On Tue, Jul 14, 2026 at 10:51:12AM +0800, Chenguang Zhao wrote:
> From: Chenguang Zhao <[email protected]>
>
> When AF_XDP ZC receives a multi-buffer frame and the XDP program
> returns XDP_PASS, i40e_construct_skb_zc() copies frags into a new
> skb. The copy used skb_frag_page() as the memcpy source (page
> metadata instead of packet data) and passed a virtual address to
> __skb_fill_page_desc_noacc(), which expects a struct page *.
>
> Use skb_frag_address() for the copy, attach frags with
> skb_add_rx_frag() so len/data_len/truesize are updated, and on
> dev_alloc_page() failure free the skb via the shared out path so
> xsk_buff_free() still runs and previously attached pages are
> released by kfree_skb.
>
> Fixes: 1c9ba9c14658 ("i40e: xsk: add RX multi-buffer support")
> Signed-off-by: Chenguang Zhao <[email protected]>
> ---
> - Fix memcpy source: use skb_frag_address() instead of skb_frag_page(),
> which was copying page metadata rather than packet data.
>
> - Fix frag attachment: pass the allocated struct page * to the skb frag
> helper instead of the page virtual address.
>
> - Use skb_add_rx_frag() so skb->len, data_len and truesize are updated
> when attaching copied frags.
>
> - On mid-loop dev_alloc_page() failure, go through the shared out path
> so previously attached pages are released via kfree_skb and
> xsk_buff_free() is still called.
Hi!
I assume this is a fix, so you should include your target tree in patch
subject (net) plus Fixes: tag.
However, could you take a look if we could use xdp_build_skb_from_zc() and
wipe out i40e_construct_skb_zc() altogether?
>
> drivers/net/ethernet/intel/i40e/i40e_xsk.c | 13 +++++--------
> 1 file changed, 5 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c
> b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
> index 9f47388eaba5..a4247710c85b 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
> @@ -318,22 +318,19 @@ static struct sk_buff *i40e_construct_skb_zc(struct
> i40e_ring *rx_ring,
> goto out;
>
> for (int i = 0; i < nr_frags; i++) {
> - struct skb_shared_info *skinfo = skb_shinfo(skb);
> skb_frag_t *frag = &sinfo->frags[i];
> + unsigned int frag_size = skb_frag_size(frag);
> struct page *page;
> - void *addr;
>
> page = dev_alloc_page();
> if (!page) {
> dev_kfree_skb(skb);
> - return NULL;
> + skb = NULL;
> + goto out;
> }
> - addr = page_to_virt(page);
>
> - memcpy(addr, skb_frag_page(frag), skb_frag_size(frag));
> -
> - __skb_fill_page_desc_noacc(skinfo, skinfo->nr_frags++,
> - addr, 0, skb_frag_size(frag));
> + memcpy(page_to_virt(page), skb_frag_address(frag), frag_size);
> + skb_add_rx_frag(skb, i, page, 0, frag_size, PAGE_SIZE);
> }
>
> out:
> --
> 2.25.1
>
>
