syzbot

INFO: task syz.4.4557:32226 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.4.4557      state:D stack:27976 pid:32226 tgid:32223 ppid:23830  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 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_get_doit+0x18a/0x800 fs/nfsd/nfsctl.c:1805
 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: 0033:0x7f61f898efc9
RSP: 002b:00007f61f6bd5038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f61f8be6090 RCX: 00007f61f898efc9
RDX: 00000000200008e4 RSI: 0000200000000280 RDI: 0000000000000003
RBP: 00007f61f8a11f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f61f8be6128 R14: 00007f61f8be6090 R15: 00007ffdac3bd828
 </TASK>
INFO: task syz.0.4569:32277 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.0.4569      state:D stack:25768 pid:32277 tgid:32276 ppid:22215  task_flags:0x400140 flags:0x00080006
Call Trace:
 <TASK>
 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:1327
 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: 0033:0x7f874a58efc9
RSP: 002b:00007f874b470038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: fffffffffffffffe RBX: 00007f874a7e5fa0 RCX: 00007f874a58efc9
RDX: 0000200000000080 RSI: 0000200000000040 RDI: 0000000000000000
RBP: 00007f874a611f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000017 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f874a7e6038 R14: 00007f874a7e5fa0 R15: 00007ffd1eef1438
 </TASK>
INFO: task syz.3.4596:32379 blocked for more than 145 seconds.
      Tainted: G     U  W    L XTNJ syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.4596      state:D stack:27688 pid:32379 tgid:32378 ppid:21603  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 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:1327
 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: 0033:0x7fadee58efc9
RSP: 002b:00007fadef47d038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: fffffffffffffffe RBX: 00007fadee7e5fa0 RCX: 00007fadee58efc9
RDX: 0000200000000140 RSI: 0000200000000100 RDI: 0000000000000000
RBP: 00007fadee611f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000010001 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fadee7e6038 R14: 00007fadee7e5fa0 R15: 00007fff592c76c8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8e3c42e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e3c42e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #0: ffffffff8e3c42e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x36/0x1c0 kernel/locking/lockdep.c:6775
5 locks held by kworker/u8:23/11785:
 #0: ffff88801ba9f148 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3238
 #1: ffffc9000ea47d00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3239
 #2: ffffffff900e6b30 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xad/0x8b0 net/core/net_namespace.c:669
 #3: ffffffff900fcf48 (rtnl_mutex){+.+.}-{4:4}, at: default_device_exit_batch+0x8b/0xaf0 net/core/dev.c:12837
 #4: ffffffff8e3cf878 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x1a3/0x3c0 kernel/rcu/tree_exp.h:343
4 locks held by kworker/1:4/12849:
2 locks held by getty/14444:
 #0: ffff88814e0a30a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc90003de52f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x41b/0x14f0 drivers/tty/n_tty.c:2222
1 lock held by syz.1.2685/23561:
2 locks held by kworker/u8:43/28506:
 #0: ffff888020f19948 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3238
 #1: ffffc900039afd00 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3239
2 locks held by syz.4.4557/32224:
 #0: ffffffff901a0b10 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8e7ece88 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x687/0xbc0 fs/nfsd/nfsctl.c:1590
2 locks held by syz.4.4557/32226:
 #0: ffffffff901a0b10 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8e7ece88 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_version_get_doit+0x18a/0x800 fs/nfsd/nfsctl.c:1805
2 locks held by syz.0.4569/32277:
 #0: ffff888058a7e0e0 (&type->s_umount_key#50){++++}-{4:4}, at: __super_lock fs/super.c:57 [inline]
 #0: ffff888058a7e0e0 (&type->s_umount_key#50){++++}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
 #0: ffff888058a7e0e0 (&type->s_umount_key#50){++++}-{4:4}, at: deactivate_super fs/super.c:505 [inline]
 #0: ffff888058a7e0e0 (&type->s_umount_key#50){++++}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:502
 #1: ffffffff8e7ece88 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:593
2 locks held by syz.3.4596/32379:
 #0: ffff888022f600e0 (&type->s_umount_key#50){++++}-{4:4}, at: __super_lock fs/super.c:57 [inline]
 #0: ffff888022f600e0 (&type->s_umount_key#50){++++}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
 #0: ffff888022f600e0 (&type->s_umount_key#50){++++}-{4:4}, at: deactivate_super fs/super.c:505 [inline]
 #0: ffff888022f600e0 (&type->s_umount_key#50){++++}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:502
 #1: ffffffff8e7ece88 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:593
2 locks held by syz-executor/32462:
 #0: ffff888064aac0e0 (&type->s_umount_key#50){++++}-{4:4}, at: __super_lock fs/super.c:57 [inline]
 #0: ffff888064aac0e0 (&type->s_umount_key#50){++++}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
 #0: ffff888064aac0e0 (&type->s_umount_key#50){++++}-{4:4}, at: deactivate_super fs/super.c:505 [inline]
 #0: ffff888064aac0e0 (&type->s_umount_key#50){++++}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:502
 #1: ffffffff8e7ece88 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:593
2 locks held by syz.2.5080/2433:
 #0: ffffffff901a0b10 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8e7ece88 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_get_doit+0x1c6/0x7c0 fs/nfsd/nfsctl.c:1672
1 lock held by syz.6.5106/2559:
 #0: ffffffff900fcf48 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:634 [inline]
 #0: ffffffff900fcf48 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x38/0x230 drivers/net/tun.c:3436
4 locks held by syz.8.5107/2553:
 #0: ffff8880352f4dc8 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close+0x26/0x90 net/bluetooth/hci_core.c:499
 #1: ffff8880352f40b8 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x3ae/0x11d0 net/bluetooth/hci_sync.c:5291
 #2: ffffffff9036f9c8 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:2118 [inline]
 #2: ffffffff9036f9c8 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_hash_flush+0xbb/0x260 net/bluetooth/hci_conn.c:2602
 #3: ffff88801d778338 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x80/0x730 net/bluetooth/l2cap_core.c:1762
2 locks held by syz.7.5109/2567:
 #0: ffff888024ed60e0 (&type->s_umount_key#50){++++}-{4:4}, at: __super_lock fs/super.c:57 [inline]
 #0: ffff888024ed60e0 (&type->s_umount_key#50){++++}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
 #0: ffff888024ed60e0 (&type->s_umount_key#50){++++}-{4:4}, at: deactivate_super fs/super.c:505 [inline]
 #0: ffff888024ed60e0 (&type->s_umount_key#50){++++}-{4:4}, at: deactivate_super+0xd6/0x100 fs/super.c:502
 #1: ffffffff8e7ece88 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:593

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

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 10/02/2025
Call Trace:
 <TASK>
 __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
 </TASK>