============================================ WARNING: possible recursive locking detected 6.3.0-rc7-syzkaller-g6a8f57ae2eb0 #0 Not tainted -------------------------------------------- syz-executor.0/5540 is trying to acquire lock: ffff8880726258d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] ffff8880726258d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4335 [inline] ffff8880726258d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __dev_queue_xmit+0x17f4/0x3bb0 net/core/dev.c:4243 but task is already holding lock: ffff88802ae2f4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] ffff88802ae2f4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4335 [inline] ffff88802ae2f4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x1c4/0x5f0 net/sched/sch_generic.c:340 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(_xmit_ETHER#2); lock(_xmit_ETHER#2); *** DEADLOCK *** May be due to missing lock nesting notation 6 locks held by syz-executor.0/5540: #0: ffffffff8cf25400 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x40 include/linux/rcupdate.h:327 #1: ffffffff8cf25400 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x40 include/linux/rcupdate.h:327 #2: ffff888020ff2258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:360 [inline] #2: ffff888020ff2258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:187 [inline] #2: ffff888020ff2258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3795 [inline] #2: ffff888020ff2258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x12e6/0x3bb0 net/core/dev.c:4213 #3: ffff88802ae2f4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] #3: ffff88802ae2f4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4335 [inline] #3: ffff88802ae2f4d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x1c4/0x5f0 net/sched/sch_generic.c:340 #4: ffffffff8cf25400 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x40 include/linux/rcupdate.h:327 #5: ffffffff8cf25400 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x40 include/linux/rcupdate.h:327 stack backtrace: CPU: 0 PID: 5540 Comm: syz-executor.0 Not tainted 6.3.0-rc7-syzkaller-g6a8f57ae2eb0 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/30/2023 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106 print_deadlock_bug kernel/locking/lockdep.c:2991 [inline] check_deadlock kernel/locking/lockdep.c:3034 [inline] validate_chain+0x472a/0x58e0 kernel/locking/lockdep.c:3819 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056 lock_acquire+0x1e1/0x520 kernel/locking/lockdep.c:5669 __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:350 [inline] __netif_tx_lock include/linux/netdevice.h:4335 [inline] __dev_queue_xmit+0x17f4/0x3bb0 net/core/dev.c:4243 neigh_output include/net/neighbour.h:546 [inline] ip_finish_output2+0xdd5/0x1290 net/ipv4/ip_output.c:228 iptunnel_xmit+0x510/0x930 net/ipv4/ip_tunnel_core.c:82 ip_tunnel_xmit+0x22ea/0x2c60 net/ipv4/ip_tunnel.c:813 __gre_xmit net/ipv4/ip_gre.c:469 [inline] erspan_xmit+0xad8/0x1540 net/ipv4/ip_gre.c:715 __netdev_start_xmit include/linux/netdevice.h:4884 [inline] netdev_start_xmit include/linux/netdevice.h:4898 [inline] xmit_one net/core/dev.c:3581 [inline] dev_hard_start_xmit+0x241/0x750 net/core/dev.c:3597 sch_direct_xmit+0x2b6/0x5f0 net/sched/sch_generic.c:342 __dev_xmit_skb net/core/dev.c:3808 [inline] __dev_queue_xmit+0x1a6b/0x3bb0 net/core/dev.c:4213 neigh_output include/net/neighbour.h:546 [inline] ip_finish_output2+0xdd5/0x1290 net/ipv4/ip_output.c:228 dst_output include/net/dst.h:444 [inline] ip_local_out net/ipv4/ip_output.c:126 [inline] ip_send_skb+0x117/0x1b0 net/ipv4/ip_output.c:1586 udp_send_skb+0xa33/0x1420 net/ipv4/udp.c:978 udp_sendmsg+0x1f10/0x2d20 net/ipv4/udp.c:1265 udpv6_sendmsg+0xda1/0x3060 net/ipv6/udp.c:1399 sock_sendmsg_nosec net/socket.c:724 [inline] sock_sendmsg net/socket.c:747 [inline] ____sys_sendmsg+0x58f/0x890 net/socket.c:2501 ___sys_sendmsg net/socket.c:2555 [inline] __sys_sendmmsg+0x3af/0x730 net/socket.c:2641 __do_sys_sendmmsg net/socket.c:2670 [inline] __se_sys_sendmmsg net/socket.c:2667 [inline] __x64_sys_sendmmsg+0xa0/0xb0 net/socket.c:2667 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f19a16890e9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f19a277c168 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 00007f19a179bf60 RCX: 00007f19a16890e9 RDX: 0000000000000001 RSI: 0000000020004d80 RDI: 0000000000000004 RBP: 00007f19a16e308d R08: 0000000000000000 R09: 0000000000000000 R10: 0000000004000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffd375e977f R14: 00007f19a277c300 R15: 0000000000022000