INFO: task syz.3.3960:20520 blocked for more than 143 seconds.
Tainted: G L syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.3960 state:D stack:26888 pid:20520 tgid:20519 ppid:5607 task_flags:0x400140 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5510 [inline]
__schedule+0x125c/0x6730 kernel/sched/core.c:7234
__schedule_loop kernel/sched/core.c:7311 [inline]
schedule+0xdd/0x2c0 kernel/sched/core.c:7326
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7383
rwsem_down_read_slowpath+0x5af/0xb40 kernel/locking/rwsem.c:1114
__down_read_common kernel/locking/rwsem.c:1291 [inline]
__down_read kernel/locking/rwsem.c:1304 [inline]
down_read+0xed/0x4c0 kernel/locking/rwsem.c:1576
__super_lock fs/super.c:60 [inline]
super_lock+0x320/0x3f0 fs/super.c:122
__iterate_supers+0x1e0/0x330 fs/super.c:866
ksys_sync+0x87/0xf0 fs/sync.c:102
__do_sys_sync+0xe/0x20 fs/sync.c:111
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f824d39e019
RSP: 002b:00007f824e30f028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f824d625fa0 RCX: 00007f824d39e019
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f824d625fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f824d626038 R14: 00007f824d625fa0 R15: 00007ffc52e96e78
Showing all locks held in the system:
1 lock held by khungtaskd/31:
#0: ffffffff8ebe8200 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#0: ffffffff8ebe8200 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
#0: ffffffff8ebe8200 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775
3 locks held by khugepaged/38:
2 locks held by getty/5368:
#0: ffff8880384ce0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
#1: ffffc900032332e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x14e0 drivers/tty/n_tty.c:2211
5 locks held by kworker/u8:19/7659:
#0: ffff8880b843b520 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:675 [inline]
#0: ffff8880b843b520 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x88/0x140 kernel/sched/core.c:659
#1: ffff8880b8424568 (psi_seq){-.-.}-{0:0}, at: psi_sched_switch kernel/sched/stats.h:218 [inline]
#1: ffff8880b8424568 (psi_seq){-.-.}-{0:0}, at: __schedule+0x2e8e/0x6730 kernel/sched/core.c:7228
#2: ffff8880b8426298 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x124/0x1d0 kernel/time/timer.c:1004
#3: ffffffff9b8e98d8 (&obj_hash[i].lock){-.-.}-{2:2}, at: debug_object_activate+0x144/0x4b0 lib/debugobjects.c:873
#4: ffffffff8ebe8200 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#4: ffffffff8ebe8200 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
#4: ffffffff8ebe8200 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1183 [inline]
#4: ffffffff8ebe8200 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0xbd/0x2090 arch/x86/kernel/unwind_orc.c:495
2 locks held by syz.4.3118/17721:
#0: ffff88807d37c0d8 (&type->s_umount_key#98){++++}-{4:4}, at: __super_lock fs/super.c:58 [inline]
#0: ffff88807d37c0d8 (&type->s_umount_key#98){++++}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
#0: ffff88807d37c0d8 (&type->s_umount_key#98){++++}-{4:4}, at: deactivate_super fs/super.c:509 [inline]
#0: ffff88807d37c0d8 (&type->s_umount_key#98){++++}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:506
#1: ffffffff8f072960 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
1 lock held by syz.3.3960/20520:
#0: ffff88807d37c0d8 (&type->s_umount_key#98){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
#0: ffff88807d37c0d8 (&type->s_umount_key#98){++++}-{4:4}, at: super_lock+0x320/0x3f0 fs/super.c:122
1 lock held by syz.2.4134/21377:
#0: ffff88807d37c0d8 (&type->s_umount_key#98){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
#0: ffff88807d37c0d8 (&type->s_umount_key#98){++++}-{4:4}, at: super_lock+0x320/0x3f0 fs/super.c:122
1 lock held by syz.8.4373/22288:
1 lock held by syz.5.4393/22358:
#0: ffff88807b277678 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock include/linux/mmap_lock.h:592 [inline]
#0: ffff88807b277678 (&mm->mmap_lock){++++}-{4:4}, at: acct_collect+0x54f/0x860 kernel/acct.c:568
1 lock held by syz.5.4393/22360:
#0: ffff88807b277678 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock include/linux/mmap_lock.h:592 [inline]
#0: ffff88807b277678 (&mm->mmap_lock){++++}-{4:4}, at: exit_mm kernel/exit.c:591 [inline]
#0: ffff88807b277678 (&mm->mmap_lock){++++}-{4:4}, at: do_exit+0x7a9/0x2ae0 kernel/exit.c:997
2 locks held by syz.5.4393/22363:
#0: ffff8880b843b520 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:675 [inline]
#0: ffff8880b843b520 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x88/0x140 kernel/sched/core.c:659
#1: ffff8880b8424568 (psi_seq){-.-.}-{0:0}, at: psi_sched_switch kernel/sched/stats.h:218 [inline]
#1: ffff8880b8424568 (psi_seq){-.-.}-{0:0}, at: __schedule+0x2e8e/0x6730 kernel/sched/core.c:7228
2 locks held by syz.8.4395/22375:
