Bonding shows unknown speed and duplex for one interface

Issue

• Bonding shows unknown speed and duplex for one interface, but they are shown by ethtool commend.

# cat /proc/net/bonding/bond0
Ethernet Channel Bonding Driver: v3.6.0 (September 26, 2009)

Bonding Mode: IEEE 802.3ad Dynamic link aggregation
Transmit Hash Policy: layer2+3 (2)
MII Status: up
MII Polling Interval (ms): 100
Up Delay (ms): 0
Down Delay (ms): 0

802.3ad info
LACP rate: slow
Aggregator selection policy (ad_select): stable
Active Aggregator Info:
        Aggregator ID: 1
        Number of ports: 1
        Actor Key: 33
        Partner Key: 28
        Partner Mac Address: 00:00:00:00:00:1c

Slave Interface: eth0
MII Status: up
Speed: 10000 Mbps
Duplex: full
Link Failure Count: 0
Permanent HW addr: 14:02:ec:84:b4:50
Aggregator ID: 1
Slave queue ID: 0

Slave Interface: eth1
MII Status: up
Speed: Unknown
Duplex: Unknown
Link Failure Count: 0
Permanent HW addr: 14:02:ec:84:b4:51
Aggregator ID: 2
Slave queue ID: 0

There is below message logged in messages file:

kernel: bond0: link status definitely up for interface eth1, 4294967295 Mbps full duplex.