INFO: task syz-executor:25832 blocked for more than 143 seconds. Tainted: G U I L syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz-executor state:D stack:23496 pid:25832 tgid:25832 ppid:1 task_flags:0x400140 flags:0x00080002 Call Trace: context_switch kernel/sched/core.c:5298 [inline] __schedule+0xfee/0x6120 kernel/sched/core.c:6911 __schedule_loop kernel/sched/core.c:6993 [inline] schedule+0xdd/0x390 kernel/sched/core.c:7008 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7065 __mutex_lock_common kernel/locking/mutex.c:692 [inline] __mutex_lock+0xc9a/0x1b90 kernel/locking/mutex.c:776 nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576 nfsd_umount+0x3b/0x60 fs/nfsd/nfsctl.c:1364 deactivate_locked_super+0xc1/0x1b0 fs/super.c:476 deactivate_super fs/super.c:509 [inline] deactivate_super+0xe7/0x110 fs/super.c:505 cleanup_mnt+0x21f/0x450 fs/namespace.c:1312 task_work_run+0x150/0x240 kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:67 [inline] exit_to_user_mode_loop+0x100/0x4a0 kernel/entry/common.c:98 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline] do_syscall_64+0x668/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f59e439d9d7 RSP: 002b:00007fff7bed2fe8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 00007f59e4432050 RCX: 00007f59e439d9d7 RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fff7bed30a0 RBP: 00007fff7bed30a0 R08: 00007fff7bed40a0 R09: 00000000ffffffff R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff7bed4130 R13: 00007f59e4432050 R14: 000000000014dcbe R15: 00007fff7bed4170 Showing all locks held in the system: 3 locks held by kworker/1:1/29: #0: ffff88813fe63148 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x1310/0x19a0 kernel/workqueue.c:3251 #1: ffffc90000a47d08 ((fqdir_free_work).work){+.+.}-{0:0}, at: process_one_work+0x988/0x19a0 kernel/workqueue.c:3252 #2: ffffffff8e7f3200 (rcu_state.barrier_mutex){+.+.}-{4:4}, at: rcu_barrier+0x48/0x6d0 kernel/rcu/tree.c:3828 1 lock held by khungtaskd/31: #0: ffffffff8e7e7720 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline] #0: ffffffff8e7e7720 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline] #0: ffffffff8e7e7720 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775 4 locks held by kworker/u8:8/19702: #0: ffff88801c6ae948 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x1310/0x19a0 kernel/workqueue.c:3251 #1: ffffc90004b3fd08 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x988/0x19a0 kernel/workqueue.c:3252 #2: ffffffff905fca90 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xb8/0x920 net/core/net_namespace.c:675 #3: ffffffff8e7f3338 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x19e/0x3c0 kernel/rcu/tree_exp.h:343 2 locks held by syz.1.4344/25515: #0: ffffffff906c1610 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217 #1: ffffffff8ec585a8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x6c1/0xc00 fs/nfsd/nfsctl.c:1607 3 locks held by syz-executor/25820: 2 locks held by syz-executor/25825: #0: ffff88803b6100e0 (&type->s_umount_key#52){++++}-{4:4}, at: __super_lock fs/super.c:58 [inline] #0: ffff88803b6100e0 (&type->s_umount_key#52){++++}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline] #0: ffff88803b6100e0 (&type->s_umount_key#52){++++}-{4:4}, at: deactivate_super fs/super.c:508 [inline] #0: ffff88803b6100e0 (&type->s_umount_key#52){++++}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:505 #1: ffffffff8ec585a8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576 2 locks held by syz-executor/25832: #0: ffff888089d780e0 (&type->s_umount_key#52){++++}-{4:4}, at: __super_lock fs/super.c:58 [inline] #0: ffff888089d780e0 (&type->s_umount_key#52){++++}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline] #0: ffff888089d780e0 (&type->s_umount_key#52){++++}-{4:4}, at: deactivate_super fs/super.c:508 [inline] #0: ffff888089d780e0 (&type->s_umount_key#52){++++}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:505 #1: ffffffff8ec585a8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576 3 locks held by kworker/1:2/26005: #0: ffff88813fe63148 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x1310/0x19a0 kernel/workqueue.c:3251 #1: ffffc9000217fd08 (free_ipc_work){+.+.