[PATCH RFC v2 08/18] mm: hugetlb: thread pghint_t through buddy allocation chain

[Michael S. Tsirkin]

Thread pghint_t *hints through the hugetlb buddy allocation path:
  alloc_buddy_frozen_folio -> only_alloc_fresh_hugetlb_folio

alloc_buddy_frozen_folio now calls __alloc_frozen_pages_hints()
so the reported-page zeroed hint can propagate up.

Add pghint_t *hints to alloc_hugetlb_folio_reserve() for the
memfd path.  Callers that do not need hints pass NULL.

No functional change yet: hints are threaded but not acted upon.

Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Assisted-by: Claude:claude-opus-4-6
Assisted-by: cursor-agent:GPT-5.4-xhigh
---
 include/linux/hugetlb.h |  6 ++++--
 mm/hugetlb.c            | 29 ++++++++++++++++++++---------
 mm/memfd.c              |  2 +-
 3 files changed, 25 insertions(+), 12 deletions(-)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 65910437be1c..7311ad87add4 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -710,7 +710,8 @@ struct folio *alloc_hugetlb_folio_nodemask(struct hstate *h, int preferred_nid,
 				nodemask_t *nmask, gfp_t gfp_mask,
 				bool allow_alloc_fallback);
 struct folio *alloc_hugetlb_folio_reserve(struct hstate *h, int preferred_nid,
-					  nodemask_t *nmask, gfp_t gfp_mask);
+				nodemask_t *nmask, gfp_t gfp_mask,
+				pghint_t *hints);
 
 int hugetlb_add_to_page_cache(struct folio *folio, struct address_space *mapping,
 			pgoff_t idx);
@@ -1124,7 +1125,8 @@ static inline struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma,
 
 static inline struct folio *
 alloc_hugetlb_folio_reserve(struct hstate *h, int preferred_nid,
-			    nodemask_t *nmask, gfp_t gfp_mask)
+			    nodemask_t *nmask, gfp_t gfp_mask,
+			    pghint_t *hints)
 {
 	return NULL;
 }
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 327eaa4074d3..faa94a114fd4 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1842,7 +1842,8 @@ struct address_space *hugetlb_folio_mapping_lock_write(struct folio *folio)
 }
 
 static struct folio *alloc_buddy_frozen_folio(int order, gfp_t gfp_mask,
-		int nid, nodemask_t *nmask, nodemask_t *node_alloc_noretry)
+		int nid, nodemask_t *nmask, nodemask_t *node_alloc_noretry,
+		pghint_t *hints)
 {
 	struct folio *folio;
 	bool alloc_try_hard = true;
@@ -1859,7 +1860,8 @@ static struct folio *alloc_buddy_frozen_folio(int order, gfp_t gfp_mask,
 	if (alloc_try_hard)
 		gfp_mask |= __GFP_RETRY_MAYFAIL;
 
-	folio = (struct folio *)__alloc_frozen_pages(gfp_mask, order, nid, nmask);
+	folio = (struct folio *)__alloc_frozen_pages_hints(gfp_mask, order,
+							  nid, nmask, hints);
 
 	/*
 	 * If we did not specify __GFP_RETRY_MAYFAIL, but still got a
@@ -1888,11 +1890,14 @@ static struct folio *alloc_buddy_frozen_folio(int order, gfp_t gfp_mask,
 
 static struct folio *only_alloc_fresh_hugetlb_folio(struct hstate *h,
 		gfp_t gfp_mask, int nid, nodemask_t *nmask,
-		nodemask_t *node_alloc_noretry)
+		nodemask_t *node_alloc_noretry, pghint_t *hints)
 {
 	struct folio *folio;
 	int order = huge_page_order(h);
 
+	if (hints)
+		*hints = 0;
+
 	if (nid == NUMA_NO_NODE)
 		nid = numa_mem_id();
 
@@ -1900,7 +1905,7 @@ static struct folio *only_alloc_fresh_hugetlb_folio(struct hstate *h,
 		folio = alloc_gigantic_frozen_folio(order, gfp_mask, nid, nmask);
 	else
 		folio = alloc_buddy_frozen_folio(order, gfp_mask, nid, nmask,
-						 node_alloc_noretry);
+						 node_alloc_noretry, hints);
 	if (folio)
 		init_new_hugetlb_folio(folio);
 	return folio;
@@ -1918,7 +1923,8 @@ static struct folio *alloc_fresh_hugetlb_folio(struct hstate *h,
 {
 	struct folio *folio;
 
-	folio = only_alloc_fresh_hugetlb_folio(h, gfp_mask, nid, nmask, NULL);
+	folio = only_alloc_fresh_hugetlb_folio(h, gfp_mask, nid, nmask,
+					      NULL, NULL);
 	if (folio)
 		hugetlb_vmemmap_optimize_folio(h, folio);
 	return folio;
@@ -1958,7 +1964,8 @@ static struct folio *alloc_pool_huge_folio(struct hstate *h,
 		struct folio *folio;
 
 		folio = only_alloc_fresh_hugetlb_folio(h, gfp_mask, node,
-					nodes_allowed, node_alloc_noretry);
+					nodes_allowed, node_alloc_noretry,
+					NULL);
 		if (folio)
 			return folio;
 	}
@@ -2231,10 +2238,13 @@ struct folio *alloc_buddy_hugetlb_folio_with_mpol(struct hstate *h,
 }
 
 struct folio *alloc_hugetlb_folio_reserve(struct hstate *h, int preferred_nid,
-		nodemask_t *nmask, gfp_t gfp_mask)
+		nodemask_t *nmask, gfp_t gfp_mask, pghint_t *hints)
 {
 	struct folio *folio;
 
+	if (hints)
+		*hints = (pghint_t)0;
+
 	spin_lock_irq(&hugetlb_lock);
 	if (!h->resv_huge_pages) {
 		spin_unlock_irq(&hugetlb_lock);
@@ -3434,13 +3444,14 @@ static void __init hugetlb_hstate_alloc_pages_onenode(struct hstate *h, int nid)
 			gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE;
 
 			folio = only_alloc_fresh_hugetlb_folio(h, gfp_mask, nid,
-					&node_states[N_MEMORY], NULL);
+					&node_states[N_MEMORY], NULL, NULL);
 			if (!folio && !list_empty(&folio_list) &&
 			    hugetlb_vmemmap_optimizable_size(h)) {
 				prep_and_add_allocated_folios(h, &folio_list);
 				INIT_LIST_HEAD(&folio_list);
 				folio = only_alloc_fresh_hugetlb_folio(h, gfp_mask, nid,
-						&node_states[N_MEMORY], NULL);
+						&node_states[N_MEMORY], NULL,
+						NULL);
 			}
 			if (!folio)
 				break;
diff --git a/mm/memfd.c b/mm/memfd.c
index 919c2a53eb96..f1c00600e19a 100644
--- a/mm/memfd.c
+++ b/mm/memfd.c
@@ -93,7 +93,7 @@ struct folio *memfd_alloc_folio(struct file *memfd, pgoff_t idx)
 		folio = alloc_hugetlb_folio_reserve(h,
 						    numa_node_id(),
 						    NULL,
-						    gfp_mask);
+						    gfp_mask, NULL);
 		if (folio) {
 			u32 hash;
 
-- 
MST