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unregister_netdevice: waiting for vcan0 to become free. Usage count = 2
problem. A debug printk() patch in linux-next-20260508 identified that
there is dev_hold()/dev_put() imbalance in j1939_priv management.
Call trace for vcan0[26] +4 at
__dev_hold include/linux/netdevice.h:4470 [inline]
netdev_hold include/linux/netdevice.h:4513 [inline]
dev_hold include/linux/netdevice.h:4536 [inline]
j1939_priv_create net/can/j1939/main.c:140 [inline]
j1939_netdev_start+0x36b/0xc10 net/can/j1939/main.c:268
j1939_sk_bind+0x853/0xb30 net/can/j1939/socket.c:506
__sys_bind_socket net/socket.c:1948 [inline]
__sys_bind+0x2e9/0x410 net/socket.c:1979
Call trace for vcan0[28] -3 at
__dev_put include/linux/netdevice.h:4456 [inline]
netdev_put include/linux/netdevice.h:4523 [inline]
dev_put include/linux/netdevice.h:4548 [inline]
__j1939_priv_release net/can/j1939/main.c:166 [inline]
kref_put include/linux/kref.h:65 [inline]
j1939_priv_put+0x128/0x270 net/can/j1939/main.c:172
j1939_sk_sock_destruct+0x52/0x90 net/can/j1939/socket.c:388
__sk_destruct+0x8d/0x9d0 net/core/sock.c:2352
rcu_do_batch kernel/rcu/tree.c:2617 [inline]
rcu_core kernel/rcu/tree.c:2869 [inline]
rcu_cpu_kthread+0x99e/0x1470 kernel/rcu/tree.c:2957
smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
This refcount leak in j1939_priv might be caused by a refcount leak in
j1939_{session,ecu} because j1939_{session,ecu} holds a ref on j1939_priv.
For further investigation using upstream kernels, enable netdevice_tracker
in j1939_{priv,session,ecu} management.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://patch.msgid.link/20260728055835.1151785-2-o.rempel@pengutronix.de
Cc: stable@kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
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