RE: mbuf refcnt issue

["Lombardo, Ed" <Ed.Lombardo@netscout.com>]

Hi,
My big issue I have been trying to resolve is when I send packets from a particular pcap file the DPDK mbufs retrieved from rte_eth_rx_burst() after short time showed the mbufs with refcnt not 1.  I then modified our application to set the mbuf to 10 and when the error hit the rte_eth_rx_burst() would then provide mbufs with refcnt set to 10 or 9.  I found testing other pcap files they did not cause any failures.  So, I then analyzed this one pcap file and found that it had "malformed packet (Exception occurred)".  I then removed this one malformed packet from the pcap file and replayed the modified pcap file and no errors occurred.  I think when our application retransmitted this malformed packet it messed up the DPDK mempool and Malicious Driver Detection event occurred.

Thanks,
Ed

-----Original Message-----
From: Stephen Hemminger <stephen@networkplumber.org> 
Sent: Tuesday, April 15, 2025 8:02 PM
To: Lombardo, Ed <Ed.Lombardo@netscout.com>
Cc: Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>; users@dpdk.org
Subject: Re: mbuf refcnt issue

External Email: This message originated outside of NETSCOUT. Do not click links or open attachments unless you recognize the sender and know the content is safe.

On Tue, 15 Apr 2025 13:10:18 +0000
"Lombardo, Ed" <Ed.Lombardo@netscout.com> wrote:

> Hi,
> I enabled more logging, and I see the following ICE Driver Malicious Driver Detection event 6 and 7, in the dpdk_log.txt when failure occurs.
> 
> EAL: Allocated 2112 bytes of per-lcore data with a 64-byte alignment
> ICE_INIT: ice_load_pkg_type(): Active package is: 1.3.35.0, ICE OS 
> Default Package (single VLAN mode)
> ICE_INIT: ice_load_pkg_type(): Active package is: 1.3.35.0, ICE OS 
> Default Package (single VLAN mode)
> MBUF: Registered dynamic field rte_dynfield_timestamp (sz=8, al=8, 
> fl=0x0) -> 96
> MBUF: Registered dynamic flag rte_dynflag_rx_timestamp (fl=0x0) -> 23
> MBUF: Registered dynamic field rte_mbuf_dynfield_udata64 (sz=8, al=8, 
> fl=0x0) -> 104
> ICE_DRIVER: ice_interrupt_handler(): OICR: MDD event
> ICE_DRIVER: ice_interrupt_handler(): Malicious Driver Detection event 
> 7 by TCLAN on TX queue 2 PF# 0
> ICE_DRIVER: ice_interrupt_handler(): Malicious Driver Detection event 
> 6 by TDPU on TX queue 2 PF# 0
> 
> Are malformed packets handled by DPDK, can malformed packets corrupt the mbufs?
> 
> Thanks,
> Ed

I do not know. The malicious driver detection is when application asks to send a packet on a VF that is not for that VF. I.e source MAC or VLAN mismatch.