============================================ WARNING: possible recursive locking detected 6.15.0-rc7-syzkaller-00082-g5cdb2c77c4c3 #0 Not tainted -------------------------------------------- kworker/u8:30/8039 is trying to acquire lock: ffff8880582da218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#7){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff8880582da218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#7){+.-.}-{3:3}, at: __dev_xmit_skb net/core/dev.c:4052 [inline] ffff8880582da218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#7){+.-.}-{3:3}, at: __dev_queue_xmit+0x2228/0x3a70 net/core/dev.c:4595 but task is already holding lock: ffff8880582da218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#7){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff8880582da218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#7){+.-.}-{3:3}, at: __dev_xmit_skb net/core/dev.c:4052 [inline] ffff8880582da218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#7){+.-.}-{3:3}, at: __dev_queue_xmit+0x2228/0x3a70 net/core/dev.c:4595 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#7); lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#7); *** DEADLOCK *** May be due to missing lock nesting notation 12 locks held by kworker/u8:30/8039: #0: ffff88805c665148 ((wq_completion)wg-kex-wg0#7){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline] #0: ffff88805c665148 ((wq_completion)wg-kex-wg0#7){+.+.}-{0:0}, at: process_scheduled_works+0x9b1/0x17a0 kernel/workqueue.c:3319 #1: ffffc90003a0fc60 ((work_completion)(&peer->transmit_handshake_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline] #1: ffffc90003a0fc60 ((work_completion)(&peer->transmit_handshake_work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ec/0x17a0 kernel/workqueue.c:3319 #2: ffff888079f03ce8 (&peer->endpoint_lock){++-.}-{3:3}, at: wg_socket_send_skb_to_peer+0x54/0x1d0 drivers/net/wireguard/socket.c:173 #3: ffffffff8df3df40 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #3: ffffffff8df3df40 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:892 [inline] #3: ffffffff8df3df40 (rcu_read_lock_bh){....}-{1:3}, at: send6+0x220/0x8d0 drivers/net/wireguard/socket.c:118 #4: ffffffff8df3dee0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #4: ffffffff8df3dee0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #4: ffffffff8df3dee0 (rcu_read_lock){....}-{1:3}, at: ip6_finish_output2+0x701/0x16a0 net/ipv6/ip6_output.c:126 #5: ffffffff8df3df40 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #5: ffffffff8df3df40 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:892 [inline] #5: ffffffff8df3df40 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x27e/0x3a70 net/core/dev.c:4554 #6: ffff8880582da218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#7){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline] #6: ffff8880582da218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#7){+.-.}-{3:3}, at: __dev_xmit_skb net/core/dev.c:4052 [inline] #6: ffff8880582da218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#7){+.-.}-{3:3}, at: __dev_queue_xmit+0x2228/0x3a70 net/core/dev.c:4595 #7: ffffffff8df3dee0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #7: ffffffff8df3dee0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #7: ffffffff8df3dee0 (rcu_read_lock){....}-{1:3}, at: icmp6_send+0x1e9/0x1940 net/ipv6/icmp.c:477 #8: ffff88814d3581d8 (k-slock-AF_INET6){+.-.}-{3:3}, at: spin_trylock include/linux/spinlock.h:361 [inline] #8: ffff88814d3581d8 (k-slock-AF_INET6){+.-.}-{3:3}, at: icmpv6_xmit_lock net/ipv6/icmp.c:108 [inline] #8: ffff88814d3581d8 (k-slock-AF_INET6){+.-.}-{3:3}, at: icmp6_send+0xc5c/0x1940 net/ipv6/icmp.c:554 #9: ffffffff8df3dee0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #9: ffffffff8df3dee0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #9: ffffffff8df3dee0 (rcu_read_lock){....}-{1:3}, at: ip6_send_skb+0x10f/0x390 net/ipv6/ip6_output.c:1980 #10: ffffffff8df3dee0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #10: ffffffff8df3dee0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #10: ffffffff8df3dee0 (rcu_read_lock){....}-{1:3}, at: ip6_finish_output2+0x701/0x16a0 net/ipv6/ip6_output.c:126 #11: ffffffff8df3df40 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #11: ffffffff8df3df40 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:892 [inline] #11: ffffffff8df3df40 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x27e/0x3a70 net/core/dev.c:4554 stack backtrace: CPU: 0 UID: 0 PID: 8039 Comm: kworker/u8:30 Not tainted 6.15.0-rc7-syzkaller-00082-g5cdb2c77c4c3 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Workqueue: wg-kex-wg0 wg_packet_handshake_send_worker Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_deadlock_bug+0x28b/0x2a0 kernel/locking/lockdep.c:3042 check_deadlock kernel/locking/lockdep.c:3094 [inline] validate_chain+0x1a3f/0x2140 kernel/locking/lockdep.c:3896 __lock_acquire+0xaac/0xd20 kernel/locking/lockdep.c:5235 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] __dev_xmit_skb net/core/dev.c:4052 [inline] __dev_queue_xmit+0x2228/0x3a70 net/core/dev.c:4595 neigh_output include/net/neighbour.h:539 [inline] ip6_finish_output2+0x11fb/0x16a0 net/ipv6/ip6_output.c:141 __ip6_finish_output net/ipv6/ip6_output.c:-1 [inline] ip6_finish_output+0x234/0x7d0 net/ipv6/ip6_output.c:226 ip6_send_skb+0x1d5/0x390 net/ipv6/ip6_output.c:1981 icmp6_send+0x12c6/0x1940 net/ipv6/icmp.c:632 __icmpv6_send include/linux/icmpv6.h:28 [inline] icmpv6_send include/linux/icmpv6.h:49 [inline] ip6_link_failure+0x3b/0x4c0 net/ipv6/route.c:2834 dst_link_failure include/net/dst.h:429 [inline] ip6_tnl_xmit+0xe15/0x2b00 net/ipv6/ip6_tunnel.c:1285 ipxip6_tnl_xmit net/ipv6/ip6_tunnel.c:1401 [inline] ip6_tnl_start_xmit+0xc1d/0x1150 net/ipv6/ip6_tunnel.c:1449 __netdev_start_xmit include/linux/netdevice.h:5204 [inline] netdev_start_xmit include/linux/netdevice.h:5213 [inline] xmit_one net/core/dev.c:3776 [inline] dev_hard_start_xmit+0x2ff/0x880 net/core/dev.c:3792 sch_direct_xmit+0x241/0x4b0 net/sched/sch_generic.c:343 __dev_xmit_skb net/core/dev.c:4068 [inline] __dev_queue_xmit+0x1992/0x3a70 net/core/dev.c:4595 neigh_output include/net/neighbour.h:539 [inline] ip6_finish_output2+0x11fb/0x16a0 net/ipv6/ip6_output.c:141 __ip6_finish_output net/ipv6/ip6_output.c:-1 [inline] ip6_finish_output+0x234/0x7d0 net/ipv6/ip6_output.c:226 ip6tunnel_xmit include/net/ip6_tunnel.h:161 [inline] udp_tunnel6_xmit_skb+0x5da/0xa60 net/ipv6/ip6_udp_tunnel.c:111 send6+0x5aa/0x8d0 drivers/net/wireguard/socket.c:152 wg_socket_send_skb_to_peer+0x111/0x1d0 drivers/net/wireguard/socket.c:178 wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline] wg_packet_handshake_send_worker+0x1db/0x320 drivers/net/wireguard/send.c:51 process_one_work kernel/workqueue.c:3238 [inline] process_scheduled_works+0xadb/0x17a0 kernel/workqueue.c:3319 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400 kthread+0x70e/0x8a0 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245