INFO: task syz.4.598:8252 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.598 state:D stack:27784 pid:8252 tgid:8250 ppid:5628 task_flags:0x400140 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5510 [inline]
__schedule+0x17d9/0x56c0 kernel/sched/core.c:7234
__schedule_loop kernel/sched/core.c:7311 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7326
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7383
__mutex_lock_common kernel/locking/mutex.c:726 [inline]
__mutex_lock+0x7bf/0x1550 kernel/locking/mutex.c:821
nfsd_nl_cache_flush_doit+0xe2/0x1b0 fs/nfsd/nfsctl.c:2236
genl_family_rcv_msg_doit+0x233/0x340 net/netlink/genetlink.c:1114
genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
genl_rcv_msg+0x614/0x7a0 net/netlink/genetlink.c:1209
netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2556
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x7bb/0x940 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900
sock_sendmsg_nosec+0x13a/0x180 net/socket.c:775
__sock_sendmsg net/socket.c:790 [inline]
____sys_sendmsg+0x54e/0x850 net/socket.c:2684
___sys_sendmsg+0x2a5/0x360 net/socket.c:2738
__sys_sendmsg net/socket.c:2770 [inline]
__do_sys_sendmsg net/socket.c:2775 [inline]
__se_sys_sendmsg net/socket.c:2773 [inline]
__x64_sys_sendmsg+0x1b1/0x290 net/socket.c:2773
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd46d59de99
RSP: 002b:00007fd46e4cb028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fd46d825fa0 RCX: 00007fd46d59de99
RDX: 0000000004000080 RSI: 0000200000000100 RDI: 0000000000000003
RBP: 00007fd46d633eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd46d826038 R14: 00007fd46d825fa0 R15: 00007ffe16b7ab38
Showing all locks held in the system:
1 lock held by khungtaskd/31:
#0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
#0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
1 lock held by udevd/4987:
#0: ffff8880b863b160 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2d/0x160 kernel/sched/core.c:667
2 locks held by getty/5373:
#0: ffff8880361080a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc900032332e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360 drivers/tty/n_tty.c:2211
2 locks held by kworker/u9:2/5620:
#0: ffff888027b25940 ((wq_completion)nbd1-recv){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
#0: ffff888027b25940 ((wq_completion)nbd1-recv){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
#1: ffffc90003dcfc40 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
#1: ffffc90003dcfc40 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
2 locks held by kworker/u9:3/5625:
#0: ffff888027c12940 ((wq_completion)nbd2-recv){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
#0: ffff888027c12940 ((wq_completion)nbd2-recv){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
#1: ffffc90003defc40 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
#1: ffffc90003defc40 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
2 locks held by kworker/u9:4/5626:
#0: ffff888027c74940 ((wq_completion)nbd4-recv){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
#0: ffff888027c74940 ((wq_completion)nbd4-recv){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
#1: ffffc9000426fc40 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
#1: ffffc9000426fc40 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
3 locks held by kworker/0:3/5632:
#0: ffff88801b02b140 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
#0: ffff88801b02b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
#1: ffffc9000429fc40 (xfrm_state_gc_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
#1: ffffc9000429fc40 (xfrm_state_gc_work){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
#2: ffffffff8eb5ff68 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:343 [inline]
#2: ffffffff8eb5ff68 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x38d/0x770 kernel/rcu/tree_exp.h:961
2 locks held by kworker/u9:9/5639:
#0: ffff888027c17940 ((wq_completion)nbd3-recv){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
#0: ffff888027c17940 ((wq_completion)nbd3-recv){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
#1: ffffc9000430fc40 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
#1: ffffc9000430fc40 ((work_completion)(&args->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
2 locks held by syz.3.402/7630:
#0: ffffffff9009d8a8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
#1: ffffffff8ee8e5e0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x135/0x1750 fs/nfsd/nfsctl.c:1964
2 locks held by syz.4.598/8252:
#0: ffffffff9009d8a8 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
#1: ffffffff8ee8e5e0 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_cache_flush_doit+0xe2/0x1b0 fs/nfsd/nfsctl.c:2236
1 lock held by syz.1.2662/14104:
#0: ffffffff9002d040 (rtnl_mutex){+.+.}-{4:4}, at: ppp_release+0xa6/0x140 drivers/net/ppp/ppp_generic.c:414
2 locks held by syz.5.2663/14106:
#0: ffffffff9002d040 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:641 [inline]
#0: ffffffff9002d040 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0 drivers/net/tun.c:3510
#1: ffffffff8eb5ff68 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:311 [inline]
#1: ffffffff8eb5ff68 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2d0/0x770 kernel/rcu/tree_exp.h:961
=============================================
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026
Call Trace:
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:122
nmi_trigger_cpumask_backtrace+0x17a/0x380 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+0x135/0x170 lib/sys_info.c:165
check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
watchdog+0xfd7/0x1030 kernel/hung_task.c:561
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:64
Code: fc 7f 02 e9 13 05 03 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d d3 aa 19 00 fb f4 cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90
RSP: 0018:ffffc90000197e40 EFLAGS: 00000242
RAX: 00000000000d9507 RBX: ffffffff819ab450 RCX: 0000000080000001
RDX: 0000000000000001 RSI: ffffffff8e22d19b RDI: ffffffff8c4bda80
RBP: ffffc90000197f10 R08: ffff8880b87338db R09: 1ffff110170e671b
R10: dffffc0000000000 R11: ffffed10170e671c R12: 0000000000000000
R13: 1ffff11003bdf000 R14: 1ffff92000032fd0 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff888125058000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007effbafef4b8 CR3: 0000000066d8c000 CR4: 00000000003526f0
Call Trace:
arch_safe_halt arch/x86/kernel/process.c:767 [inline]
default_idle+0x9/0x20 arch/x86/kernel/process.c:768
default_idle_call+0x72/0xb0 kernel/sched/idle.c:122
cpuidle_idle_call kernel/sched/idle.c:199 [inline]
do_idle+0x2e0/0x540 kernel/sched/idle.c:355
cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:454
start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:312
common_startup_64+0x13e/0x157