[PATCH v3 4/7] hugetlb: pass *next_nid_to_alloc directly to for_each_node_mask_to_alloc

[Gang Li <gang.li@linux.dev>]

The parallelization of hugetlb allocation leads to errors when sharing
h->next_nid_to_alloc across different threads. To address this, it's
necessary to assign a separate next_nid_to_alloc for each thread.

Consequently, the hstate_next_node_to_alloc and for_each_node_mask_to_alloc
have been modified to directly accept a *next_nid_to_alloc parameter,
ensuring thread-specific allocation and avoiding concurrent access issues.

Signed-off-by: Gang Li <gang.li@linux.dev>
---
This patch seems not elegant, but I can't come up with anything better.
Any suggestions will be highly appreciated!
---
 mm/hugetlb.c | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 92448e747991d..a71bc1622b53b 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1464,15 +1464,15 @@ static int get_valid_node_allowed(int nid, nodemask_t *nodes_allowed)
  * next node from which to allocate, handling wrap at end of node
  * mask.
  */
-static int hstate_next_node_to_alloc(struct hstate *h,
+static int hstate_next_node_to_alloc(int *next_nid_to_alloc,
 					nodemask_t *nodes_allowed)
 {
 	int nid;
 
 	VM_BUG_ON(!nodes_allowed);
 
-	nid = get_valid_node_allowed(h->next_nid_to_alloc, nodes_allowed);
-	h->next_nid_to_alloc = next_node_allowed(nid, nodes_allowed);
+	nid = get_valid_node_allowed(*next_nid_to_alloc, nodes_allowed);
+	*next_nid_to_alloc = next_node_allowed(nid, nodes_allowed);
 
 	return nid;
 }
@@ -1495,10 +1495,10 @@ static int hstate_next_node_to_free(struct hstate *h, nodemask_t *nodes_allowed)
 	return nid;
 }
 
-#define for_each_node_mask_to_alloc(hs, nr_nodes, node, mask)		\
+#define for_each_node_mask_to_alloc(next_nid_to_alloc, nr_nodes, node, mask)		\
 	for (nr_nodes = nodes_weight(*mask);				\
 		nr_nodes > 0 &&						\
-		((node = hstate_next_node_to_alloc(hs, mask)) || 1);	\
+		((node = hstate_next_node_to_alloc(next_nid_to_alloc, mask)) || 1);	\
 		nr_nodes--)
 
 #define for_each_node_mask_to_free(hs, nr_nodes, node, mask)		\
@@ -2350,12 +2350,13 @@ static void prep_and_add_allocated_folios(struct hstate *h,
  */
 static struct folio *alloc_pool_huge_folio(struct hstate *h,
 					nodemask_t *nodes_allowed,
-					nodemask_t *node_alloc_noretry)
+					nodemask_t *node_alloc_noretry,
+					int *next_nid_to_alloc)
 {
 	gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE;
 	int nr_nodes, node;
 
-	for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
+	for_each_node_mask_to_alloc(next_nid_to_alloc, nr_nodes, node, nodes_allowed) {
 		struct folio *folio;
 
 		folio = only_alloc_fresh_hugetlb_folio(h, gfp_mask, node,
@@ -3310,7 +3311,7 @@ int __alloc_bootmem_huge_page(struct hstate *h, int nid)
 		goto found;
 	}
 	/* allocate from next node when distributing huge pages */
-	for_each_node_mask_to_alloc(h, nr_nodes, node, &node_states[N_MEMORY]) {
+	for_each_node_mask_to_alloc(&h->next_nid_to_alloc, nr_nodes, node, &node_states[N_MEMORY]) {
 		m = memblock_alloc_try_nid_raw(
 				huge_page_size(h), huge_page_size(h),
 				0, MEMBLOCK_ALLOC_ACCESSIBLE, node);
@@ -3684,7 +3685,7 @@ static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
 	VM_BUG_ON(delta != -1 && delta != 1);
 
 	if (delta < 0) {
-		for_each_node_mask_to_alloc(h, nr_nodes, node, nodes_allowed) {
+		for_each_node_mask_to_alloc(&h->next_nid_to_alloc, nr_nodes, node, nodes_allowed) {
 			if (h->surplus_huge_pages_node[node])
 				goto found;
 		}
@@ -3799,7 +3800,8 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid,
 		cond_resched();
 
 		folio = alloc_pool_huge_folio(h, nodes_allowed,
-						node_alloc_noretry);
+						node_alloc_noretry,
+						&h->next_nid_to_alloc);
 		if (!folio) {
 			prep_and_add_allocated_folios(h, &page_list);
 			spin_lock_irq(&hugetlb_lock);
-- 
2.20.1