mm: remove PageTransCompound()

Remove the last user of PageTransCompound() in ksm and get rid of
PageTransCompound().

Link: https://lore.kernel.org/20260618113523.3913307-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Xu Xin <xu.xin16@zte.com.cn>
Tested-by: Xu Xin <xu.xin16@zte.com.cn>
Acked-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

2 files changed, 9 insertions, 22 deletions

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 7223f6f4e2b4..7a863572adce 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -879,20 +879,6 @@ FOLIO_FLAG_FALSE(partially_mapped)
 
 #define PG_head_mask ((1UL << PG_head))
 
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-/*
- * PageTransCompound returns true for both transparent huge pages
- * and hugetlbfs pages, so it should only be called when it's known
- * that hugetlbfs pages aren't involved.
- */
-static inline int PageTransCompound(const struct page *page)
-{
-	return PageCompound(page);
-}
-#else
-TESTPAGEFLAG_FALSE(TransCompound, transcompound)
-#endif
-
 #if defined(CONFIG_MEMORY_FAILURE) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
 /*
  * PageHasHWPoisoned indicates that at least one subpage is hwpoisoned in the
diff --git a/mm/ksm.c b/mm/ksm.c
index 7d5b76478f0b..41ab25aa2a82 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -2327,23 +2327,24 @@ static void cmp_and_merge_page(struct page *page, struct ksm_rmap_item *rmap_ite
 	tree_rmap_item =
 		unstable_tree_search_insert(rmap_item, page, &tree_page);
 	if (tree_rmap_item) {
+		struct folio *tree_folio;
 		bool split;
 
 		kfolio = try_to_merge_two_pages(rmap_item, page,
 						tree_rmap_item, tree_page);
+		tree_folio = page_folio(tree_page);
 		/*
-		 * If both pages we tried to merge belong to the same compound
-		 * page, then we actually ended up increasing the reference
-		 * count of the same compound page twice, and split_huge_page
-		 * failed.
+		 * If both pages we tried to merge belong to the same (large)
+		 * folio, then we actually ended up increasing the reference
+		 * count of the same folio twice, and split_huge_page failed.
+		 *
 		 * Here we set a flag if that happened, and we use it later to
-		 * try split_huge_page again. Since we call put_page right
+		 * try split_huge_page again. Since we call folio_put() right
 		 * afterwards, the reference count will be correct and
 		 * split_huge_page should succeed.
 		 */
-		split = PageTransCompound(page)
-			&& compound_head(page) == compound_head(tree_page);
-		put_page(tree_page);
+		split = folio == tree_folio;
+		folio_put(tree_folio);
 		if (kfolio) {
 			/*
 			 * The pages were successfully merged: insert new