Thanks for the clarification. I agree: the minimal bugfix belongs in -net for stable backportability, and the conversion to xdp_build_skb_from_zc() belongs in -next.
Please apply the existing v1 bugfix to -net: https://lore.kernel.org/all/[email protected]/ It already has : Reviewed-by: Aleksandr Loktionov <[email protected]> I will drop v2 as a Fixes candidate. In parallel, I will send a separate net-next series (as v1) that replaces i40e_construct_skb_zc() with xdp_build_skb_from_zc(), based on net-next. That patch will not carry a Fixes tag. Thanks, Chenguang 在 2026/7/22 07:15, Jason Xing 写道: > On Fri, Jul 17, 2026 at 9:24 AM Chenguang Zhao <[email protected]> > wrote: >> From: Chenguang Zhao <[email protected]> >> >> When AF_XDP ZC receives a multi-buffer frame and XDP returns XDP_PASS, >> i40e_construct_skb_zc() copied frags incorrectly: memcpy used >> skb_frag_page() (page metadata) and __skb_fill_page_desc_noacc() was >> given a virtual address instead of a struct page *. >> >> Drop the custom helper and use xdp_build_skb_from_zc() instead. On >> failure, free the xdp buff in the caller. Push the Ethernet header >> back before eth_skb_pad()/i40e_process_skb_fields() because >> xdp_build_skb_from_zc() already called eth_type_trans(). >> >> Fixes: 1c9ba9c14658 ("i40e: xsk: add RX multi-buffer support") >> Signed-off-by: Chenguang Zhao <[email protected]> >> --- >> Revised as suggested by Maciej: >> - Replace i40e_construct_skb_zc() with xdp_build_skb_from_zc() > I might have a different opinion on this patch: yes, it actually > belongs to -next material. The process should be like: 1) fix the > issues by v1, 2) refactor it by v2. The reason behind that is the > helper was introduced in 2024 while the home-grown part was in 2023, > which means it doesn't help for stable steam to cherry-pick the patch > in older kernels like 6.6[1]. > > [1]: https://www.kernel.org/ > > Thanks, > Jason > >> v1: >> >> https://lore.kernel.org/all/[email protected]/ >> >> drivers/net/ethernet/intel/i40e/i40e_xsk.c | 73 +++------------------- >> 1 file changed, 8 insertions(+), 65 deletions(-) >> >> diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c >> b/drivers/net/ethernet/intel/i40e/i40e_xsk.c >> index 9f47388eaba5..1319a5c22625 100644 >> --- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c >> +++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c >> @@ -3,6 +3,7 @@ >> >> #include <linux/bpf_trace.h> >> #include <linux/unroll.h> >> +#include <net/xdp.h> >> #include <net/xdp_sock_drv.h> >> #include "i40e_txrx_common.h" >> #include "i40e_xsk.h" >> @@ -277,70 +278,6 @@ bool i40e_alloc_rx_buffers_zc(struct i40e_ring >> *rx_ring, u16 count) >> return count == nb_buffs; >> } >> >> -/** >> - * i40e_construct_skb_zc - Create skbuff from zero-copy Rx buffer >> - * @rx_ring: Rx ring >> - * @xdp: xdp_buff >> - * >> - * This functions allocates a new skb from a zero-copy Rx buffer. >> - * >> - * Returns the skb, or NULL on failure. >> - **/ >> -static struct sk_buff *i40e_construct_skb_zc(struct i40e_ring *rx_ring, >> - struct xdp_buff *xdp) >> -{ >> - unsigned int totalsize = xdp->data_end - xdp->data_meta; >> - unsigned int metasize = xdp->data - xdp->data_meta; >> - struct skb_shared_info *sinfo = NULL; >> - struct sk_buff *skb; >> - u32 nr_frags = 0; >> - >> - if (unlikely(xdp_buff_has_frags(xdp))) { >> - sinfo = xdp_get_shared_info_from_buff(xdp); >> - nr_frags = sinfo->nr_frags; >> - } >> - net_prefetch(xdp->data_meta); >> - >> - /* allocate a skb to store the frags */ >> - skb = napi_alloc_skb(&rx_ring->q_vector->napi, totalsize); >> - if (unlikely(!skb)) >> - goto out; >> - >> - memcpy(__skb_put(skb, totalsize), xdp->data_meta, >> - ALIGN(totalsize, sizeof(long))); >> - >> - if (metasize) { >> - skb_metadata_set(skb, metasize); >> - __skb_pull(skb, metasize); >> - } >> - >> - if (likely(!xdp_buff_has_frags(xdp))) >> - 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]; >> - struct page *page; >> - void *addr; >> - >> - page = dev_alloc_page(); >> - if (!page) { >> - dev_kfree_skb(skb); >> - return NULL; >> - } >> - 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)); >> - } >> - >> -out: >> - xsk_buff_free(xdp); >> - return skb; >> -} >> - >> static void i40e_handle_xdp_result_zc(struct i40e_ring *rx_ring, >> struct xdp_buff *xdp_buff, >> union i40e_rx_desc *rx_desc, >> @@ -372,14 +309,20 @@ static void i40e_handle_xdp_result_zc(struct i40e_ring >> *rx_ring, >> * BIT(I40E_RXD_QW1_ERROR_SHIFT). This is due to that >> * SBP is *not* set in PRT_SBPVSI (default not set). >> */ >> - skb = i40e_construct_skb_zc(rx_ring, xdp_buff); >> + skb = xdp_build_skb_from_zc(xdp_buff); >> if (!skb) { >> + xsk_buff_free(xdp_buff); >> rx_ring->rx_stats.alloc_buff_failed++; >> *rx_packets = 0; >> *rx_bytes = 0; >> return; >> } >> >> + /* xdp_build_skb_from_zc() already ran eth_type_trans(); >> + * restore the header for eth_skb_pad()/process_skb_fields(). >> + */ >> + __skb_push(skb, skb->data - skb_mac_header(skb)); >> + >> if (eth_skb_pad(skb)) { >> *rx_packets = 0; >> *rx_bytes = 0; >> -- >> 2.25.1 >> >>
