============================================
WARNING: possible recursive locking detected
5.15.184-syzkaller #0 Not tainted
--------------------------------------------
kworker/u4:7/4246 is trying to acquire lock:
ffff888022c2a218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline]
ffff888022c2a218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3909 [inline]
ffff888022c2a218 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x1f6e/0x2ed0 net/core/dev.c:4253
but task is already holding lock:
ffff888077242258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:373 [inline]
ffff888077242258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:173 [inline]
ffff888077242258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3871 [inline]
ffff888077242258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x10b9/0x2ed0 net/core/dev.c:4253
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
10 locks held by kworker/u4:7/4246:
#0: ffff888016879138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
#1: ffffc9000310fd00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
#2: ffffffff8d22a848 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xa/0x50 net/core/link_watch.c:251
#3: ffffc90000007be0 ((&ndev->rs_timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:45 [inline]
#3: ffffc90000007be0 ((&ndev->rs_timer)){+.-.}-{0:0}, at: call_timer_fn+0xbb/0x530 kernel/time/timer.c:1441
#4: ffffffff8c11c060 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311
#5: ffffffff8c11c0c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312
#6: ffffffff8c11c0c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312
#7: ffff888077242258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:373 [inline]
#7: ffff888077242258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:173 [inline]
#7: ffff888077242258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3871 [inline]
#7: ffff888077242258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x10b9/0x2ed0 net/core/dev.c:4253
#8: ffffffff8c11c0c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312
#9: ffffffff8c11c0c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312
stack backtrace:
CPU: 0 PID: 4246 Comm: kworker/u4:7 Not tainted 5.15.184-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: events_unbound linkwatch_event
Call Trace:
dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
__lock_acquire+0x1227/0x7c60 kernel/locking/lockdep.c:-1
lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:363 [inline]
__dev_xmit_skb net/core/dev.c:3909 [inline]
__dev_queue_xmit+0x1f6e/0x2ed0 net/core/dev.c:4253
neigh_hh_output include/net/neighbour.h:493 [inline]
neigh_output include/net/neighbour.h:507 [inline]
ip_finish_output2+0xc69/0x1080 net/ipv4/ip_output.c:228
iptunnel_xmit+0x525/0x960 net/ipv4/ip_tunnel_core.c:82
ip_tunnel_xmit+0x1b6f/0x2240 net/ipv4/ip_tunnel.c:838
__gre_xmit net/ipv4/ip_gre.c:474 [inline]
gre_tap_xmit+0x4f9/0x6e0 net/ipv4/ip_gre.c:751
__netdev_start_xmit include/linux/netdevice.h:5027 [inline]
netdev_start_xmit include/linux/netdevice.h:5041 [inline]
xmit_one net/core/dev.c:3649 [inline]
dev_hard_start_xmit+0x2a5/0x7e0 net/core/dev.c:3665
sch_direct_xmit+0x24e/0x4a0 net/sched/sch_generic.c:342
__dev_xmit_skb net/core/dev.c:3884 [inline]
__dev_queue_xmit+0x170e/0x2ed0 net/core/dev.c:4253
neigh_hh_output include/net/neighbour.h:493 [inline]
neigh_output include/net/neighbour.h:507 [inline]
ip6_finish_output2+0x1035/0x1500 net/ipv6/ip6_output.c:130
dst_output include/net/dst.h:452 [inline]
NF_HOOK include/linux/netfilter.h:302 [inline]
ndisc_send_skb+0xbea/0x14a0 net/ipv6/ndisc.c:513
addrconf_rs_timer+0x2b8/0x600 net/ipv6/addrconf.c:3962
call_timer_fn+0x16c/0x530 kernel/time/timer.c:1451
expire_timers kernel/time/timer.c:1496 [inline]
__run_timers+0x525/0x7c0 kernel/time/timer.c:1767
run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1780
handle_softirqs+0x328/0x820 kernel/softirq.c:558
__do_softirq kernel/softirq.c:592 [inline]
invoke_softirq kernel/softirq.c:432 [inline]
__irq_exit_rcu+0x12f/0x220 kernel/softirq.c:641
irq_exit_rcu+0x5/0x20 kernel/softirq.c:653
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:console_unlock+0xd90/0x1200 kernel/printk/printk.c:2749
Code: 00 48 83 7c 24 28 00 75 19 e8 dc 9e 18 00 eb 18 e8 d5 9e 18 00 e8 50 0a 42 08 48 83 7c 24 28 00 74 e7 e8 c3 9e 18 00 fb 31 ff <89> de e8 19 a2 18 00 85 db 0f 94 c0 22 44 24 17 3c 01 75 1f e8 a7
RSP: 0018:ffffc9000310f620 EFLAGS: 00000246
RAX: ffffffff815f227d RBX: 0000000000000001 RCX: ffff88802b3dbb80
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000310f890 R08: dffffc0000000000 R09: fffffbfff1ff361a
R10: fffffbfff1ff361a R11: 1ffffffff1ff3619 R12: 1ffffffff194c731
R13: dffffc0000000000 R14: 0000000000000000 R15: 1ffffffff194c72a
vprintk_emit+0xc0/0x150 kernel/printk/printk.c:2274
_printk+0xcc/0x110 kernel/printk/printk.c:2299
addrconf_notify+0xa5b/0xf00 net/ipv6/addrconf.c:3662
notifier_call_chain kernel/notifier.c:83 [inline]
raw_notifier_call_chain+0xcb/0x160 kernel/notifier.c:391
netdev_state_change+0xd2/0x140 net/core/dev.c:1440
linkwatch_do_dev+0x10d/0x160 net/core/link_watch.c:167
__linkwatch_run_queue+0x4a9/0x7b0 net/core/link_watch.c:213
linkwatch_event+0x48/0x50 net/core/link_watch.c:252
process_one_work+0x863/0x1000 kernel/workqueue.c:2310
worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog
----------------
Code disassembly (best guess):
0: 00 48 83 add %cl,-0x7d(%rax)
3: 7c 24 jl 0x29
5: 28 00 sub %al,(%rax)
7: 75 19 jne 0x22
9: e8 dc 9e 18 00 call 0x189eea
e: eb 18 jmp 0x28
10: e8 d5 9e 18 00 call 0x189eea
15: e8 50 0a 42 08 call 0x8420a6a
1a: 48 83 7c 24 28 00 cmpq $0x0,0x28(%rsp)
20: 74 e7 je 0x9
22: e8 c3 9e 18 00 call 0x189eea
27: fb sti
28: 31 ff xor %edi,%edi
* 2a: 89 de mov %ebx,%esi <-- trapping instruction
2c: e8 19 a2 18 00 call 0x18a24a
31: 85 db test %ebx,%ebx
33: 0f 94 c0 sete %al
36: 22 44 24 17 and 0x17(%rsp),%al
3a: 3c 01 cmp $0x1,%al
3c: 75 1f jne 0x5d
3e: e8 .byte 0xe8
3f: a7 cmpsl %es:(%rdi),%ds:(%rsi)