find_next_best_node() picks the next-closest node for a fallback list
from the full N_MEMORY set. Refactor it into find_next_best_node_in(),
which takes an explicit candidates nodemask.

This enables building fallback lists with non-N_MEMORY candidates.

No functional change: every caller still selects from N_MEMORY.

Signed-off-by: Gregory Price <[email protected]>
---
 mm/internal.h     |  6 ++++--
 mm/memory-tiers.c |  7 ++++---
 mm/page_alloc.c   | 13 ++++++++-----
 3 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/mm/internal.h b/mm/internal.h
index f26423de4ca28..96d78a7778e88 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1103,7 +1103,8 @@ extern int node_reclaim_mode;
 
 extern unsigned long node_reclaim(struct pglist_data *pgdat,
                                  gfp_t gfp_mask, unsigned int order);
-extern int find_next_best_node(int node, nodemask_t *used_node_mask);
+extern int find_next_best_node_in(int node, nodemask_t *used_node_mask,
+                                 const nodemask_t *candidates);
 #else
 #define node_reclaim_mode 0
 
@@ -1112,7 +1113,8 @@ static inline unsigned long node_reclaim(struct 
pglist_data *pgdat,
 {
        return 0;
 }
-static inline int find_next_best_node(int node, nodemask_t *used_node_mask)
+static inline int find_next_best_node_in(int node, nodemask_t *used_node_mask,
+                                        const nodemask_t *candidates)
 {
        return NUMA_NO_NODE;
 }
diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c
index 54851d8a195b0..25e121851b586 100644
--- a/mm/memory-tiers.c
+++ b/mm/memory-tiers.c
@@ -370,7 +370,7 @@ int next_demotion_node(int node, const nodemask_t 
*allowed_mask)
         * closest demotion target.
         */
        nodes_complement(mask, *allowed_mask);
-       return find_next_best_node(node, &mask);
+       return find_next_best_node_in(node, &mask, &node_states[N_MEMORY]);
 }
 
 static void disable_all_demotion_targets(void)
@@ -450,7 +450,7 @@ static void establish_demotion_targets(void)
                memtier = list_next_entry(memtier, list);
                tier_nodes = get_memtier_nodemask(memtier);
                /*
-                * find_next_best_node, use 'used' nodemask as a skip list.
+                * find_next_best_node_in, use 'used' nodemask as a skip list.
                 * Add all memory nodes except the selected memory tier
                 * nodelist to skip list so that we find the best node from the
                 * memtier nodelist.
@@ -463,7 +463,8 @@ static void establish_demotion_targets(void)
                 * in the preferred mask when allocating pages during demotion.
                 */
                do {
-                       target = find_next_best_node(node, &tier_nodes);
+                       target = find_next_best_node_in(node, &tier_nodes,
+                                                       &node_states[N_MEMORY]);
                        if (target == NUMA_NO_NODE)
                                break;
 
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f93a6bb9a872d..acf096f525f49 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5743,9 +5743,10 @@ static int numa_zonelist_order_handler(const struct 
ctl_table *table, int write,
 static int node_load[MAX_NUMNODES];
 
 /**
- * find_next_best_node - find the next node that should appear in a given 
node's fallback list
+ * find_next_best_node_in - find the next node that should appear in a given 
node's fallback list
  * @node: node whose fallback list we're appending
  * @used_node_mask: nodemask_t of already used nodes
+ * @candidates: nodemask_t of nodes eligible for selection
  *
  * We use a number of factors to determine which is the next node that should
  * appear on a given node's fallback list.  The node should not have appeared
@@ -5757,7 +5758,8 @@ static int node_load[MAX_NUMNODES];
  *
  * Return: node id of the found node or %NUMA_NO_NODE if no node is found.
  */
-int find_next_best_node(int node, nodemask_t *used_node_mask)
+int find_next_best_node_in(int node, nodemask_t *used_node_mask,
+                          const nodemask_t *candidates)
 {
        int n, val;
        int min_val = INT_MAX;
@@ -5767,12 +5769,12 @@ int find_next_best_node(int node, nodemask_t 
*used_node_mask)
         * Use the local node if we haven't already, but for memoryless local
         * node, we should skip it and fall back to other nodes.
         */
-       if (!node_isset(node, *used_node_mask) && node_state(node, N_MEMORY)) {
+       if (!node_isset(node, *used_node_mask) && node_isset(node, 
*candidates)) {
                node_set(node, *used_node_mask);
                return node;
        }
 
-       for_each_node_state(n, N_MEMORY) {
+       for_each_node_mask(n, *candidates) {
 
                /* Don't want a node to appear more than once */
                if (node_isset(n, *used_node_mask))
@@ -5857,7 +5859,8 @@ static void build_zonelists(pg_data_t *pgdat)
        prev_node = local_node;
 
        memset(node_order, 0, sizeof(node_order));
-       while ((node = find_next_best_node(local_node, &used_mask)) >= 0) {
+       while ((node = find_next_best_node_in(local_node, &used_mask,
+                                             &node_states[N_MEMORY])) >= 0) {
                /*
                 * We don't want to pressure a particular node.
                 * So adding penalty to the first node in same
-- 
2.53.0-Meta


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