While configuring a vxlan tunnel in a system with a i40e NIC driver, I
observe the following deadlock:
WARNING: possible recursive locking detected
6.16.0-rc2.net-next-6.16_92d87230d899+ #13 Tainted: G E
--------------------------------------------
kworker/u256:4/1125 is trying to acquire lock:
ffff88921ab9c8c8 (&utn->lock){+.+.}-{4:4}, at: i40e_udp_tunnel_set_port (/home/pabeni/net-next/include/net/udp_tunnel.h:343 /home/pabeni/net-next/drivers/net/ethernet/intel/i40e/i40e_main.c:13013) i40e
but task is already holding lock:
ffff88921ab9c8c8 (&utn->lock){+.+.}-{4:4}, at: udp_tunnel_nic_device_sync_work (/home/pabeni/net-next/net/ipv4/udp_tunnel_nic.c:739) udp_tunnel
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&utn->lock);
lock(&utn->lock);
*** DEADLOCK ***
May be due to missing lock nesting notation
4 locks held by kworker/u256:4/1125:
#0: ffff8892910ca158 ((wq_completion)udp_tunnel_nic){+.+.}-{0:0}, at: process_one_work (/home/pabeni/net-next/kernel/workqueue.c:3213)
#1: ffffc900244efd30 ((work_completion)(&utn->work)){+.+.}-{0:0}, at: process_one_work (/home/pabeni/net-next/kernel/workqueue.c:3214)
#2: ffffffff9a14e290 (rtnl_mutex){+.+.}-{4:4}, at: udp_tunnel_nic_device_sync_work (/home/pabeni/net-next/net/ipv4/udp_tunnel_nic.c:737) udp_tunnel
#3: ffff88921ab9c8c8 (&utn->lock){+.+.}-{4:4}, at: udp_tunnel_nic_device_sync_work (/home/pabeni/net-next/net/ipv4/udp_tunnel_nic.c:739) udp_tunnel
stack backtrace:
Hardware name: Dell Inc. PowerEdge R7525/0YHMCJ, BIOS 2.2.5 04/08/2021
i
Call Trace:
<TASK>
dump_stack_lvl (/home/pabeni/net-next/lib/dump_stack.c:123)
print_deadlock_bug (/home/pabeni/net-next/kernel/locking/lockdep.c:3047)
validate_chain (/home/pabeni/net-next/kernel/locking/lockdep.c:3901)
__lock_acquire (/home/pabeni/net-next/kernel/locking/lockdep.c:5240)
lock_acquire.part.0 (/home/pabeni/net-next/kernel/locking/lockdep.c:473 /home/pabeni/net-next/kernel/locking/lockdep.c:5873)
__mutex_lock (/home/pabeni/net-next/kernel/locking/mutex.c:604 /home/pabeni/net-next/kernel/locking/mutex.c:747)
i40e_udp_tunnel_set_port (/home/pabeni/net-next/include/net/udp_tunnel.h:343 /home/pabeni/net-next/drivers/net/ethernet/intel/i40e/i40e_main.c:13013) i40e
udp_tunnel_nic_device_sync_by_port (/home/pabeni/net-next/net/ipv4/udp_tunnel_nic.c:230 /home/pabeni/net-next/net/ipv4/udp_tunnel_nic.c:249) udp_tunnel
__udp_tunnel_nic_device_sync.part.0 (/home/pabeni/net-next/net/ipv4/udp_tunnel_nic.c:292) udp_tunnel
udp_tunnel_nic_device_sync_work (/home/pabeni/net-next/net/ipv4/udp_tunnel_nic.c:742) udp_tunnel
process_one_work (/home/pabeni/net-next/kernel/workqueue.c:3243)
worker_thread (/home/pabeni/net-next/kernel/workqueue.c:3315 /home/pabeni/net-next/kernel/workqueue.c:3402)
kthread (/home/pabeni/net-next/kernel/kthread.c:464)
AFAICS all the existing callsites of udp_tunnel_nic_set_port_priv() are
already under the utn lock scope, avoid (re-)acquiring it in such a
function.
Fixes: 1ead750109 ("udp_tunnel: remove rtnl_lock dependency")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/95a827621ec78c12d1564ec3209e549774f9657d.1750675978.git.pabeni@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
c9e78afa68