mm: call free_huge_page() directly

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

Link: https://lkml.kernel.org/r/20230816151201.3655946-3-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Yanteng Si <siyanteng@loongson.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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);

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
@@ -612,6 +609,11 @@ 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);
 }