mlx5 pmd crashing when trying to free mbuf from secondary process when mprq is enabled
https://bugs.dpdk.org/show_bug.cgi?id=990
Bug ID: 990
Summary: mlx5 pmd crashing when trying to free mbuf from
secondary process when mprq is enabled
Product: DPDK
Version: 21.11
Hardware: x86
OS: Linux
Status: UNCONFIRMED
Severity: critical
Priority: Normal
Component: ethdev
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
This issue is always reproducible when any two DPDK applications (primary , secondary) are run on mellanox virtual functions using mlx5_pmd with mprq enabled , segfault occurs whenever the secondary application tries to free a packet received by primary application. Packet size received should be greater than 128Bytes to reproduce this issue.
Run multi process sample application as below on a node with mellanox virtual functions using mlx5_pmd.
First start server application as below
1. /opt/dpdk-mp_server -l 2-3 -n 4 --allow 0000:00:05.0,mprq_en=1,rxqs_min_mprq=1,mprq_log_stride_num=9 --allow 0000:00:06.0,mprq_en=1,rxqs_min_mprq=1
,mprq_log_stride_num=9 --proc-type=primary -- -p 0x3 -n 1
2. Once server is started ,start client application as below
~ # /opt/dpdk-mp_client -l 4 -n 4 --proc-type=auto -- -n 0
3. Then from a different machine connected to the above machine, try to send traffic to the above server/client application using testpmd run as below (note pktsize should be greater than 128Bytes to reproduce this crash, I am using 256Bytes packets).
/opt/dpdk-testpmd -l 2-3 -m 4 --allow 0000:00:04.0,mprq_en=1,rxqs_min_mprq=1,mprq_log_stride_num=9 -- --portmask=0x1 --mbcache=64 --forward-mode=txonly
--eth-peer=0,02:00:17:0A:4B:FB --stats-period=10 --txpkts=256
--tx-ip=10.1.12.253,10.1.12.27 --txq 1 --rxq 1
Once the traffic is received by server application, server will receive packets in mbuf and will send it to client. client will try to free the mbuf during which it is giving segmentation fault.
Rootcause for this issue :
=========================
When server tries to receive the packet, mlx5_pmd is internally calling mprq_buf_to_pkt which will use and attach external buffer to the mbuf (as the packets from testpmd are greater than 128 bytes size).
When external buffers are used, mlx5_pmd will internally sets the callback function, which should free this external buffer to the address of mlx5_mprq_buf_free_cb
i.e mbuf->shinfo->free_cb will be set to address of mlx5_mprq_buf_free_cb in primary application (i.e dpdk-mp_server).
But when this mbuf is given to the secondary application i.e dpdk-mp_client , while freeing this mbuf, secondary application will try to invoke free_cb in mbuf but as this address is not mapped correctly in secondary application, it will give a segmentation fault or could lead to corruption.
[linux-shell]$ nm dpdk_build/examples/dpdk-mp_client |grep -i
"mlx5_mprq_buf_free_cb"00000000008886e0 T mlx5_mprq_buf_free_cb
[linux-shell]$ nm dpdk_build/examples/dpdk-mp_server |grep -i
"mlx5_mprq_buf_free_cb"0000000000888e00 T mlx5_mprq_buf_free_cb
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https://bugs.dpdk.org/show_bug.cgi?id=990
Sahithi Singam ([email protected]) changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution|--- |INVALID--- Comment #2 from Sahithi Singam ([email protected]) --- Marking this bug as invalid as this is already listed as a limitation in mellanox nic guide
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