INFO: task syz.2.11101:29922 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.11101 state:D stack:25128 pid:29922 tgid:29922 ppid:5818 task_flags:0x400040 flags:0x00080003
Call Trace:
context_switch kernel/sched/core.c:5325 [inline]
__schedule+0x16f3/0x4c20 kernel/sched/core.c:6929
__schedule_loop kernel/sched/core.c:7011 [inline]
rt_mutex_schedule+0x77/0xf0 kernel/sched/core.c:7307
rt_mutex_slowlock_block+0x5ba/0x6d0 kernel/locking/rtmutex.c:1647
__rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline]
__rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1760 [inline]
rt_mutex_slowlock+0x2b1/0x6e0 kernel/locking/rtmutex.c:1800
__rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline]
__mutex_lock_common kernel/locking/rtmutex_api.c:536 [inline]
mutex_lock_nested+0x16a/0x1d0 kernel/locking/rtmutex_api.c:547
nfsd_shutdown_threads+0x4e/0xd0 fs/nfsd/nfssvc.c:596
nfsd_umount+0x42/0xd0 fs/nfsd/nfsctl.c:1386
deactivate_locked_super+0xbc/0x130 fs/super.c:474
cleanup_mnt+0x425/0x4c0 fs/namespace.c:1318
task_work_run+0x1d1/0x260 kernel/task_work.c:227
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop+0xe9/0x110 kernel/entry/common.c:43
exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9bc234eec9
RSP: 002b:00007ffd9d628dc8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f9bc25a7da0 RCX: 00007f9bc234eec9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f9bc25a7da0 R08: 00000000000094ec R09: 000000079d6290bf
R10: 00000000005f5f7c R11: 0000000000000246 R12: 00000000000cea24
R13: 00007f9bc25a5fa0 R14: ffffffffffffffff R15: 00007ffd9d628ee0
Showing all locks held in the system:
1 lock held by khungtaskd/38:
#0: ffffffff8d3a9a40 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#0: ffffffff8d3a9a40 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
#0: ffffffff8d3a9a40 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by getty/5575:
#0: ffff88823bf228a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc90003e7e2e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x444/0x1400 drivers/tty/n_tty.c:2222
3 locks held by kworker/u8:45/21856:
#0: ffff88801a2ec138 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3238 [inline]
#0: ffff88801a2ec138 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3346
#1: ffffc9000aebfbc0 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3239 [inline]
#1: ffffc9000aebfbc0 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3346
#2: ffffffff8e64e640 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf7/0x820 net/core/net_namespace.c:669
2 locks held by syz.8.10030/27485:
#0: ffffffff8e6c1780 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
#1: ffffffff8d683498 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0x134/0x1660 fs/nfsd/nfsctl.c:1919
2 locks held by syz.2.11101/29922:
#0: ffff888028b220d0 (&type->s_umount_key#94){+.+.}-{4:4}, at: __super_lock fs/super.c:57 [inline]
#0: ffff888028b220d0 (&type->s_umount_key#94){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
#0: ffff888028b220d0 (&type->s_umount_key#94){+.+.}-{4:4}, at: deactivate_super+0xa9/0xe0 fs/super.c:506
#1: ffffffff8d683498 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x4e/0xd0 fs/nfsd/nfssvc.c:596
4 locks held by kworker/u8:0/30678:
1 lock held by syz.5.12484/785:
1 lock held by syz.7.12488/786:
1 lock held by syz.0.12482/788:
#0: ffffffff8e65b578 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
#0: ffffffff8e65b578 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
#0: ffffffff8e65b578 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_dellink+0x331/0x710 net/core/rtnetlink.c:3547
=============================================
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 38 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
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+0x439/0x7d0 arch/x86/kernel/process.c:148
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: 785 Comm: syz.5.12484 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:__this_cpu_preempt_check+0x0/0x20 lib/smp_processor_id.c:63
Code: d6 2d 7c f6 eb a7 e8 9f e4 ff ff 66 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1e fa 48 89 fe 48 c7 c7 e0 96 1d 8b e9 bd fe ff ff cc cc cc
RSP: 0018:ffffc9000bedecb8 EFLAGS: 00000046
RAX: ffff888048ff1e00 RBX: 0000000000000000 RCX: 8608aee3be8be200
RDX: 0000000000000000 RSI: ffffffff8ab96997 RDI: ffffffff8cbad8e8
RBP: ffffffff8ab8350a R08: 0000000000000001 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1d6b7e7 R12: 0000000000000000
R13: ffff8880b883cae0 R14: 0000000000000001 R15: 0000000000000046
FS: 00007f5d59c5e6c0(0000) GS:ffff888127022000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000013038 CR3: 000000006db50000 CR4: 00000000003526f0
DR0: ffffffffffffffff DR1: 00000000000001f8 DR2: 0000000000000083
DR3: ffffffffefffff15 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
lockdep_recursion_inc kernel/locking/lockdep.c:465 [inline]
lock_acquire+0xe7/0x360 kernel/locking/lockdep.c:5867
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162
rtlock_slowlock kernel/locking/rtmutex.c:1894 [inline]
rtlock_lock kernel/locking/spinlock_rt.c:43 [inline]
__rt_spin_lock kernel/locking/spinlock_rt.c:49 [inline]
rt_spin_lock+0x14a/0x3e0 kernel/locking/spinlock_rt.c:57
spin_lock_irq include/linux/spinlock_rt.h:93 [inline]
backlog_lock_irq_disable net/core/dev.c:243 [inline]
process_backlog+0x50f/0x900 net/core/dev.c:6467
__napi_poll+0xb6/0x540 net/core/dev.c:7506
napi_poll net/core/dev.c:7569 [inline]
net_rx_action+0x707/0xe00 net/core/dev.c:7696
handle_softirqs+0x22f/0x710 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
__local_bh_enable_ip+0x1a0/0x2e0 kernel/softirq.c:302
local_bh_enable include/linux/bottom_half.h:33 [inline]
netif_rx net/core/dev.c:5559 [inline]
dev_loopback_xmit+0x354/0x4e0 net/core/dev.c:4236
NF_HOOK include/linux/netfilter.h:318 [inline]
ip_mc_output+0x25c/0x590 net/ipv4/ip_output.c:399
ip_local_out net/ipv4/ip_output.c:129 [inline]
ip_send_skb+0x74/0x100 net/ipv4/ip_output.c:1506
udp_send_skb+0xaf1/0x14c0 net/ipv4/udp.c:1195
udp_sendmsg+0x195a/0x2170 net/ipv4/udp.c:1484
sock_sendmsg_nosec net/socket.c:714 [inline]
__sock_sendmsg+0x19c/0x270 net/socket.c:729
____sys_sendmsg+0x534/0x820 net/socket.c:2617
___sys_sendmsg+0x21f/0x2a0 net/socket.c:2671
__sys_sendmmsg+0x22d/0x430 net/socket.c:2760
__do_sys_sendmmsg net/socket.c:2787 [inline]
__se_sys_sendmmsg net/socket.c:2784 [inline]
__x64_sys_sendmmsg+0xa0/0xc0 net/socket.c:2784
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: 0033:0x7f5d5b9feec9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 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:00007f5d59c5e038 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f5d5bc55fa0 RCX: 00007f5d5b9feec9
RDX: 000000000800001d RSI: 0000200000007fc0 RDI: 0000000000000003
RBP: 00007f5d5ba81f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5d5bc56038 R14: 00007f5d5bc55fa0 R15: 00007fff94829d18