[PATCH 2/3] mm/huge_memory: allow split shmem large folio to any lower order

[Zi Yan <ziy@nvidia.com>]

Commit 4d684b5f92ba ("mm: shmem: add large folio support for tmpfs") has
added large folio support to shmem. Remove the restriction in
split_huge_page*().

Signed-off-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
---
 mm/huge_memory.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 3d3ebdc002d5..deb4e72daeb9 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3299,7 +3299,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
 		/* Some pages can be beyond EOF: drop them from page cache */
 		if (tail->index >= end) {
 			if (shmem_mapping(folio->mapping))
-				nr_dropped++;
+				nr_dropped += new_nr;
 			else if (folio_test_clear_dirty(tail))
 				folio_account_cleaned(tail,
 					inode_to_wb(folio->mapping->host));
@@ -3465,12 +3465,6 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
 			return -EINVAL;
 		}
 	} else if (new_order) {
-		/* Split shmem folio to non-zero order not supported */
-		if (shmem_mapping(folio->mapping)) {
-			VM_WARN_ONCE(1,
-				"Cannot split shmem folio to non-0 order");
-			return -EINVAL;
-		}
 		/*
 		 * No split if the file system does not support large folio.
 		 * Note that we might still have THPs in such mappings due to
-- 
2.45.2