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

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

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.

Link: https://lkml.kernel.org/r/20260122035002.79958-1-lizhe.67@bytedance.com
Signed-off-by: Li Zhe <lizhe.67@bytedance.com>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Acked-by: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>