Merge tag 'slab-for-6.18-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab

Pull slab fix from Vlastimil Babka:

 - Fix mempool poisoning order>0 pages with CONFIG_HIGHMEM (Vlastimil Babka)

* tag 'slab-for-6.18-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab:
  mm/mempool: fix poisoning order>0 pages with HIGHMEM

Author: torvalds

mm/mempool.c

@@ -68,10 +68,20 @@ static void check_element(mempool_t *pool, void *element)
 	} else if (pool->free == mempool_free_pages) {
 		/* Mempools backed by page allocator */
 		int order = (int)(long)pool->pool_data;
-		void *addr = kmap_local_page((struct page *)element);
 
-		__check_element(pool, addr, 1UL << (PAGE_SHIFT + order));
-		kunmap_local(addr);
+#ifdef CONFIG_HIGHMEM
+		for (int i = 0; i < (1 << order); i++) {
+			struct page *page = (struct page *)element;
+			void *addr = kmap_local_page(page + i);
+
+			__check_element(pool, addr, PAGE_SIZE);
+			kunmap_local(addr);
+		}
+#else
+		void *addr = page_address((struct page *)element);
+
+		__check_element(pool, addr, PAGE_SIZE << order);
+#endif
 	}
 }
 
@@ -97,10 +107,20 @@ static void poison_element(mempool_t *pool, void *element)
 	} else if (pool->alloc == mempool_alloc_pages) {
 		/* Mempools backed by page allocator */
 		int order = (int)(long)pool->pool_data;
-		void *addr = kmap_local_page((struct page *)element);
 
-		__poison_element(addr, 1UL << (PAGE_SHIFT + order));
-		kunmap_local(addr);
+#ifdef CONFIG_HIGHMEM
+		for (int i = 0; i < (1 << order); i++) {
+			struct page *page = (struct page *)element;
+			void *addr = kmap_local_page(page + i);
+
+			__poison_element(addr, PAGE_SIZE);
+			kunmap_local(addr);
+		}
+#else
+		void *addr = page_address((struct page *)element);
+
+		__poison_element(addr, PAGE_SIZE << order);
+#endif
 	}
 }
 #else /* CONFIG_SLUB_DEBUG_ON */