============================================
WARNING: possible recursive locking detected
5.15.189-syzkaller #0 Not tainted
--------------------------------------------
syslogd/3543 is trying to acquire lock:
ffff88807be03a18 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline]
ffff88807be03a18 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3909 [inline]
ffff88807be03a18 (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:
ffff88807852c258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:373 [inline]
ffff88807852c258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:173 [inline]
ffff88807852c258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3871 [inline]
ffff88807852c258 (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
9 locks held by syslogd/3543:
#0: ffff88802c3add98 (&u->iolock){+.+.}-{3:3}, at: __unix_dgram_recvmsg+0x1e1/0xd50 net/unix/af_unix.c:2312
#1: ffffffff8c11c360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311
#2: ffffc90000007be0 ((&ndev->rs_timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:45 [inline]
#2: ffffc90000007be0 ((&ndev->rs_timer)){+.-.}-{0:0}, at: call_timer_fn+0xbb/0x530 kernel/time/timer.c:1441
#3: ffffffff8c11c360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311
#4: ffffffff8c11c3c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312
#5: ffffffff8c11c3c0 (
rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312
#6: ffff88807852c258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: spin_trylock include/linux/spinlock.h:373 [inline]
#6: ffff88807852c258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:173 [inline]
#6: ffff88807852c258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3871 [inline]
#6: ffff88807852c258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+.-.}-{2:2}, at: __dev_queue_xmit+0x10b9/0x2ed0 net/core/dev.c:4253
#7: ffffffff8c11c3c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312
#8: ffffffff8c11c3c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312
stack backtrace:
CPU: 0 PID: 3543 Comm: syslogd Not tainted 5.15.189-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
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: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:3957
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:bpf_ksym_find kernel/bpf/core.c:693 [inline]
RIP: 0010:is_bpf_text_address+0x238/0x270 kernel/bpf/core.c:726
Code: 4e f4 f3 ff eb 24 e8 47 f4 f3 ff c6 05 04 df d1 0b 01 48 c7 c7 c0 93 10 8a be 01 03 00 00 48 c7 c2 60 94 10 8a e8 98 b5 19 08 <48> 85 ed 0f 95 c0 48 81 fd a0 00 00 00 0f 95 c3 20 c3 e8 f1 87 e0
RSP: 0018:ffffc90002e4f4e0 EFLAGS: 00000293
RAX: ffffffff8183cfa0 RBX: 0000000000000001 RCX: ffff88807e52d940
RDX: 0000000000000000 RSI: ffffffff8a599320 RDI: ffffffff8a5992e0
RBP: 0000000000000000 R08: dffffc0000000000 R09: fffffbfff1ff6e19
R10: fffffbfff1ff6e19 R11: 1ffffffff1ff6e18 R12: dffffc0000000000
R13: 0000000000000172 R14: 0000000000000000 R15: ffffffffa0046000
kernel_text_address kernel/extable.c:151 [inline]
__kernel_text_address+0x9a/0x100 kernel/extable.c:105
unwind_get_return_address+0x49/0x80 arch/x86/kernel/unwind_orc.c:323
arch_stack_walk+0xf2/0x140 arch/x86/kernel/stacktrace.c:26
stack_trace_save+0x98/0xe0 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:46
kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
kasan_slab_free include/linux/kasan.h:230 [inline]
slab_free_hook mm/slub.c:1705 [inline]
slab_free_freelist_hook+0xea/0x170 mm/slub.c:1731
slab_free mm/slub.c:3499 [inline]
kmem_cache_free+0x8f/0x210 mm/slub.c:3515
skb_free_datagram+0x25/0xe0 net/core/datagram.c:325
__unix_dgram_recvmsg+0x9cc/0xd50 net/unix/af_unix.c:2395
sock_recvmsg_nosec net/socket.c:966 [inline]
sock_recvmsg net/socket.c:984 [inline]
sock_read_iter+0x2a2/0x340 net/socket.c:1057
call_read_iter include/linux/fs.h:2166 [inline]
new_sync_read fs/read_write.c:404 [inline]
vfs_read+0x725/0xcf0 fs/read_write.c:485
ksys_read+0x14d/0x250 fs/read_write.c:623
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: 0033:0x7ff4cb131407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffe57938a20 EFLAGS: 00000202 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007ff4cafe1c80 RCX: 00007ff4cb131407
RDX: 00000000000000ff RSI: 000055feca926950 RDI: 0000000000000000
RBP: 000055feca926910 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 000055feca9269c7
R13: 0000000000000000 R14: 000055feca926950 R15: 000055fe961b3d98
vkms_vblank_simulate: vblank timer overrun
GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog
----------------
Code disassembly (best guess):
0: 4e f4 rex.WRX hlt
2: f3 ff repz (bad)
4: eb 24 jmp 0x2a
6: e8 47 f4 f3 ff call 0xfff3f452
b: c6 05 04 df d1 0b 01 movb $0x1,0xbd1df04(%rip) # 0xbd1df16
12: 48 c7 c7 c0 93 10 8a mov $0xffffffff8a1093c0,%rdi
19: be 01 03 00 00 mov $0x301,%esi
1e: 48 c7 c2 60 94 10 8a mov $0xffffffff8a109460,%rdx
25: e8 98 b5 19 08 call 0x819b5c2
* 2a: 48 85 ed test %rbp,%rbp <-- trapping instruction
2d: 0f 95 c0 setne %al
30: 48 81 fd a0 00 00 00 cmp $0xa0,%rbp
37: 0f 95 c3 setne %bl
3a: 20 c3 and %al,%bl
3c: e8 .byte 0xe8
3d: f1 int1
3e: 87 e0 xchg %esp,%eax