Re: [dpdk-users] segmention fault while accessing mbuf

[Alex Kiselev <alex@therouter.net>]

> 1 июня 2020 г., в 19:17, Stephen Hemminger <stephen@networkplumber.org> написал(а):
> 
> On Mon, 01 Jun 2020 15:24:25 +0200
> Alex Kiselev <alex@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.

Could using an incorrect (a very big one) value of mbuf pkt_len and data_len while transmitting cause mbuf corruption and following segmentation fault on rx?