syzbot

INFO: task syz.6.1246:10759 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.1246      state:D stack:26728 pid:10759 tgid:10758 ppid:6203   task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7058
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7115
 __mutex_lock_common kernel/locking/mutex.c:676 [inline]
 __mutex_lock+0x7e6/0x1350 kernel/locking/mutex.c:760
 nfsd_nl_version_get_doit+0x16e/0xb60 fs/nfsd/nfsctl.c:1844
 genl_family_rcv_msg_doit+0x215/0x300 net/netlink/genetlink.c:1115
 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
 genl_rcv_msg+0x60e/0x790 net/netlink/genetlink.c:1210
 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2552
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x82f/0x9e0 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1896
 sock_sendmsg_nosec net/socket.c:714 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:729
 ____sys_sendmsg+0x505/0x830 net/socket.c:2614
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2668
 __sys_sendmsg net/socket.c:2700 [inline]
 __do_sys_sendmsg net/socket.c:2705 [inline]
 __se_sys_sendmsg net/socket.c:2703 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2703
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe75f78ebe9
RSP: 002b:00007fe760599038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fe75f9c5fa0 RCX: 00007fe75f78ebe9
RDX: 0000000000040000 RSI: 0000200000000540 RDI: 0000000000000004
RBP: 00007fe75f811e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe75f9c6038 R14: 00007fe75f9c5fa0 R15: 00007ffe866f46a8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8e139f20 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e139f20 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8e139f20 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
4 locks held by kworker/u8:2/36:
3 locks held by kworker/u8:3/49:
 #0: ffff88801a481148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3211 [inline]
 #0: ffff88801a481148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3319
 #1: ffffc90000b97bc0 ((work_completion)(&map->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3212 [inline]
 #1: ffffc90000b97bc0 ((work_completion)(&map->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3319
 #2: ffffffff8e13f880 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x570 kernel/rcu/tree.c:3815
5 locks held by kworker/u8:6/3518:
 #0: ffff8880b8639f98 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:636
 #1: ffff8880b8624008 (psi_seq){-.-.}-{0:0}, at: psi_task_switch+0x53/0x880 kernel/sched/psi.c:933
 #2: ffff8880799b0768 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: class_wiphy_constructor include/net/cfg80211.h:6212 [inline]
 #2: ffff8880799b0768 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: cfg80211_wiphy_work+0xc4/0x470 net/wireless/core.c:421
 #3: ffff8880b8724008 (psi_seq){-.-.}-{0:0}, at: psi_task_change+0xd9/0x340 kernel/sched/psi.c:919
 #4: ffffffff8e139f20 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #4: ffffffff8e139f20 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #4: ffffffff8e139f20 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1155 [inline]
 #4: ffffffff8e139f20 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0xa5/0x2390 arch/x86/kernel/unwind_orc.c:479
1 lock held by dhcpcd/5522:
 #0: ffffffff8f539288 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #0: ffffffff8f539288 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x3b0/0x18b0 net/ipv4/devinet.c:978
2 locks held by getty/5617:
 #0: ffff88814d40e0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000332e2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222
1 lock held by syz-executor/5856:
 #0: ffffffff8e13f9b8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:343 [inline]
 #0: ffffffff8e13f9b8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x3b9/0x730 kernel/rcu/tree_exp.h:957
3 locks held by kworker/u8:7/5979:
 #0: ffff88801a481148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3211 [inline]
 #0: ffff88801a481148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3319
 #1: ffffc90004e2fbc0 ((work_completion)(&map->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3212 [inline]
 #1: ffffc90004e2fbc0 ((work_completion)(&map->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3319
 #2: ffffffff8e13f880 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x4c/0x570 kernel/rcu/tree.c:3815
5 locks held by kworker/u8:8/5980:
3 locks held by kworker/u8:9/5990:
 #0: ffff88801a481148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3211 [inline]
 #0: ffff88801a481148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3319
 #1: ffffc90004e6fbc0 ((work_completion)(&map->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3212 [inline]
 #1: ffffc90004e6fbc0 ((work_completion)(&map->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3319
 #2: ffffffff8e13f9b8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:343 [inline]
 #2: ffffffff8e13f9b8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x3b9/0x730 kernel/rcu/tree_exp.h:957
2 locks held by syz.1.1242/10749:
 #0: ffffffff8f59e8b0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8e418648 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x137/0x1690 fs/nfsd/nfsctl.c:1919
2 locks held by syz.6.1246/10759:
 #0: ffffffff8f59e8b0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8e418648 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_version_get_doit+0x16e/0xb60 fs/nfsd/nfsctl.c:1844

