syzkaller0: entered promiscuous mode
syzkaller0: entered allmulticast mode
============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.0.17/5936 is trying to acquire lock:
ffff888073d78108 (&sch->root_lock_key#43){+...}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffff888073d78108 (&sch->root_lock_key#43){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3918 [inline]
ffff888073d78108 (&sch->root_lock_key#43){+...}-{2:2}, at: __dev_queue_xmit+0xb01/0x3640 net/core/dev.c:4434

but task is already holding lock:
ffff888073d78108 (&sch->root_lock_key#43){+...}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffff888073d78108 (&sch->root_lock_key#43){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3918 [inline]
ffff888073d78108 (&sch->root_lock_key#43){+...}-{2:2}, at: __dev_queue_xmit+0xb01/0x3640 net/core/dev.c:4434

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&sch->root_lock_key#43);
  lock(&sch->root_lock_key#43);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

3 locks held by syz.0.17/5936:
 #0: ffffffff8d131e00 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
 #0: ffffffff8d131e00 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:838 [inline]
 #0: ffffffff8d131e00 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x275/0x3640 net/core/dev.c:4393
 #1: ffff888073d78108 (&sch->root_lock_key#43){+...}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
 #1: ffff888073d78108 (&sch->root_lock_key#43){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3918 [inline]
 #1: ffff888073d78108 (&sch->root_lock_key#43){+...}-{2:2}, at: __dev_queue_xmit+0xb01/0x3640 net/core/dev.c:4434
 #2: ffffffff8d131e00 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
 #2: ffffffff8d131e00 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:838 [inline]
 #2: ffffffff8d131e00 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x275/0x3640 net/core/dev.c:4393

stack backtrace:
CPU: 0 PID: 5936 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 check_deadlock kernel/locking/lockdep.c:3062 [inline]
 validate_chain kernel/locking/lockdep.c:3856 [inline]
 __lock_acquire+0x6809/0x7d80 kernel/locking/lockdep.c:5137
 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
 __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:3918 [inline]
 __dev_queue_xmit+0xb01/0x3640 net/core/dev.c:4434
 sch_frag_xmit_hook+0x2a8/0x11d0 net/sched/sch_frag.c:148
 tcf_mirred_forward net/sched/act_mirred.c:215 [inline]
 tcf_mirred_to_dev net/sched/act_mirred.c:-1 [inline]
 tcf_mirred_act+0xbd6/0x1350 net/sched/act_mirred.c:337
 tc_act include/net/tc_wrapper.h:221 [inline]
 tcf_action_exec+0x1a9/0x5d0 net/sched/act_api.c:1097
 tcf_exts_exec include/net/pkt_cls.h:363 [inline]
 basic_classify+0x1b2/0x2d0 net/sched/cls_basic.c:54
 tc_classify include/net/tc_wrapper.h:227 [inline]
 __tcf_classify net/sched/cls_api.c:1754 [inline]
 tcf_classify+0x421/0xfc0 net/sched/cls_api.c:1850
 qfq_classify net/sched/sch_qfq.c:715 [inline]
 qfq_enqueue+0x320/0x12e0 net/sched/sch_qfq.c:1239
 dev_qdisc_enqueue+0x48/0x220 net/core/dev.c:3854
 __dev_xmit_skb net/core/dev.c:3943 [inline]
 __dev_queue_xmit+0xcd4/0x3640 net/core/dev.c:4434
 packet_snd net/packet/af_packet.c:3161 [inline]
 packet_sendmsg+0x38d9/0x4a30 net/packet/af_packet.c:3193
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x61b/0x980 net/socket.c:2595
 ___sys_sendmsg+0x2a6/0x360 net/socket.c:2649
 __sys_sendmsg net/socket.c:2678 [inline]
 __do_sys_sendmsg net/socket.c:2687 [inline]
 __se_sys_sendmsg+0x1d0/0x2c0 net/socket.c:2685
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f681919e159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc263d59f8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f6819425fa0 RCX: 00007f681919e159
RDX: 0000000000004005 RSI: 0000200000000280 RDI: 0000000000000006
RBP: 00007f6819235024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6819425fac R14: 00007f6819425fa0 R15: 00007f6819425fa0
 </TASK>