Hi Stephen, I am looking a the rte_mbuf.h file for rte_pktmbuf_free() and it is not clear to me that it checks if the mbuf refcnt is 1 before decrementing it and allowing the mbuf and segments (if any) to be returned to free pool.
Could my application issue be I have tx threads that transmit packets and does rte_pktmbuf_free(), while one other thread will perform rte_pktmbuf_free() on the same mbuf? I ensured I bump the mbuf refcnt to 2 before other threads can process the same mbuf. Thanks, Ed -----Original Message----- From: Stephen Hemminger <step...@networkplumber.org> Sent: Tuesday, April 8, 2025 11:54 PM To: Lombardo, Ed <ed.lomba...@netscout.com> Cc: Dmitry Kozlyuk <dmitry.kozl...@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, 8 Apr 2025 22:33:56 +0000 "Lombardo, Ed" <ed.lomba...@netscout.com> wrote: > Hi Dmitry, > I added mbuf refcnt check at the point where we get the packets from DPDK > rte_eth_rx_burst() and I am finding many mbufs refcnt set to 2 when I expect > them to be 1. This is more evidence that something has gone wrong within > DPDK and the mempool management, perhaps, and I don't know how my setup went > into this state. I changed the traffic type from Telnet to Enterprise > traffic and rte_eth_tx_burst() no longer accepts mbufs. Not likely a DPDK bug. More likely you are having application problems. Have you tried enabling things like RTE_LIBRTE_MBUF_DEBUG and RTE_LIBRTE_MEMPOOL_DEBUG and RTE_ENABLE_ASSERT? Also using a current version of DPDK, address sanitizer, and latest GCC or CLANG can uncover issues with use after free.