=============================================

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:328 [inline]
 watchdog+0xf93/0xfe0 kernel/hung_task.c:491
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 5990 Comm: kworker/u8:9 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: wg-kex-wg1 wg_packet_handshake_send_worker
RIP: 0010:format_decode+0x3c5/0xe30 lib/vsprintf.c:2703
Code: 04 24 ff ff 48 89 e8 48 c1 e8 03 0f b6 04 10 84 c0 0f 85 9a 06 00 00 0f b6 5d 00 bf 2e 00 00 00 89 de e8 0e 88 49 f6 83 fb 2e <0f> 84 44 03 00 00 e8 00 85 49 f6 4c 8b 6c 24 08 48 ba 00 00 00 00
RSP: 0018:ffffc90004e6e4b0 EFLAGS: 00000212
RAX: ffffffff8b762942 RBX: 000000000000006c RCX: 0000000000000000
RDX: ffff88801cf50000 RSI: 000000000000006c RDI: 000000000000002e
RBP: ffffffff8b8b7ee3 R08: ffff88801cf50000 R09: 0000000000000002
R10: 0000000000000025 R11: 0000000000000000 R12: ffffc90004e6e55a
R13: 1ffff920009cdcab R14: 0000000000000005 R15: ffffffff8b8b7ee3
FS:  0000000000000000(0000) GS:ffff888125c18000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055c0b4cdfe28 CR3: 000000005bfdf000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 vsnprintf+0x102/0xf00 lib/vsprintf.c:2869
 sprintf+0xd9/0x120 lib/vsprintf.c:3089
 print_time kernel/printk/printk.c:1381 [inline]
 info_print_prefix+0x155/0x310 kernel/printk/printk.c:1407
 record_print_text+0x154/0x420 kernel/printk/printk.c:1456
 printk_get_next_message+0x26d/0x7b0 kernel/printk/printk.c:3024
 console_emit_next_record kernel/printk/printk.c:3092 [inline]
 console_flush_all+0x4ca/0xc40 kernel/printk/printk.c:3226
 __console_flush_and_unlock kernel/printk/printk.c:3285 [inline]
 console_unlock+0xc4/0x270 kernel/printk/printk.c:3325
 vprintk_emit+0x5b7/0x7a0 kernel/printk/printk.c:2450
 _printk+0xcf/0x120 kernel/printk/printk.c:2475
 ip_vs_schedule+0x1520/0x1c80 net/netfilter/ipvs/ip_vs_core.c:518
 udp_conn_schedule+0x332/0x710 net/netfilter/ipvs/ip_vs_proto_udp.c:78
 ip_vs_try_to_schedule net/netfilter/ipvs/ip_vs_core.c:1482 [inline]
 ip_vs_in_hook+0xc09/0x1be0 net/netfilter/ipvs/ip_vs_core.c:2054
 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
 nf_hook_slow+0xc5/0x220 net/netfilter/core.c:623
 nf_hook+0x217/0x380 include/linux/netfilter.h:273
 __ip_local_out+0x4db/0x600 net/ipv4/ip_output.c:118
 ip_local_out+0x26/0x70 net/ipv4/ip_output.c:127
 iptunnel_xmit+0x592/0xa40 net/ipv4/ip_tunnel_core.c:84
 udp_tunnel_xmit_skb+0x26e/0x3c0 net/ipv4/udp_tunnel_core.c:192
 send4+0x9c6/0xe20 drivers/net/wireguard/socket.c:85
 wg_socket_send_skb_to_peer+0xd1/0x1d0 drivers/net/wireguard/socket.c:175
 wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline]
 wg_packet_handshake_send_worker+0x1db/0x320 drivers/net/wireguard/send.c:51
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>