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From: Alex Kiselev <alex@therouter.net>
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To: Stephen Hemminger <stephen@networkplumber.org>
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Subject: Re: [dpdk-users] segmention fault while accessing mbuf
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> 1 =D0=B8=D1=8E=D0=BD=D1=8F 2020 =D0=B3., =D0=B2 19:17, Stephen Hemminger <=
stephen@networkplumber.org> =D0=BD=D0=B0=D0=BF=D0=B8=D1=81=D0=B0=D0=BB(=D0=B0=
):
>=20
> On Mon, 01 Jun 2020 15:24:25 +0200
> Alex Kiselev <alex@therouter.net> wrote:
>=20
>> Hello,
>>=20
>> 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?
>>=20
>> I would really appriciate any advice.
>> Thanks.
>>=20
>> DPDK 18.11.3
>> NIC: 82599ES
>>=20
>> Code:
>>=20
>> nb_rx =3D rte_eth_rx_burst(port_id, queue_id, pkts_burst,
>>          MAX_PKT_BURST);
>>=20
>> ...
>>=20
>> for (i=3D0; i < vec_size; i++) {
>>    rte_prefetch0(rte_pktmbuf_mtod(m_v[i], void *));
>>=20
>> for (i=3D0; i < vec_size; i++) {
>>    m =3D m_v[i];
>>    eth_hdr =3D rte_pktmbuf_mtod(m, struct ether_hdr *);
>>    eth_type =3D rte_be_to_cpu_16(eth_hdr->ether_type);               <---=
=20
>> Segmentation fault
>>    ...
>>=20
>> #0  rte_arch_bswap16 (_x=3D<error reading variable: Cannot access memory=20=

>> at address 0x4d80000000053010>)
>=20
> 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 o=
n rx?=