INFO: task syz.2.188:6738 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.2.188 state:D stack:27560 pid:6738 tgid:6735 ppid:5623 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
__mutex_lock_common kernel/locking/mutex.c:726 [inline]
__mutex_lock+0xccc/0x1bd0 kernel/locking/mutex.c:821
nfsd_nl_version_set_doit+0xc4/0x7a0 fs/nfsd/nfsctl.c:1814
genl_family_rcv_msg_doit+0x214/0x300 net/netlink/genetlink.c:1114
genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
genl_rcv_msg+0x560/0x800 net/netlink/genetlink.c:1209
netlink_rcv_skb+0x159/0x420 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+0x585/0x850 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1900
sock_sendmsg_nosec net/socket.c:775 [inline]
__sock_sendmsg net/socket.c:790 [inline]
____sys_sendmsg+0xa4d/0xbe0 net/socket.c:2684
___sys_sendmsg+0x190/0x1e0 net/socket.c:2738
__sys_sendmsg+0x160/0x210 net/socket.c:2770
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x840 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9f34f9ce59
RSP: 002b:00007f9f35e23028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f9f35216180 RCX: 00007f9f34f9ce59
RDX: 0000000000004010 RSI: 00002000000004c0 RDI: 0000000000000008
RBP: 00007f9f35032e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9f35216218 R14: 00007f9f35216180 R15: 00007fff9a468ca8
INFO: task syz.0.201:6824 blocked for more than 144 seconds.
Tainted: G L syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.201 state:D stack:27560 pid:6824 tgid:6823 ppid:5626 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
__mutex_lock_common kernel/locking/mutex.c:726 [inline]
__mutex_lock+0xccc/0x1bd0 kernel/locking/mutex.c:821
nfsd_nl_svc_export_set_reqs_doit+0x8a/0x2f0 fs/nfsd/export.c:1057
genl_family_rcv_msg_doit+0x214/0x300 net/netlink/genetlink.c:1114
genl_family_rcv_msg net/netlink/genetlink.c:1194 [inline]
genl_rcv_msg+0x560/0x800 net/netlink/genetlink.c:1209
netlink_rcv_skb+0x159/0x420 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+0x585/0x850 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x8b0/0xda0 net/netlink/af_netlink.c:1900
sock_sendmsg_nosec net/socket.c:775 [inline]
__sock_sendmsg net/socket.c:790 [inline]
____sys_sendmsg+0xa4d/0xbe0 net/socket.c:2684
___sys_sendmsg+0x190/0x1e0 net/socket.c:2738
__sys_sendmsg+0x160/0x210 net/socket.c:2770
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x840 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f57ec39ce59
RSP: 002b:00007f57ed2d4028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f57ec615fa0 RCX: 00007f57ec39ce59
RDX: 00000000200040d0 RSI: 00002000000004c0 RDI: 0000000000000003
RBP: 00007f57ec432e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f57ec616038 R14: 00007f57ec615fa0 R15: 00007ffc3348c508
Showing all locks held in the system:
1 lock held by khungtaskd/31:
#0: ffffffff8e7e5ec0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#0: ffffffff8e7e5ec0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
#0: ffffffff8e7e5ec0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775
2 locks held by getty/5382:
#0: ffff888036d7f0a0 (&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
2 locks held by syz.3.177/6683:
#0: ffffffff906efe68 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
#1: ffffffff8ec6f080 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0xd5/0x1a80 fs/nfsd/nfsctl.c:1964
2 locks held by syz.2.188/6738:
#0: ffffffff906efe68 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
#1: ffffffff8ec6f080 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_version_set_doit+0xc4/0x7a0 fs/nfsd/nfsctl.c:1814
2 locks held by syz.0.201/6824:
#0: ffffffff906efe68 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
#1: ffffffff8ec6f080 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_svc_export_set_reqs_doit+0x8a/0x2f0 fs/nfsd/export.c:1057
2 locks held by syz-executor/6866:
#0: ffff88807808e0d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline]
#0: ffff88807808e0d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
#0: ffff88807808e0d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super fs/super.c:509 [inline]
#0: ffff88807808e0d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:506
#1: ffffffff8ec6f080 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
2 locks held by syz-executor/6966:
#0: ffff8880725a80d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline]
#0: ffff8880725a80d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
#0: ffff8880725a80d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super fs/super.c:509 [inline]
#0: ffff8880725a80d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:506
#1: ffffffff8ec6f080 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
2 locks held by syz-executor/7053:
#0: ffff88803345c0d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline]
#0: ffff88803345c0d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
#0: ffff88803345c0d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super fs/super.c:509 [inline]
#0: ffff88803345c0d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:506
#1: ffffffff8ec6f080 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
2 locks held by syz-executor/7590:
#0: ffff8880764300d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline]
#0: ffff8880764300d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
#0: ffff8880764300d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super fs/super.c:509 [inline]
#0: ffff8880764300d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:506
#1: ffffffff8ec6f080 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
2 locks held by syz-executor/8365:
#0: ffff88803ec620d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline]
#0: ffff88803ec620d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
#0: ffff88803ec620d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super fs/super.c:509 [inline]
#0: ffff88803ec620d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:506
#1: ffffffff8ec6f080 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
3 locks held by kworker/u10:10/8713:
#0: ffff88813feac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x12b1/0x1940 kernel/workqueue.c:3297
#1: ffffc90004e77d08 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x988/0x1940 kernel/workqueue.c:3298
#2: ffffffff906415c0 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0x51/0xc0 net/core/link_watch.c:313
3 locks held by kworker/u10:31/8734:
#0: ffff888032dc5140 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x12b1/0x1940 kernel/workqueue.c:3297
#1: ffffc90004a5fd08 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_one_work+0x988/0x1940 kernel/workqueue.c:3298
#2: ffffffff906415c0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
#2: ffffffff906415c0 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_verify_work+0x12/0x30 net/ipv6/addrconf.c:4769
2 locks held by syz.1.514/8778:
#0: ffffffff906efe68 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
#1: ffffffff8ec6f080 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x8c8/0x1100 fs/nfsd/nfsctl.c:1660
2 locks held by syz-executor/8881:
#0: ffff88803e43a0d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline]
#0: ffff88803e43a0d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
#0: ffff88803e43a0d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super fs/super.c:509 [inline]
#0: ffff88803e43a0d8 (&type->s_umount_key#54){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:506
#1: ffffffff8ec6f080 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
1 lock held by syz.9.562/9178:
#0: ffffffff906415c0 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:641 [inline]
#0: ffffffff906415c0 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x38/0x220 drivers/net/tun.c:3506
2 locks held by syz.3.574/9256:
#0: ffffffff906415c0 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:641 [inline]
#0: ffffffff906415c0 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x38/0x220 drivers/net/tun.c:3506
#1: ffffffff8e7f1968 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x27f/0x3c0 kernel/rcu/tree_exp.h:311
1 lock held by syz.0.575/9260:
#0: ffffffff906415c0 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:641 [inline]
#0: ffffffff906415c0 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x38/0x220 drivers/net/tun.c:3506
=============================================
NMI backtrace for cpu 0
CPU: 0 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 05/09/2026
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