slab: Remove folio references in memcg_slab_post_charge()

This allows us to skip the compound_head() call for large kmalloc
objects as the virt_to_page() call will always give us the head page
for the large kmalloc case.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Link: https://patch.msgid.link/20251113000932.1589073-4-willy@infradead.org
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

Author: Matthew Wilcox (Oracle)

mm/slub.c

@@ -2369,33 +2369,34 @@ bool memcg_slab_post_charge(void *p, gfp_t flags)
 {
 	struct slabobj_ext *slab_exts;
 	struct kmem_cache *s;
-	struct folio *folio;
+	struct page *page;
 	struct slab *slab;
 	unsigned long off;
 
-	folio = virt_to_folio(p);
-	if (!folio_test_slab(folio)) {
+	page = virt_to_page(p);
+	if (PageLargeKmalloc(page)) {
+		unsigned int order;
 		int size;
 
-		if (folio_memcg_kmem(folio))
+		if (PageMemcgKmem(page))
 			return true;
 
-		if (__memcg_kmem_charge_page(folio_page(folio, 0), flags,
-					     folio_order(folio)))
+		order = large_kmalloc_order(page);
+		if (__memcg_kmem_charge_page(page, flags, order))
 			return false;
 
 		/*
-		 * This folio has already been accounted in the global stats but
+		 * This page has already been accounted in the global stats but
 		 * not in the memcg stats. So, subtract from the global and use
 		 * the interface which adds to both global and memcg stats.
 		 */
-		size = folio_size(folio);
-		node_stat_mod_folio(folio, NR_SLAB_UNRECLAIMABLE_B, -size);
-		lruvec_stat_mod_folio(folio, NR_SLAB_UNRECLAIMABLE_B, size);
+		size = PAGE_SIZE << order;
+		mod_node_page_state(page_pgdat(page), NR_SLAB_UNRECLAIMABLE_B, -size);
+		mod_lruvec_page_state(page, NR_SLAB_UNRECLAIMABLE_B, size);
 		return true;
 	}
 
-	slab = folio_slab(folio);
+	slab = page_slab(page);
 	s = slab->slab_cache;
 
 	/*