[RFC Patch 08/11] mm/huge_memory: restrict @split_at check to non-uniform splits

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

The concept of a uniform split implies that the entire folio is treated
equally, making the specific starting index parameter, @split_at,
irrelevant and unnecessary.

Following previous code cleanups, it is confirmed that @split_at is
indeed unused in the uniform split path.

This commit refactors the validation logic to check the @split_at
parameter only when a non-uniform split is being performed. This
simplifies the uniform split code path and removes a redundant check.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
---
 mm/huge_memory.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index dbb4b86e7d6d..a8ca7c5902f4 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3995,7 +3995,8 @@ static int __folio_split(struct folio *folio, unsigned int new_order,
 	VM_WARN_ON_ONCE_FOLIO(!folio_test_locked(folio), folio);
 	VM_WARN_ON_ONCE_FOLIO(!folio_test_large(folio), folio);
 
-	if (folio != page_folio(split_at) || folio != page_folio(lock_at)) {
+	if ((split_type == SPLIT_TYPE_NON_UNIFORM && folio != page_folio(split_at))
+	    || folio != page_folio(lock_at)) {
 		ret = -EINVAL;
 		goto out;
 	}
-- 
2.34.1