On 5/29/25 20:54, Mina Almasry wrote:
...>>   #endif /* _LINUX_MM_H */

quoted

diff --git a/include/net/netmem.h b/include/net/netmem.h
index f05a8b008d00..9e4ed3530788 100644
--- a/include/net/netmem.h
+++ b/include/net/netmem.h

@@ -53,6 +53,20 @@ NETMEM_DESC_ASSERT_OFFSET(pp_ref_count, pp_ref_count);
   */
  static_assert(sizeof(struct netmem_desc) <= offsetof(struct page, _refcount));

+#ifdef CONFIG_PAGE_POOL
+static inline bool page_pool_page_is_pp(struct page *page)
+{
+       struct netmem_desc *desc = (__force struct netmem_desc *)page;
+

Is it expected that page can be cast to netmem_desc freely? I know it
works now since netmem_desc and page have the same layout, but how is
it going to continue to work when page is shrunk and no longer has
'pp_magic' inside of it? Is that series going to fixup all the places
where casts are done?

It's expected the struct page will have a type field once it's shrunk.

Is it also allowed that we can static cast netmem_desc to page?

Consider creating netmem_desc_page helper like ptdesc_page.

I'm not sure the __force is needed too.

-- 
Pavel Begunkov