============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.1.111/4809 is trying to acquire lock:
ffff88807a5fda18 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline]
ffff88807a5fda18 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3909 [inline]
ffff88807a5fda18 (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:
ffff888061c96258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:374 [inline]
ffff888061c96258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:173 [inline]
ffff888061c96258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3871 [inline]
ffff888061c96258 (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
15 locks held by syz.1.111/4809:
#0: ffff88807e2c80e0 (&type->s_umount_key#72/1){+.+.}-{3:3}, at: alloc_super+0x201/0x950 fs/super.c:229
#1: ffffffff8c111260 (console_lock){+.+.}-{0:0}, at: vprintk_emit+0xa7/0x150 kernel/printk/printk.c:2273
#2: ffffc90000dd0be0 ((&ndev->rs_timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:45 [inline]
#2: ffffc90000dd0be0 ((&ndev->rs_timer)){+.-.}-{0:0}, at: call_timer_fn+0xbb/0x530 kernel/time/timer.c:1441
#3: ffffffff8c11c720 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312
#4: ffffffff8c11c780 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
#5: ffffffff8c11c780 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
#6: ffff888061c96258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:374 [inline]
#6: ffff888061c96258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:173 [inline]
#6: ffff888061c96258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3871 [inline]
#6: ffff888061c96258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x10b9/0x2ed0 net/core/dev.c:4253
#7: ffffffff8c11c780 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
#8: ffffffff8c11c780 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
#9: ffff88807a5fd948 (dev->qdisc_running_key ?: &qdisc_running_key){+...}-{0:0}, at: neigh_output include/net/neighbour.h:509 [inline]
#9: ffff88807a5fd948 (dev->qdisc_running_key ?: &qdisc_running_key){+...}-{0:0}, at: ip6_finish_output2+0x1070/0x1500 net/ipv6/ip6_output.c:130
#10: ffff88814cfff4a0 (k-slock-AF_INET6){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:374 [inline]
#10: ffff88814cfff4a0 (k-slock-AF_INET6){+...}-{2:2}, at: icmpv6_xmit_lock net/ipv6/icmp.c:118 [inline]
#10: ffff88814cfff4a0 (k-slock-AF_INET6){+...}-{2:2}, at: icmp6_send+0xa93/0x16e0 net/ipv6/icmp.c:551
#11: ffffffff8c11c720 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312
#12: ffffffff8c11c720 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
#13: ffffffff8c11c780 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
#14: ffffffff8c11c780 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313
stack backtrace:
CPU: 1 PID: 4809 Comm: syz.1.111 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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:364 [inline]
__dev_xmit_skb net/core/dev.c:3909 [inline]
__dev_queue_xmit+0x1f6e/0x2ed0 net/core/dev.c:4253
neigh_output include/net/neighbour.h:509 [inline]
ip6_finish_output2+0x1070/0x1500 net/ipv6/ip6_output.c:130
ip6_send_skb+0x1b9/0x360 net/ipv6/ip6_output.c:1951
icmp6_send+0x113e/0x16e0 net/ipv6/icmp.c:630
__icmpv6_send include/linux/icmpv6.h:28 [inline]
icmpv6_send include/linux/icmpv6.h:49 [inline]
ip6_link_failure+0x35/0x490 net/ipv6/route.c:2788
dst_link_failure include/net/dst.h:422 [inline]
ipip6_tunnel_xmit net/ipv6/sit.c:1045 [inline]
sit_tunnel_xmit+0xa86/0x2250 net/ipv6/sit.c:1082
__netdev_start_xmit include/linux/netdevice.h:5036 [inline]
netdev_start_xmit include/linux/netdevice.h:5050 [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:345
qdisc_restart net/sched/sch_generic.c:410 [inline]
__qdisc_run+0xaaa/0x14a0 net/sched/sch_generic.c:418
__dev_xmit_skb net/core/dev.c:3942 [inline]
__dev_queue_xmit+0xeb9/0x2ed0 net/core/dev.c:4253
neigh_output include/net/neighbour.h:509 [inline]
ip6_finish_output2+0x1070/0x1500 net/ipv6/ip6_output.c:130
ip6tunnel_xmit+0x1a6/0x3d0 include/net/ip6_tunnel.h:160
ip6_tnl_xmit+0x1d7a/0x24b0 net/ipv6/ip6_tunnel.c:1270
__gre6_xmit+0x960/0xc70 net/ipv6/ip6_gre.c:787
ip6gre_xmit_ipv6 net/ipv6/ip6_gre.c:843 [inline]
ip6gre_tunnel_xmit+0xb35/0xf10 net/ipv6/ip6_gre.c:915
__netdev_start_xmit include/linux/netdevice.h:5036 [inline]
netdev_start_xmit include/linux/netdevice.h:5050 [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:345
__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:3956
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:576
__do_softirq kernel/softirq.c:610 [inline]
invoke_softirq kernel/softirq.c:450 [inline]
__irq_exit_rcu+0x12f/0x220 kernel/softirq.c:659
irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
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 4c 94 18 00 eb 18 e8 45 94 18 00 e8 80 af 42 08 48 83 7c 24 28 00 74 e7 e8 33 94 18 00 fb 31 ff <89> de e8 89 97 18 00 85 db 0f 94 c0 22 44 24 17 3c 01 75 1f e8 17
RSP: 0018:ffffc9000356f780 EFLAGS: 00000246
RAX: ffffffff815f37dd RBX: 0000000000000000 RCX: ffff888025150000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000356f9f0 R08: dffffc0000000000 R09: fffffbfff1ff5419
R10: fffffbfff1ff5419 R11: 1ffffffff1ff5418 R12: 1ffffffff194c7e9
R13: dffffc0000000000 R14: 0000000000000000 R15: 1ffffffff194c7e2
vprintk_emit+0xc0/0x150 kernel/printk/printk.c:2274
_printk+0xcc/0x110 kernel/printk/printk.c:2299
udf_fill_super+0x1340/0x18f0 fs/udf/super.c:2308
mount_bdev+0x287/0x3c0 fs/super.c:1400
legacy_get_tree+0xe6/0x180 fs/fs_context.c:611
vfs_get_tree+0x88/0x270 fs/super.c:1530
do_new_mount+0x24a/0xa40 fs/namespace.c:3034
do_mount fs/namespace.c:3377 [inline]
__do_sys_mount fs/namespace.c:3585 [inline]
__se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3562
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fcc55b9deea
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 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:00007fcc53de1e68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fcc53de1ef0 RCX: 00007fcc55b9deea
RDX: 0000200000000280 RSI: 00002000000001c0 RDI: 00007fcc53de1eb0
RBP: 0000200000000280 R08: 00007fcc53de1ef0 R09: 00000000010004d0
R10: 00000000010004d0 R11: 0000000000000246 R12: 00002000000001c0
R13: 00007fcc53de1eb0 R14: 0000000000000a1b R15: 0000200000000340
----------------
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 4c 94 18 00 call 0x18945a
e: eb 18 jmp 0x28
10: e8 45 94 18 00 call 0x18945a
15: e8 80 af 42 08 call 0x842af9a
1a: 48 83 7c 24 28 00 cmpq $0x0,0x28(%rsp)
20: 74 e7 je 0x9
22: e8 33 94 18 00 call 0x18945a
27: fb sti
28: 31 ff xor %edi,%edi
* 2a: 89 de mov %ebx,%esi <-- trapping instruction
2c: e8 89 97 18 00 call 0x1897ba
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: 17 (bad)