[RFC Patch 11/11] mm/huge_memory: simplify split_huge_page() by calling __folio_split() directly

[Wei Yang <richard.weiyang@gmail.com>]

The current function call chain for splitting huge pages is overly
verbose:

split_huge_page() -> split_huge_page_to_list_to_order() ->
__split_huge_page_to_list_to_order() -> __folio_split()

Since __split_huge_page_to_list_to_order() is merely a wrapper for
__folio_split(), and it is only used by
split_huge_page_to_list_to_order() (which is, in turn, only used by
split_huge_page()), the intermediate functions are redundant.

This commit refactors split_huge_page() to call __folio_split()
directly. This removes the unnecessary middle layers
(split_huge_page_to_list_to_order() and
__split_huge_page_to_list_to_order()), simplifying the splitting
interface.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
---
 include/linux/huge_mm.h | 20 +-------------------
 mm/huge_memory.c        |  5 ++---
 2 files changed, 3 insertions(+), 22 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 95a68c19e177..a977e032385c 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -369,8 +369,6 @@ enum split_type {
 	SPLIT_TYPE_NON_UNIFORM,
 };
 
-int __split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
-		unsigned int new_order);
 int folio_split_unmapped(struct folio *folio, unsigned int new_order);
 unsigned int min_order_for_split(struct folio *folio);
 int split_folio_to_list(struct folio *folio, struct list_head *list);
@@ -380,12 +378,6 @@ int folio_split_uniform(struct folio *folio, unsigned int new_order, struct list
 int folio_split(struct folio *folio, unsigned int new_order, struct page *page,
 		struct list_head *list);
 
-static inline int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
-		unsigned int new_order)
-{
-	return __split_huge_page_to_list_to_order(page, list, new_order);
-}
-
 static inline int split_folio_to_order(struct folio *folio, int new_order)
 {
 	return folio_split_uniform(folio, new_order, NULL);
@@ -412,10 +404,7 @@ static inline int try_folio_split_to_order(struct folio *folio,
 		return split_folio_to_order(folio, new_order);
 	return folio_split(folio, new_order, page, NULL);
 }
-static inline int split_huge_page(struct page *page)
-{
-	return split_huge_page_to_list_to_order(page, NULL, 0);
-}
+int split_huge_page(struct page *page);
 void deferred_split_folio(struct folio *folio, bool partially_mapped);
 #ifdef CONFIG_MEMCG
 void reparent_deferred_split_queue(struct mem_cgroup *memcg);
@@ -614,13 +603,6 @@ can_split_folio(struct folio *folio, int caller_pins, int *pextra_pins)
 {
 	return false;
 }
-static inline int
-split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
-		unsigned int new_order)
-{
-	VM_WARN_ON_ONCE_PAGE(1, page);
-	return -EINVAL;
-}
 static inline int split_huge_page(struct page *page)
 {
 	VM_WARN_ON_ONCE_PAGE(1, page);
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index cedecfc1a40c..ded17d0fa695 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -4190,12 +4190,11 @@ int folio_split_unmapped(struct folio *folio, unsigned int new_order)
 	return ret;
 }
 
-int __split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
-				     unsigned int new_order)
+int split_huge_page(struct page *page)
 {
 	struct folio *folio = page_folio(page);
 
-	return __folio_split(folio, new_order, &folio->page, page, list,
+	return __folio_split(folio, 0, &folio->page, page, NULL,
 			     SPLIT_TYPE_UNIFORM);
 }
 
-- 
2.34.1