Re: [PATCH net] net: stmmac: fix the crash issue for zero copy XDP_TX action
From: Hariprasad Kelam <hkelam@marvell.com>
Date: 2025-12-17 11:09:14
Also in:
bpf, imx, linux-arm-kernel, lkml
On 2025-12-04 at 12:43:32, Wei Fang (wei.fang@nxp.com) wrote:
quoted hunk ↗ jump to hunk
There is a crash issue when running zero copy XDP_TX action, the crash log is shown below. [ 216.122464] Unable to handle kernel paging request at virtual address fffeffff80000000 [ 216.187524] Internal error: Oops: 0000000096000144 [#1] SMP [ 216.301694] Call trace: [ 216.304130] dcache_clean_poc+0x20/0x38 (P) [ 216.308308] __dma_sync_single_for_device+0x1bc/0x1e0 [ 216.313351] stmmac_xdp_xmit_xdpf+0x354/0x400 [ 216.317701] __stmmac_xdp_run_prog+0x164/0x368 [ 216.322139] stmmac_napi_poll_rxtx+0xba8/0xf00 [ 216.326576] __napi_poll+0x40/0x218 [ 216.408054] Kernel panic - not syncing: Oops: Fatal exception in interrupt For XDP_TX action, the xdp_buff is converted to xdp_frame by xdp_convert_buff_to_frame(). The memory type of the resulting xdp_frame depends on the memory type of the xdp_buff. For page pool based xdp_buff it produces xdp_frame with memory type MEM_TYPE_PAGE_POOL. For zero copy XSK pool based xdp_buff it produces xdp_frame with memory type MEM_TYPE_PAGE_ORDER0. However, stmmac_xdp_xmit_back() does not check the memory type and always uses the page pool type, this leads to invalid mappings and causes the crash. Therefore, check the xdp_buff memory type in stmmac_xdp_xmit_back() to fix this issue. Fixes: bba2556efad6 ("net: stmmac: Enable RX via AF_XDP zero-copy") Signed-off-by: Wei Fang <wei.fang@nxp.com> --- .../net/ethernet/stmicro/stmmac/stmmac_main.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-)diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c index 7b90ecd3a55e..a6664f300e4a 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c@@ -88,6 +88,7 @@ MODULE_PARM_DESC(phyaddr, "Physical device address"); #define STMMAC_XDP_CONSUMED BIT(0) #define STMMAC_XDP_TX BIT(1) #define STMMAC_XDP_REDIRECT BIT(2) +#define STMMAC_XSK_CONSUMED BIT(3) static int flow_ctrl = 0xdead; module_param(flow_ctrl, int, 0644);@@ -4988,6 +4989,7 @@ static int stmmac_xdp_get_tx_queue(struct stmmac_priv *priv, static int stmmac_xdp_xmit_back(struct stmmac_priv *priv, struct xdp_buff *xdp) { + bool zc = !!(xdp->rxq->mem.type == MEM_TYPE_XSK_BUFF_POOL); struct xdp_frame *xdpf = xdp_convert_buff_to_frame(xdp); int cpu = smp_processor_id(); struct netdev_queue *nq;@@ -5004,9 +5006,18 @@ static int stmmac_xdp_xmit_back(struct stmmac_priv *priv, /* Avoids TX time-out as we are sharing with slow path */ txq_trans_cond_update(nq); - res = stmmac_xdp_xmit_xdpf(priv, queue, xdpf, false); - if (res == STMMAC_XDP_TX) + /* For zero copy XDP_TX action, dma_map is true */ + res = stmmac_xdp_xmit_xdpf(priv, queue, xdpf, zc);
Seems stmmac_xdp_xmit_xdpf is using dma_map_single if we pass zc is true.
Ideally in case of zc, driver can use page_pool_get_dma_addr, may be you
need pass zc param as false. Please check
Thanks,
Hariprasad k