============================================ WARNING: possible recursive locking detected 6.6.0-syzkaller-12401-g8f6f76a6a29f #0 Not tainted -------------------------------------------- syz-executor.0/5421 is trying to acquire lock: ffff888020fa50d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff888020fa50d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4381 [inline] ffff888020fa50d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __dev_queue_xmit+0x1694/0x3a30 net/core/dev.c:4340 but task is already holding lock: ffff88807898a0d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff88807898a0d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4381 [inline] ffff88807898a0d8 (_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.0/5421: #0: ffffffff8d92d1e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:301 [inline] #0: ffffffff8d92d1e0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:747 [inline] #0: ffffffff8d92d1e0 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x467/0x1360 net/ipv4/ip_output.c:228 #1: ffffffff8d92d240 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #1: ffffffff8d92d240 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:799 [inline] #1: ffffffff8d92d240 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x2c4/0x3a30 net/core/dev.c:4269 #2: ffff8881482df258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] #2: ffff8881482df258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:194 [inline] #2: ffff8881482df258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3757 [inline] #2: ffff8881482df258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x1242/0x3a30 net/core/dev.c:4310 #3: ffff88807898a0d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] #3: ffff88807898a0d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4381 [inline] #3: ffff88807898a0d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x1c4/0x5f0 net/sched/sch_generic.c:340 #4: ffffffff8d92d1e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:301 [inline] #4: ffffffff8d92d1e0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:747 [inline] #4: ffffffff8d92d1e0 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x467/0x1360 net/ipv4/ip_output.c:228 #5: ffffffff8d92d240 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #5: ffffffff8d92d240 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:799 [inline] #5: ffffffff8d92d240 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x2c4/0x3a30 net/core/dev.c:4269 stack backtrace: CPU: 1 PID: 5421 Comm: syz-executor.0 Not tainted 6.6.0-syzkaller-12401-g8f6f76a6a29f #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106 check_deadlock kernel/locking/lockdep.c:3062 [inline] validate_chain kernel/locking/lockdep.c:3855 [inline] __lock_acquire+0x6a81/0x7f70 kernel/locking/lockdep.c:5136 lock_acquire+0x1e3/0x520 kernel/locking/lockdep.c:5753 __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] __netif_tx_lock include/linux/netdevice.h:4381 [inline] __dev_queue_xmit+0x1694/0x3a30 net/core/dev.c:4340 neigh_output include/net/neighbour.h:542 [inline] ip_finish_output2+0xe6d/0x1360 net/ipv4/ip_output.c:235 iptunnel_xmit+0x540/0x9b0 net/ipv4/ip_tunnel_core.c:82 ip_tunnel_xmit+0x20d8/0x2940 net/ipv4/ip_tunnel.c:831 erspan_xmit+0x9c6/0x13e0 net/ipv4/ip_gre.c:717 __netdev_start_xmit include/linux/netdevice.h:4918 [inline] netdev_start_xmit include/linux/netdevice.h:4932 [inline] xmit_one net/core/dev.c:3543 [inline] dev_hard_start_xmit+0x241/0x750 net/core/dev.c:3559 sch_direct_xmit+0x2b6/0x5f0 net/sched/sch_generic.c:342 __dev_xmit_skb net/core/dev.c:3770 [inline] __dev_queue_xmit+0x18ee/0x3a30 net/core/dev.c:4310 neigh_output include/net/neighbour.h:542 [inline] ip_finish_output2+0xe6d/0x1360 net/ipv4/ip_output.c:235 dst_output include/net/dst.h:451 [inline] ip_local_out net/ipv4/ip_output.c:129 [inline] ip_send_skb+0x117/0x1b0 net/ipv4/ip_output.c:1489 udp_send_skb+0xa6d/0x13e0 net/ipv4/udp.c:963 udp_sendmsg+0x1c1b/0x2a70 net/ipv4/udp.c:1250 udpv6_sendmsg+0x135d/0x3250 net/ipv6/udp.c:1390 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg net/socket.c:745 [inline] ____sys_sendmsg+0x592/0x890 net/socket.c:2588 ___sys_sendmsg net/socket.c:2642 [inline] __sys_sendmmsg+0x3b2/0x730 net/socket.c:2728 __do_sys_sendmmsg net/socket.c:2757 [inline] __se_sys_sendmmsg net/socket.c:2754 [inline] __x64_sys_sendmmsg+0xa0/0xb0 net/socket.c:2754 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x63/0x6b RIP: 0033:0x7f90d3a798a9 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 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f90d4c160c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 00007f90d3b8bf60 RCX: 00007f90d3a798a9 RDX: 0000000000000001 RSI: 0000000020004d80 RDI: 0000000000000004 RBP: 00007f90d3ad5074 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000004000000 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000000b R14: 00007f90d3b8bf60 R15: 00007ffd586e7e88