Hi there, We're looking at developing some software that uses XSK in zero copy mode, where we either redirect packets to userspace using AF_XDP, or transmit packets straight from the XDP kernel program using XDP_TX. Our program is the same one as described here: https://lore.kernel.org/xdp-newbies/6205E10C-292E-4995-9D10-409649354226@xxxxxxxxxxx/ Recently we've been testing some functionality that transmits packets directly from the data plane / XDP code using XDP_TX. This functionality works on a mellanox MT27710 ConnectX-4 Lx NIC using mlx5_core driver. However, using an Intel NIC with the ice driver, we have some problems. This was tested on the 5.15 kernel and on the newer 6.1 kernel and they both result in the same behaviour. Everything below was seen using the intel NIC with these configs: # ethtool -i ice0 driver: ice version: 6.1.0-0.rc5.el8.elrepo.x86_64 firmware-version: 2.50 0x800077a8 1.2960.0 expansion-rom-version: bus-info: 0000:03:00.0 supports-statistics: yes supports-test: yes supports-eeprom-access: yes supports-register-dump: yes supports-priv-flags: yes # lspci -s 03:00.0 03:00.0 Ethernet controller: Intel Corporation Ethernet Controller E810-XXV for SFP (rev 02) # ethtool -g ice0 Ring parameters for ice0: Pre-set maximums: RX: 8160 RX Mini: n/a RX Jumbo: n/a TX: 8160 Current hardware settings: RX: 4096 RX Mini: n/a RX Jumbo: n/a TX: 4096 # ethtool -l ice0 Channel parameters for ice0: Pre-set maximums: RX: 16 TX: 16 Other: 1 Combined: 16 Current hardware settings: RX: 0 TX: 0 Other: 1 Combined: 4 When redirecting traffic from the data plane into user-space via XSK, everything works as expected. When transmitting packets from the data plane directly out the NIC via XDP_TX, we can see our kernel logs getting hit through the systemd-journal process. It seems to be for every packet sent through XDP_TX, it's generating a kernel warning. An example warning and call trace is: Incorrect XDP memory type (1785255936) usage WARNING: CPU: 7 PID: 0 at net/core/xdp.c:403 __xdp_return+0x33/0x1f0 ... Call Trace: <IRQ> ice_xmit_zc+0x251/0x310 [ice] ice_napi_poll+0x54/0x640 [ice] __napi_poll+0x2b/0x190 net_rx_action+0x2b2/0x310 __do_softirq+0xbe/0x2b6 irq_exit_rcu+0xad/0xd0 common_interrupt+0x82/0xa0 </IRQ> The memory type value seen above changes each error, suggesting that the value is uninitialized or the pointer is corrupted. We have been able to recreate the issue using a program based on the xdpsock sample programs from the kernel tree to validate it’s not specific to our software. We have been testing a simple BPF program that swaps the MAC addresses around and transmits the packet back out of the same NIC. This can be seen here: https://github.com/OpenSource-THG/xdpsock-sample/tree/test_zero_copy_tx on the test_zero_copy_tx branch, which has the very basic BPF program. The issue only occurs when testing the multi FCQ, it seems to work fine on a single FCQ. The issue also happens in copy mode and zero copy mode. The command used was: ./xdpsock_multi --extra-stats --l2fwd --zero-copy --interface ice0 --channels=2 --busy-poll It is my belief that this is a supported scenario, but I’m seeking some guidance to validate my thoughts, and ultimately whether this is a legitimate bug. I hope this gives enough background and information for a reproducible issue. Any feedback is welcome and we look forward to hearing a response. :) Robin Cowley Software Engineer The Hut Group<http://www.thehutgroup.com/> Tel: Email: Robin.Cowley@xxxxxxxxxxxxxxx<mailto:Robin.Cowley@xxxxxxxxxxxxxxx> For the purposes of this email, the "company" means The Hut Group Limited, a company registered in England and Wales (company number 6539496) whose registered office is at Fifth Floor, Voyager House, Chicago Avenue, Manchester Airport, M90 3DQ and/or any of its respective subsidiaries. Confidentiality Notice This e-mail is confidential and intended for the use of the named recipient only. If you are not the intended recipient please notify us by telephone immediately on +44(0)1606 811888 or return it to us by e-mail. Please then delete it from your system and note that any use, dissemination, forwarding, printing or copying is strictly prohibited. Any views or opinions are solely those of the author and do not necessarily represent those of the company. 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