============================================ WARNING: possible recursive locking detected 6.1.128-syzkaller #0 Not tainted -------------------------------------------- syz.0.363/5385 is trying to acquire lock: ffff8880246f2218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff8880246f2218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3894 [inline] ffff8880246f2218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x22db/0x3d50 net/core/dev.c:4269 but task is already holding lock: ffff888055cd3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] ffff888055cd3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline] ffff888055cd3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3851 [inline] ffff888055cd3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x12c7/0x3d50 net/core/dev.c:4269 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock); lock(dev->qdisc_tx_busylock ?: &qdisc_tx_busylock); *** DEADLOCK *** May be due to missing lock nesting notation 7 locks held by syz.0.363/5385: #0: ffffffff8d32b0c0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #0: ffffffff8d32b0c0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #0: ffffffff8d32b0c0 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x402/0x1330 net/ipv4/ip_output.c:221 #1: ffffffff8d32b120 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #1: ffffffff8d32b120 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:843 [inline] #1: ffffffff8d32b120 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x2d6/0x3d50 net/core/dev.c:4226 #2: ffffffff8d32b0c0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #2: ffffffff8d32b0c0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #2: ffffffff8d32b0c0 (rcu_read_lock){....}-{1:2}, at: br_dev_xmit+0x212/0x18e0 net/bridge/br_device.c:49 #3: ffffffff8d32b120 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #3: ffffffff8d32b120 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:843 [inline] #3: ffffffff8d32b120 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x2d6/0x3d50 net/core/dev.c:4226 #4: ffff888055cd3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] #4: ffff888055cd3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:195 [inline] #4: ffff888055cd3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3851 [inline] #4: ffff888055cd3258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x12c7/0x3d50 net/core/dev.c:4269 #5: ffffffff8d32b0c0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline] #5: ffffffff8d32b0c0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline] #5: ffffffff8d32b0c0 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x402/0x1330 net/ipv4/ip_output.c:221 #6: ffffffff8d32b120 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #6: ffffffff8d32b120 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:843 [inline] #6: ffffffff8d32b120 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x2d6/0x3d50 net/core/dev.c:4226 stack backtrace: CPU: 1 PID: 5385 Comm: syz.0.363 Not tainted 6.1.128-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106 print_deadlock_bug kernel/locking/lockdep.c:2983 [inline] check_deadlock kernel/locking/lockdep.c:3026 [inline] validate_chain+0x4711/0x5950 kernel/locking/lockdep.c:3812 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] __dev_xmit_skb net/core/dev.c:3894 [inline] __dev_queue_xmit+0x22db/0x3d50 net/core/dev.c:4269 dev_queue_xmit include/linux/netdevice.h:3043 [inline] neigh_hh_output include/net/neighbour.h:528 [inline] neigh_output include/net/neighbour.h:542 [inline] ip_finish_output2+0xcfc/0x1330 net/ipv4/ip_output.c:228 iptunnel_xmit+0x513/0x920 net/ipv4/ip_tunnel_core.c:82 ip_tunnel_xmit+0x1f87/0x2690 net/ipv4/ip_tunnel.c:858 __gre_xmit net/ipv4/ip_gre.c:474 [inline] gre_tap_xmit+0x4eb/0x6e0 net/ipv4/ip_gre.c:751 __netdev_start_xmit include/linux/netdevice.h:4888 [inline] netdev_start_xmit include/linux/netdevice.h:4902 [inline] xmit_one net/core/dev.c:3627 [inline] dev_hard_start_xmit+0x261/0x8c0 net/core/dev.c:3643 sch_direct_xmit+0x2b2/0x5e0 net/sched/sch_generic.c:342 __dev_xmit_skb net/core/dev.c:3864 [inline] __dev_queue_xmit+0x1a7a/0x3d50 net/core/dev.c:4269 dev_queue_xmit include/linux/netdevice.h:3043 [inline] br_dev_queue_push_xmit+0x6fe/0x8c0 net/bridge/br_forward.c:53 NF_HOOK+0x39f/0x450 include/linux/netfilter.h:302 br_forward_finish+0xe1/0x130 net/bridge/br_forward.c:66 NF_HOOK+0x39f/0x450 include/linux/netfilter.h:302 __br_forward+0x430/0x5f0 net/bridge/br_forward.c:115 deliver_clone net/bridge/br_forward.c:131 [inline] maybe_deliver+0xb3/0x150 net/bridge/br_forward.c:189 br_flood+0x2e7/0x440 net/bridge/br_forward.c:231 br_dev_xmit+0x1194/0x18e0 __netdev_start_xmit include/linux/netdevice.h:4888 [inline] netdev_start_xmit include/linux/netdevice.h:4902 [inline] xmit_one net/core/dev.c:3627 [inline] dev_hard_start_xmit+0x261/0x8c0 net/core/dev.c:3643 __dev_queue_xmit+0x1b5d/0x3d50 net/core/dev.c:4303 dev_queue_xmit include/linux/netdevice.h:3043 [inline] neigh_hh_output include/net/neighbour.h:528 [inline] neigh_output include/net/neighbour.h:542 [inline] ip_finish_output2+0xcfc/0x1330 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+0x113/0x1a0 net/ipv4/ip_output.c:1599 udp_send_skb+0xa33/0x1420 net/ipv4/udp.c:993 udp_sendmsg+0x1d10/0x2ad0 net/ipv4/udp.c:1281 sock_sendmsg_nosec net/socket.c:718 [inline] __sock_sendmsg net/socket.c:730 [inline] ____sys_sendmsg+0x5a5/0x8f0 net/socket.c:2519 ___sys_sendmsg net/socket.c:2573 [inline] __sys_sendmmsg+0x3ab/0x730 net/socket.c:2659 __do_sys_sendmmsg net/socket.c:2688 [inline] __se_sys_sendmmsg net/socket.c:2685 [inline] __x64_sys_sendmmsg+0x9c/0xb0 net/socket.c:2685 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f11d938cde9 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f11da29a038 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 00007f11d95a6160 RCX: 00007f11d938cde9 RDX: 000000000800001d RSI: 0000400000007fc0 RDI: 0000000000000003 RBP: 00007f11d940e2a0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f11d95a6160 R15: 00007ffe7ae46068 syz.0.363 (5385) used greatest stack depth: 18264 bytes left