}-{0:0}, at: process_one_work+0x988/0x19a0 kernel/workqueue.c:3252 #2: ffffffff8e7f3338 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock+0x27f/0x3c0 kernel/rcu/tree_exp.h:311 2 locks held by syz.6.4583/26685: #0: ffff88807c3980e0 (&type->s_umount_key#52){++++}-{4:4}, at: __super_lock fs/super.c:58 [inline] #0: ffff88807c3980e0 (&type->s_umount_key#52){++++}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline] #0: ffff88807c3980e0 (&type->s_umount_key#52){++++}-{4:4}, at: deactivate_super fs/super.c:508 [inline] #0: ffff88807c3980e0 (&type->s_umount_key#52){++++}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:505 #1: ffffffff8ec585a8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576 2 locks held by syz-executor/30158: #0: ffff8880516f60e0 (&type->s_umount_key#52){++++}-{4:4}, at: __super_lock fs/super.c:58 [inline] #0: ffff8880516f60e0 (&type->s_umount_key#52){++++}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline] #0: ffff8880516f60e0 (&type->s_umount_key#52){++++}-{4:4}, at: deactivate_super fs/super.c:508 [inline] #0: ffff8880516f60e0 (&type->s_umount_key#52){++++}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:505 #1: ffffffff8ec585a8 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576 2 locks held by getty/31879: #0: ffff8880382710a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243 #1: ffffc90006c9d2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x1500 drivers/tty/n_tty.c:2211 4 locks held by syz.5.5806/32293: #0: ffff88806920cec0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close+0x26/0xb0 net/bluetooth/hci_core.c:500 #1: ffff88806920c0c0 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x35c/0x1240 net/bluetooth/hci_sync.c:5346 #2: ffffffff908adf88 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:2151 [inline] #2: ffffffff908adf88 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_hash_flush+0xbb/0x280 net/bluetooth/hci_conn.c:2644 #3: ffff88805b00d2f8 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x80/0x770 net/bluetooth/l2cap_core.c:1751 3 locks held by syz.9.5809/32304: #0: ffff8880775c4ec0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close+0x26/0xb0 net/bluetooth/hci_core.c:500 #1: ffff8880775c40c0 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x35c/0x1240 net/bluetooth/hci_sync.c:5346 #2: ffffffff908adf88 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:2151 [inline] #2: ffffffff908adf88 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_hash_flush+0xbb/0x280 net/bluetooth/hci_conn.c:2644 3 locks held by syz.6.5810/32307: #0: ffff8880371c0ec0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close+0x26/0xb0 net/bluetooth/hci_core.c:500 #1: ffff8880371c00c0 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x35c/0x1240 net/bluetooth/hci_sync.c:5346 #2: ffffffff908adf88 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:2151 [inline] #2: ffffffff908adf88 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_hash_flush+0xbb/0x280 net/bluetooth/hci_conn.c:2644 ============================================= NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 31 Comm: khungtaskd Tainted: G U I L syzkaller #0 PREEMPT(full) Tainted: [U]=USER, [I]=FIRMWARE_WORKAROUND, [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 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:113 nmi_trigger_cpumask_backtrace+0x1d7/0x230 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:161 [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:346 [inline] watchdog+0xd25/0x1050 kernel/hung_task.c:515 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158 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: 7750 Comm: kworker/u8:10 Tainted: G U I L syzkaller #0 PREEMPT(full) Tainted: [U]=USER, [I]=FIRMWARE_WORKAROUND, [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet RIP: 0010:validate_xmit_skb+0xab3/0x1590 net/core/dev.c:4038 Code: 80 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 0f b6 04 02 84 c0 74 06 0f 8e 6a 09 00 00 0f b6 ab 80 00 00 00 60 00 00 00 83 e5 60 89 ee e8 0e 1e a8 f8 40 80 fd 60 0f 84 06 RSP: 0018:ffffc900044df890 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffff88805b1303c0 RCX: ffffffff89600865 RDX: 1ffff1100b626088 RSI: ffffffff89600926 RDI: ffff88805b130440 RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff88805c204800 R13: 0000000000000000 R14: ffff88805b130444 R15: ffff88807cf6a000 FS: 0000000000000000(0000) GS:ffff888124346000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f7155347e20 CR3: 000000000e598000 CR4: 00000000003526f0 Call Trace: __dev_queue_xmit+0x1de8/0x4800 net/core/dev.c:4827 dev_queue_xmit include/linux/netdevice.h:3385 [inline] batadv_send_skb_packet+0x53e/0x6e0 net/batman-adv/send.c:100 batadv_iv_ogm_send_to_if net/batman-adv/bat_iv_ogm.c:391 [inline] batadv_iv_ogm_emit net/batman-adv/bat_iv_ogm.c:419 [inline] batadv_iv_send_outstanding_bat_ogm_packet+0x677/0x860 net/batman-adv/bat_iv_ogm.c:1700 process_one_work+0xa23/0x19a0 kernel/workqueue.c:3276 process_scheduled_works kernel/workqueue.c:3359 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3440 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245