[PATCH v2 12/22] slab: Remove folio references from kvfree_rcu_cb()

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

As with memcg_slab_post_charge(), we save a call to compound_head()
for large kmallocs.  This has a slight change of behaviour in that
non-vmalloc, non-slab, non-kmalloc pointers will now cause a NULL
pointer dereference rather than a warning.  We could add that back if
really needed.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 mm/slub.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 68a013411ff7..547ef6ef4373 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -6252,7 +6252,7 @@ static void free_large_kmalloc(struct page *page, void *object)
 void kvfree_rcu_cb(struct rcu_head *head)
 {
 	void *obj = head;
-	struct folio *folio;
+	struct page *page;
 	struct slab *slab;
 	struct kmem_cache *s;
 	void *slab_addr;
@@ -6263,20 +6263,20 @@ void kvfree_rcu_cb(struct rcu_head *head)
 		return;
 	}
 
-	folio = virt_to_folio(obj);
-	if (!folio_test_slab(folio)) {
+	page = virt_to_page(obj);
+	if (PageLargeKmalloc(page)) {
 		/*
 		 * rcu_head offset can be only less than page size so no need to
-		 * consider folio order
+		 * consider allocation order
 		 */
 		obj = (void *) PAGE_ALIGN_DOWN((unsigned long)obj);
-		free_large_kmalloc(&folio->page, obj);
+		free_large_kmalloc(page, obj);
 		return;
 	}
 
-	slab = folio_slab(folio);
+	slab = page_slab(page);
 	s = slab->slab_cache;
-	slab_addr = folio_address(folio);
+	slab_addr = slab_address(slab);
 
 	if (is_kfence_address(obj)) {
 		obj = kfence_object_start(obj);
-- 
2.47.2