[PATCH 3/9] mm: Call free_transhuge_folio() directly from destroy_large_folio()

["Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>]

Indirect calls are expensive, thanks to Spectre.  Convert this one to
a direct call, and pass a folio instead of the head page for type safety.

Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
 include/linux/huge_mm.h | 2 +-
 mm/huge_memory.c        | 5 ++---
 mm/page_alloc.c         | 8 +++++---
 3 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 20284387b841..24aee49a581a 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -144,7 +144,7 @@ unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
 		unsigned long len, unsigned long pgoff, unsigned long flags);
 
 void prep_transhuge_page(struct page *page);
-void free_transhuge_page(struct page *page);
+void free_transhuge_folio(struct folio *folio);
 
 bool can_split_folio(struct folio *folio, int *pextra_pins);
 int split_huge_page_to_list(struct page *page, struct list_head *list);
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 8480728fa220..516fe3c26ef3 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2779,9 +2779,8 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 	return ret;
 }
 
-void free_transhuge_page(struct page *page)
+void free_transhuge_folio(struct folio *folio)
 {
-	struct folio *folio = (struct folio *)page;
 	struct deferred_split *ds_queue = get_deferred_split_queue(folio);
 	unsigned long flags;
 
@@ -2798,7 +2797,7 @@ void free_transhuge_page(struct page *page)
 		}
 		spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
 	}
-	free_compound_page(page);
+	free_compound_page(&folio->page);
 }
 
 void deferred_split_folio(struct folio *folio)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 1f67d4968590..feb2e95cf021 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -287,9 +287,6 @@ const char * const migratetype_names[MIGRATE_TYPES] = {
 static compound_page_dtor * const compound_page_dtors[NR_COMPOUND_DTORS] = {
 	[NULL_COMPOUND_DTOR] = NULL,
 	[COMPOUND_PAGE_DTOR] = free_compound_page,
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-	[TRANSHUGE_PAGE_DTOR] = free_transhuge_page,
-#endif
 };
 
 int min_free_kbytes = 1024;
@@ -624,6 +621,11 @@ void destroy_large_folio(struct folio *folio)
 		return;
 	}
 
+	if (folio_test_transhuge(folio) && dtor == TRANSHUGE_PAGE_DTOR) {
+		free_transhuge_folio(folio);
+		return;
+	}
+
 	VM_BUG_ON_FOLIO(dtor >= NR_COMPOUND_DTORS, folio);
 	compound_page_dtors[dtor](&folio->page);
 }
-- 
2.40.1