[PATCH] hugetlb: increase hugepage reservations when using node-specific "hugepages=" cmdline

["Li Zhe" <lizhe.67@bytedance.com>]

Commit 3dfd02c90037 ("hugetlb: increase number of reserving hugepages
via cmdline") raised the number of hugepages that can be reserved
through the boot-time "hugepages=" parameter for the non-node-specific
case, but left the node-specific form of the same parameter unchanged.

This patch extends the same optimization to node-specific reservations.
When HugeTLB vmemmap optimization (HVO) is enabled and a node cannot
satisfy the requested hugepages, the code first releases ordinary
struct-page memory of hugepages obtained from the buddy allocator,
allowing their struct-page memory to be reclaimed and reused for
additional hugepage reservations on that node.

This is particularly beneficial for configurations that require
identical, large per-node hugepage reservations. On a four-node, 384 GB
x86 VM, the patch raises the attainable 2 MiB hugepage reservation from
under 374 GB to more than 379 GB.

Signed-off-by: Li Zhe <lizhe.67@bytedance.com>
---
 mm/hugetlb.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index a1832da0f623..008315616c3b 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3425,6 +3425,13 @@ static void __init hugetlb_hstate_alloc_pages_onenode(struct hstate *h, int nid)
 
 			folio = only_alloc_fresh_hugetlb_folio(h, gfp_mask, nid,
 					&node_states[N_MEMORY], 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);
+			}
 			if (!folio)
 				break;
 			list_add(&folio->lru, &folio_list);
-- 
2.20.1