
 
 /*
- * Build zonelists ordered by node and zones within node.
- * This results in maximum locality--normal zone overflows into local
- * DMA zone, if any--but risks exhausting DMA zone.
- */
-static void build_zonelists_in_node_order(pg_data_t *pgdat, int *node_order,
-		unsigned nr_nodes)
-{
-	struct zoneref *zonerefs;
-	int i;
-
-	zonerefs = pgdat->node_zonelists[ZONELIST_FALLBACK]._zonerefs;
-
-	for (i = 0; i < nr_nodes; i++) {
-		int nr_zones;
-
-		pg_data_t *node = NODE_DATA(node_order[i]);
-
-		nr_zones = build_zonerefs_node(node, zonerefs);
-		zonerefs += nr_zones;
-	}
-	zonerefs->zone = NULL;
-	zonerefs->zone_idx = 0;
-}
-
-/*
  * Build __GFP_THISNODE zonelists
  */
 static void build_thisnode_zonelists(pg_data_t *pgdat)
@@ -5897,20 +5872,24 @@ static void build_thisnode_zonelists(pg_
 	zonerefs->zone_idx = 0;
 }
 
-static void build_zonelists(pg_data_t *pgdat)
+/*
+ * Build one zonelist ordered by node and zones within node. This results in
+ * maximum locality--normal zone overflows into local DMA zone, if any--but
+ * risks exhausting DMA zone.
+ */
+static void build_node_zonelist(pg_data_t *pgdat, const nodemask_t *candidates,
+				int zlidx)
 {
-	static int node_order[MAX_NUMNODES];
-	int node, nr_nodes = 0;
+	struct zoneref *zonerefs = pgdat->node_zonelists[zlidx]._zonerefs;
 	nodemask_t used_mask = NODE_MASK_NONE;
-	int local_node, prev_node;
+	int local_node = pgdat->node_id;
+	int prev_node = local_node;
+	int node;
 
-	/* NUMA-aware ordering of nodes */
-	local_node = pgdat->node_id;
-	prev_node = local_node;
+	pr_info("Fallback order for Node %d: ", local_node);
 
-	memset(node_order, 0, sizeof(node_order));
 	while ((node = find_next_best_node_in(local_node, &used_mask,
-					      &node_states[N_MEMORY])) >= 0) {
+					      candidates)) >= 0) {
 		/*
 		 * We don't want to pressure a particular node.
 		 * So adding penalty to the first node in same
@@ -5920,18 +5899,22 @@ static void build_zonelists(pg_data_t *p
 		    node_distance(local_node, prev_node))
 			node_load[node] += 1;
 
-		node_order[nr_nodes++] = node;
+		zonerefs += build_zonerefs_node(NODE_DATA(node), zonerefs);
+		pr_cont("%d ", node);
 		prev_node = node;
 	}
 
-	build_zonelists_in_node_order(pgdat, node_order, nr_nodes);
-	build_thisnode_zonelists(pgdat);
-	pr_info("Fallback order for Node %d: ", local_node);
-	for (node = 0; node < nr_nodes; node++)
-		pr_cont("%d ", node_order[node]);
+	zonerefs->zone = NULL;
+	zonerefs->zone_idx = 0;
 	pr_cont("\n");
 }
 
+static void build_zonelists(pg_data_t *pgdat)
+{
+	build_node_zonelist(pgdat, &node_states[N_MEMORY], ZONELIST_FALLBACK);
+	build_thisnode_zonelists(pgdat);
+}
+
 #ifdef CONFIG_HAVE_MEMORYLESS_NODES
 /*
  * Return node id of node used for "local" allocations.
_

Patches currently in -mm which might be from gourry@gourry.net are

mm-mempolicy-take-a-cpuset-cookie-for-the-interleave-node-count.patch
mm-mempolicy-use-srcu-for-the-weighted-interleave-state.patch
mm-mempolicy-stop-copying-the-nodemask-in-the-interleave-paths.patch
mm-huge_memory-skip-zone-device-folios-in-madvise_free_huge_pmd.patch
mm-madvise-skip-zone-device-folios-in-cold-pageout-pmd-range.patch
mm-mempolicy-skip-zone-device-folios-when-queueing-folios.patch
mm-memory_hotplug-factor-out-node_is_memoryless.patch
mm-mempolicy-use-vm_normal_folio_pmd-in-queue_folios_pmd.patch
mm-madvise-use-vm_normal_folio_pmd-in-cold-pageout-pmd-range.patch
mm-refactor-find_next_best_node-to-find_next_best_node_in.patch
mm-page_alloc-refactor-build_node_zonelist-out-of-build_zonelists.patch