[dpdk-users] segmention fault while accessing mbuf

[Stephen Hemminger]

On Mon, 01 Jun 2020 15:24:25 +0200
Alex Kiselev <alex at therouter.net> wrote:

> Hello,
> 
> I've got a segmentation fault error in my data plane path.
> I am pretty sure the code where the segfault happened is ok,
> so my guess is that I somehow received a corrupted mbuf.
> How could I troubleshoot this? Is there any way?
> Is it possible that other threads of the application
> corrupted that mbuf?
> 
> I would really appriciate any advice.
> Thanks.
> 
> DPDK 18.11.3
> NIC: 82599ES
> 
> Code:
> 
> nb_rx = rte_eth_rx_burst(port_id, queue_id, pkts_burst,
> 		  MAX_PKT_BURST);
> 
> ...
> 
> for (i=0; i < vec_size; i++) {
> 	rte_prefetch0(rte_pktmbuf_mtod(m_v[i], void *));
> 
> for (i=0; i < vec_size; i++) {
> 	m = m_v[i];
> 	eth_hdr = rte_pktmbuf_mtod(m, struct ether_hdr *);
> 	eth_type = rte_be_to_cpu_16(eth_hdr->ether_type);               <--- 
> Segmentation fault
> 	...
> 
> #0  rte_arch_bswap16 (_x=<error reading variable: Cannot access memory 
> at address 0x4d80000000053010>)

Build with as many of the debug options turned on in the DPDK config,
and build with EXTRA_CFLAGS of -g.