1 lock held by syz.0.4400/22396:
#0: ffffffff8ebf3ca8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x19e/0x3c0 kernel/rcu/tree_exp.h:343
1 lock held by syz.6.4401/22402:
2 locks held by syz.6.4401/22403:
1 lock held by dhcpcd/22406:
#0: ffff88802b2a0260 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1713 [inline]
#0: ffff88802b2a0260 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x2c/0xf50 net/packet/af_packet.c:3204
2 locks held by dhcpcd/22407:
#0: ffff88801e366260 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1713 [inline]
#0: ffff88801e366260 (sk_lock-AF_PACKET){+.+.}-{0:0}, at: packet_do_bind+0x2c/0xf50 net/packet/af_packet.c:3204
#1: ffffffff8ebf3ca8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x19e/0x3c0 kernel/rcu/tree_exp.h:343
=============================================
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Call Trace:
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
nmi_cpu_backtrace.cold+0x12d/0x151 lib/nmi_backtrace.c:122
nmi_trigger_cpumask_backtrace+0x21c/0x2a0 lib/nmi_backtrace.c:65
trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
__sys_info lib/sys_info.c:157 [inline]
sys_info+0x141/0x190 lib/sys_info.c:165
check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
watchdog+0xcb1/0x1030 kernel/hung_task.c:561
kthread+0x370/0x450 kernel/kthread.c:436
ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 7661 Comm: kworker/u8:20 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Workqueue: wg-kex-wg0 wg_packet_handshake_send_worker
RIP: 0010:io_serial_in+0x87/0xb0 drivers/tty/serial/8250/8250_port.c:402
Code: ce 66 fc 48 8d 7d 40 44 89 e1 48 b8 00 00 00 00 00 fc ff df 48 89 fa d3 e3 48 c1 ea 03 80 3c 02 00 75 1a 66 03 5d 40 89 da ec <5b> 0f b6 c0 5d 41 5c e9 7d 5f 1b 06 e8 08 57 d7 fc eb a2 e8 91 57
RSP: 0018:ffffc900037b6df8 EFLAGS: 00000002
RAX: dffffc0000000000 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: ffffffff85a39330 RDI: ffffffff9ba0bb40
RBP: ffffffff9ba0bb00 R08: 0000000000000001 R09: 000000000000001f
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000020 R14: fffffbfff37417ba R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff888123dd8000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f566abef2f8 CR3: 0000000073ab0000 CR4: 00000000003526f0
Call Trace:
serial_in drivers/tty/serial/8250/8250.h:128 [inline]
serial_lsr_in drivers/tty/serial/8250/8250.h:150 [inline]
wait_for_lsr+0x13a/0x210 drivers/tty/serial/8250/8250_port.c:1982
serial8250_fifo_wait_for_lsr_thre drivers/tty/serial/8250/8250_port.c:3235 [inline]
serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3300 [inline]
serial8250_console_write+0xdfd/0x1a50 drivers/tty/serial/8250/8250_port.c:3385
console_emit_next_record kernel/printk/printk.c:3183 [inline]
console_flush_one_record+0x790/0xe50 kernel/printk/printk.c:3269
console_flush_all kernel/printk/printk.c:3343 [inline]
__console_flush_and_unlock kernel/printk/printk.c:3373 [inline]
console_unlock+0x103/0x260 kernel/printk/printk.c:3413
vprintk_emit+0x407/0x6b0 kernel/printk/printk.c:2479
_printk+0xcf/0x110 kernel/printk/printk.c:2504
gred_dequeue.cold+0x40/0x4f net/sched/sch_gred.c:273
dequeue_skb net/sched/sch_generic.c:322 [inline]
qdisc_restart net/sched/sch_generic.c:427 [inline]
__qdisc_run+0x1be/0x1b20 net/sched/sch_generic.c:445
qdisc_run include/net/pkt_sched.h:120 [inline]
qdisc_run include/net/pkt_sched.h:117 [inline]
__dev_xmit_skb net/core/dev.c:4297 [inline]
__dev_queue_xmit+0x3104/0x4970 net/core/dev.c:4836
dev_queue_xmit include/linux/netdevice.h:3446 [inline]
neigh_hh_output include/net/neighbour.h:544 [inline]
neigh_output include/net/neighbour.h:558 [inline]
ip6_finish_output2+0xfd4/0x1ce0 net/ipv6/ip6_output.c:136
__ip6_finish_output+0x357/0xdf0 net/ipv6/ip6_output.c:208
ip6_finish_output net/ipv6/ip6_output.c:219 [inline]
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip6_output+0x2aa/0xa60 net/ipv6/ip6_output.c:246
dst_output include/net/dst.h:470 [inline]
ip6_local_out+0xcb/0x1f0 net/ipv6/output_core.c:128
ip6tunnel_xmit include/net/ip6_tunnel.h:174 [inline]
udp_tunnel6_xmit_skb+0x8ae/0xf20 net/ipv6/ip6_udp_tunnel.c:112
send6+0x4bc/0xc40 drivers/net/wireguard/socket.c:151
wg_socket_send_skb_to_peer+0xf6/0x210 drivers/net/wireguard/socket.c:177
wg_socket_send_buffer_to_peer+0x148/0x1a0 drivers/net/wireguard/socket.c:199
wg_packet_send_handshake_initiation+0x227/0x360 drivers/net/wireguard/send.c:40
wg_packet_handshake_send_worker+0x1c/0x30 drivers/net/wireguard/send.c:51
process_one_work+0xa23/0x1940 kernel/workqueue.c:3322
process_scheduled_works kernel/workqueue.c:3405 [inline]
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486
kthread+0x370/0x450 kernel/kthread.c:436
ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog
GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog