diff --git a/include/net/page_pool.h b/include/net/page_pool.h
index 34bf531ffc8d6a05ac4d4cdf90fc54b2855d9580..ddfa0b3286777632b4891560b74f7e671434aeca 100644
--- a/include/net/page_pool.h
+++ b/include/net/page_pool.h
@@ -277,6 +277,16 @@ void page_pool_put_defragged_page(struct page_pool *pool, struct page *page,
 				  unsigned int dma_sync_size,
 				  bool allow_direct);
 
+/* pp_frag_count represents the number of writers who can update the page
+ * either by updating skb->data or via DMA mappings for the device.
+ * We can't rely on the page refcnt for that as we don't know who might be
+ * holding page references and we can't reliably destroy or sync DMA mappings
+ * of the fragments.
+ *
+ * When pp_frag_count reaches 0 we can either recycle the page if the page
+ * refcnt is 1 or return it back to the memory allocator and destroy any
+ * mappings we have.
+ */
 static inline void page_pool_fragment_page(struct page *page, long nr)
 {
 	atomic_long_set(&page->pp_frag_count, nr);