Re: [PATCH net] net: add net_iov_init() and use it to initialize ->page_type

[Pavel Begunkov <asml.silence@gmail.com>]

On 4/28/26 03:53, Jakub Kicinski wrote:
> Commit db359fccf212 ("mm: introduce a new page type for page pool in
> page type") added a page_type field to struct net_iov at the same
> offset as struct page::page_type, so that page_pool_set_pp_info() can
> call __SetPageNetpp() uniformly on both pages and net_iovs.
> 
> The page-type API requires the field to hold the UINT_MAX "no type"
> sentinel before a type can be set; for real struct page that invariant
> is established by the page allocator on free. struct net_iov is not
> allocated through the page allocator, so the field is left as zero
> (io_uring zcrx, which uses __GFP_ZERO) or as slab garbage (devmem,
> which uses kvmalloc_objs() without zeroing). When the page pool then
> calls page_pool_set_pp_info() on a freshly-bound niov,
> __SetPageNetpp()'s VM_BUG_ON_PAGE(page->page_type != UINT_MAX) fires
> and the kernel BUGs. Triggered in selftests by io_uring zcrx setup
> through the fbnic queue restart path:

Looks good to me,

Acked-by: Pavel Begunkov <asml.silence@gmail.com>

-- 
Pavel Begunkov