INFO: task syz-executor:5827 blocked for more than 143 seconds.
Tainted: G U W L XTNJ syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor state:D stack:23400 pid:5827 tgid:5827 ppid:1 task_flags:0x400140 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5325 [inline]
__schedule+0x1190/0x5de0 kernel/sched/core.c:6929
__schedule_loop kernel/sched/core.c:7011 [inline]
schedule+0xe7/0x3a0 kernel/sched/core.c:7026
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7083
__mutex_lock_common kernel/locking/mutex.c:676 [inline]
__mutex_lock+0x818/0x1060 kernel/locking/mutex.c:760
nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:593
nfsd_umount+0x48/0xe0 fs/nfsd/nfsctl.c:1347
deactivate_locked_super+0xc1/0x1a0 fs/super.c:473
deactivate_super fs/super.c:506 [inline]
deactivate_super+0xde/0x100 fs/super.c:502
cleanup_mnt+0x225/0x450 fs/namespace.c:1318
task_work_run+0x150/0x240 kernel/task_work.c:227
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop+0xec/0x130 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+0x426/0xfa0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f86b1990a77
RSP: 002b:00007fffc920be08 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f86b1a13d7d RCX: 00007f86b1990a77
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fffc920bec0
RBP: 00007fffc920bec0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007fffc920cf50
R13: 00007f86b1a13d7d R14: 0000000000051d01 R15: 00007fffc920cf90
INFO: task syz.3.920:10078 blocked for more than 144 seconds.
Tainted: G U W L XTNJ syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.920 state:D stack:27672 pid:10078 tgid:10077 ppid:5837 task_flags:0x400140 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5325 [inline]
__schedule+0x1190/0x5de0 kernel/sched/core.c:6929
__schedule_loop kernel/sched/core.c:7011 [inline]
schedule+0xe7/0x3a0 kernel/sched/core.c:7026
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7083
__mutex_lock_common kernel/locking/mutex.c:676 [inline]
__mutex_lock+0x818/0x1060 kernel/locking/mutex.c:760
nfsd_nl_version_set_doit+0xc4/0x7a0 fs/nfsd/nfsctl.c:1730
genl_family_rcv_msg_doit+0x209/0x2f0 net/netlink/genetlink.c:1115
genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
genl_rcv_msg+0x55c/0x800 net/netlink/genetlink.c:1210
netlink_rcv_skb+0x158/0x420 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+0x5aa/0x870 net/netlink/af_netlink.c:1346
netlink_sendmsg+0x8c8/0xdd0 net/netlink/af_netlink.c:1896
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg net/socket.c:742 [inline]
____sys_sendmsg+0xa98/0xc70 net/socket.c:2630
___sys_sendmsg+0x134/0x1d0 net/socket.c:2684
__sys_sendmsg+0x16d/0x220 net/socket.c:2716
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff678b8f749
RSP: 002b:00007ff679a94038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007ff678de5fa0 RCX: 00007ff678b8f749
RDX: 0000000000000844 RSI: 00002000000004c0 RDI: 0000000000000003
RBP: 00007ff678c13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff678de6038 R14: 00007ff678de5fa0 R15: 00007ffe8217a2f8
Showing all locks held in the system:
3 locks held by kworker/u8:0/12:
#0: ffff88813ff29948 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3238
#1: ffffc90000117d00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3239
#2: ffffffff900eb2c8 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0x51/0xc0 net/core/link_watch.c:303
1 lock held by khungtaskd/31:
#0: ffffffff8e3c45e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#0: ffffffff8e3c45e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
#0: ffffffff8e3c45e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6775
2 locks held by syz-executor/5827:
#0: ffff88803073e0e0 (&type->s_umount_key#52){++++}-{4:4}, at: __super_lock fs/super.c:57 [inline]
#0: ffff88803073e0e0 (&type->s_umount_key#52){++++}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
#0: ffff88803073e0e0 (&type->s_umount_key#52){++++}-{4:4}, at: deactivate_super fs/super.c:505 [inline]
#0: ffff88803073e0e0 (&type->s_umount_key#52){++++}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:502
#1: ffffffff8e7ed348 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:593
2 locks held by syz.0.872/9869:
#0: ffffffff9018f090 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
#1: ffffffff8e7ed348 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x687/0xbc0 fs/nfsd/nfsctl.c:1590
2 locks held by syz.3.920/10078:
#0: ffffffff9018f090 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
#1: ffffffff8e7ed348 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_version_set_doit+0xc4/0x7a0 fs/nfsd/nfsctl.c:1730
2 locks held by syz.7.1104/10982:
#0: ffffffff9018f090 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
#1: ffffffff8e7ed348 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0xd5/0x1b10 fs/nfsd/nfsctl.c:1880
2 locks held by syz.6.1152/11191:
#0: ffffffff9018f090 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
#1: ffffffff8e7ed348 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x687/0xbc0 fs/nfsd/nfsctl.c:1590
2 locks held by syz-executor/11204:
#0: ffff8880320900e0 (&type->s_umount_key#52){++++}-{4:4}, at: __super_lock fs/super.c:57 [inline]
#0: ffff8880320900e0 (&type->s_umount_key#52){++++}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
#0: ffff8880320900e0 (&type->s_umount_key#52){++++}-{4:4}, at: deactivate_super fs/super.c:505 [inline]
#0: ffff8880320900e0 (&type->s_umount_key#52){++++}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:502
#1: ffffffff8e7ed348 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:593
2 locks held by syz.9.1398/12313:
2 locks held by syz.5.1420/12396:
#0: ffffffff900eb2c8 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:634 [inline]
#0: ffffffff900eb2c8 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x38/0x230 drivers/net/tun.c:3436
#1: ffffffff8e3cfb78 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x284/0x3c0 kernel/rcu/tree_exp.h:311
=============================================
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Tainted: G U W L XTNJ syzkaller #0 PREEMPT(full)
Tainted: [U]=USER, [W]=WARN, [L]=SOFTLOCKUP, [X]=AUX, [T]=RANDSTRUCT, [N]=TEST, [J]=FWCTL
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
nmi_cpu_backtrace+0x27b/0x390 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x29c/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:332 [inline]
watchdog+0xf3f/0x1170 kernel/hung_task.c:495
kthread+0x3c5/0x780 kernel/kthread.c:463
ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245