[PATCH v2 02/13] mm: Call free_huge_page() directly

["Matthew Wilcox (Oracle)" <willy@infradead.org>]

Indirect calls are expensive, thanks to Spectre.  Call free_huge_page()
directly if the folio belongs to hugetlb.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/hugetlb.h | 3 ++-
 mm/page_alloc.c         | 8 +++++---
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 0a393bc02f25..5a1dfaffbd80 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -26,6 +26,8 @@ typedef struct { unsigned long pd; } hugepd_t;
 #define __hugepd(x) ((hugepd_t) { (x) })
 #endif
 
+void free_huge_page(struct page *page);
+
 #ifdef CONFIG_HUGETLB_PAGE
 
 #include <linux/mempolicy.h>
@@ -165,7 +167,6 @@ int get_huge_page_for_hwpoison(unsigned long pfn, int flags,
 				bool *migratable_cleared);
 void folio_putback_active_hugetlb(struct folio *folio);
 void move_hugetlb_state(struct folio *old_folio, struct folio *new_folio, int reason);
-void free_huge_page(struct page *page);
 void hugetlb_fix_reserve_counts(struct inode *inode);
 extern struct mutex *hugetlb_fault_mutex_table;
 u32 hugetlb_fault_mutex_hash(struct address_space *mapping, pgoff_t idx);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 8fe9ff917850..548c8016190b 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_HUGETLB_PAGE
-	[HUGETLB_PAGE_DTOR] = free_huge_page,
-#endif
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 	[TRANSHUGE_PAGE_DTOR] = free_transhuge_page,
 #endif
@@ -622,6 +619,11 @@ void destroy_large_folio(struct folio *folio)
 {
 	enum compound_dtor_id dtor = folio->_folio_dtor;
 
+	if (folio_test_hugetlb(folio)) {
+		free_huge_page(&folio->page);
+		return;
+	}
+
 	VM_BUG_ON_FOLIO(dtor >= NR_COMPOUND_DTORS, folio);
 	compound_page_dtors[dtor](&folio->page);
 }
-- 
2.40.1