Hi Brenden, I've discovered a bug with XDP_TX recycling of pages in the mlx4 driver.
If I increase the number of RX and TX queues/channels via ethtool cmd: ethtool -L mlx4p1 rx 10 tx 10 Then when running the xdp2 program, which does XDP_TX, the kernel will crash with page errors, because the page refcnt goes to zero or even minus. I've noticed pages delivered to mlx4_en_rx_recycle() can have a page refcnt of zero, which is wrong, they should always have 1 (for XDP). Debugging it further, I find that this can happen when mlx4_en_rx_recycle() is called from mlx4_en_recycle_tx_desc(). This is the TX cleanup function, associated with TX ring queues used for XDP_TX only. No others than the XDP_TX action should be able to place packets into these TX rings which call mlx4_en_recycle_tx_desc(). Do you have any idea of what could be going wrong in this case? -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat Author of http://www.iptv-analyzer.org LinkedIn: http://www.linkedin.com/in/brouer
