To reproduce:

"""
$ dpdk-testpmd -n 4 -a
0000:08:00.0,dv_xmeta_en=1,rxqs_min_mprq=4,mprq_en=1,mprq_max_memcpy_len=1606,mprq_log_stride_size=7,mprq_log_stride_num=10,txq_inline_max=472,txq_inline_mpw=401,txqs_min_inline=12,hp_buf_log_sz=17,representor=[0,1]
--iova-mode="va" -- --mbcache=512 -i --nb-cores=8 --rxq=8 --txq=8 --txd=2048
--rxd=2048 --burst=64 --enable-scatter --tx-offloads=0x8000
[..]
Configuring Port 0 (socket 0)
mlx5_pci: Port 0 Rx queue 0 size of a stride for Multi-Packet RQ is adjusted to
match the mbuf size (1646)
[..]
Port 0: 10:70:FD:D9:0F:C8
Configuring Port 1 (socket 0)
mlx5_pci: Port 1 Rx queue 0 size of a stride for Multi-Packet RQ is adjusted to
match the mbuf size (1646)
[..]
Port 1: A6:68:00:C8:79:FD
Configuring Port 2 (socket 0)
mlx5_pci: Port 2 Rx queue 0 size of a stride for Multi-Packet RQ is adjusted to
match the mbuf size (1646)
[..]
Port 2: C6:8F:13:5B:6B:F0
Checking link statuses...
Done
testpmd> port stop all
Stopping ports...
Checking link statuses...
Done
testpmd> port config all max-pkt-len 4096
testpmd> port start all
Configuring Port 0 (socket 0)
mlx5_pci: Port 0 Rx queue 0 size of a stride for Multi-Packet RQ is adjusted to
match the mbuf size (4224)
[..]
Port 0: 10:70:FD:D9:0F:C8
Configuring Port 1 (socket 0)
mlx5_pci: Port 1 Rx queue 0 size of a stride for Multi-Packet RQ is adjusted to
match the mbuf size (4224)
[..]
Port 1: A6:68:00:C8:79:FD
Configuring Port 2 (socket 0)
mlx5_pci: Port 2 Rx queue 0 size of a stride for Multi-Packet RQ is adjusted to
match the mbuf size (4224)
[..]
mlx5_pci: port 2 failed to allocate a mempool for Multi-Packet RQ, count=1280,
size=526016
mlx5_pci: port 2 Rx queue allocation failed: Cannot allocate memory
Fail to start port 2
Please stop the ports first
"""

OS: Ubuntu 20.04
DPDK: 20.11.9-rc1
Device: ConnectX-6 DX
MLNX_OFED: 23.04-1.1.3.0
Firmware: 22.37.1014