INFO: task syz-executor:5617 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-executor state:D stack:22600 pid:5617 tgid:5617 ppid:1 task_flags:0x400140 flags:0
task:syz-executor state:D stack:22600 pid:5617 tgid:5617 ppid:1 task_flags:0x400140 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5527 [inline]
__schedule+0x17dd/0x5940 kernel/sched/core.c:7295
__schedule_loop kernel/sched/core.c:7372 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7387
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7444
__mutex_lock_common kernel/locking/mutex.c:726 [inline]
__mutex_lock+0x7c4/0x15a0 kernel/locking/mutex.c:821
nfsd_shutdown_threads+0x4e/0xd0 fs/nfsd/nfssvc.c:590
nfsd_umount+0x41/0x60 fs/nfsd/nfsctl.c:1374
deactivate_locked_super+0xbc/0x110 fs/super.c:589
cleanup_mnt+0x3d3/0x460 fs/namespace.c:1317
task_work_run+0x1d9/0x260 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:70 [inline]
exit_to_user_mode_loop+0x204/0x770 kernel/entry/common.c:101
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:343 [inline]
do_syscall_64+0x328/0x520 arch/x86/entry/syscall_64.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7058d9f397
RSP: 002b:00007ffd69fedec8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f7058e3448b RCX: 00007f7058d9f397
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffd69fedf80
RBP: 00007ffd69fedf80 R08: 00007ffd69feef80 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffd69fef010
R13: 00007f7058e3448b R14: 000000000005438e R15: 00007ffd69fef050
Showing all locks held in the system:
locks held by khungtaskd/33: 1, last CPU#0:
#0: ffffffff8ed5db60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffffffff8ed5db60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffffffff8ed5db60 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6871
locks held by kworker/u8:9/1166: 3, on CPU#1:
#0: ffff88801b0ac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffff88801b0ac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffff88801b0ac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3372 [inline]
#0: ffff88801b0ac140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3490
#1: ffffc900053e7c40 ((linkwatch_work).work){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffc900053e7c40 ((linkwatch_work).work){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffc900053e7c40 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3372 [inline]
#1: ffffc900053e7c40 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3490
#2: ffffffff902588e0 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:313
locks held by kworker/u8:10/3383: 3, last CPU#0:
#0: ffff888029538140 ((wq_completion)krds_cp_wq#5/0){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffff888029538140 ((wq_completion)krds_cp_wq#5/0){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffff888029538140 ((wq_completion)krds_cp_wq#5/0){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3372 [inline]
#0: ffff888029538140 ((wq_completion)krds_cp_wq#5/0){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3490
#1: ffffc9000e687c40 ((work_completion)(&(&cp->cp_conn_w)->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffc9000e687c40 ((work_completion)(&(&cp->cp_conn_w)->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffc9000e687c40 ((work_completion)(&(&cp->cp_conn_w)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3372 [inline]
#1: ffffc9000e687c40 ((work_completion)(&(&cp->cp_conn_w)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3490
#2: ffffffff8ed5db60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#2: ffffffff8ed5db60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#2: ffffffff8ed5db60 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1216 [inline]
#2: ffffffff8ed5db60 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0x8f/0x2550 arch/x86/kernel/unwind_orc.c:495
locks held by udevd/4987: 2, last CPU#0:
#0: ffffffff8f4f4c58 (tomoyo_ss){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:198 [inline]
#0: ffffffff8f4f4c58 (tomoyo_ss){.+.+}-{0:0}, at: srcu_read_lock include/linux/srcu.h:305 [inline]
#0: ffffffff8f4f4c58 (tomoyo_ss){.+.+}-{0:0}, at: tomoyo_read_lock security/tomoyo/common.h:1112 [inline]
#0: ffffffff8f4f4c58 (tomoyo_ss){.+.+}-{0:0}, at: tomoyo_check_open_permission+0x1d3/0x470 security/tomoyo/file.c:772
#1: ffffffff8ed5db60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffffff8ed5db60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffffff8ed5db60 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1216 [inline]
#1: ffffffff8ed5db60 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0x8f/0x2550 arch/x86/kernel/unwind_orc.c:495
locks held by getty/5376: 2, on CPU#1:
#0: ffff8880360260a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc900032332e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360 drivers/tty/n_tty.c:2211
locks held by syz-executor/5617: 2, on CPU#1:
#0: ffff88807f8e00e8 (&type->s_umount_key#94){+.+.}-{4:4}, at: __super_lock fs/super.c:60 [inline]
#0: ffff88807f8e00e8 (&type->s_umount_key#94){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:75 [inline]
#0: ffff88807f8e00e8 (&type->s_umount_key#94){+.+.}-{4:4}, at: deactivate_super+0xac/0xe0 fs/super.c:617
#1: ffffffff8f0a1c00 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x4e/0xd0 fs/nfsd/nfssvc.c:590
locks held by kworker/u9:5/5632: 3, on CPU#0:
#0: ffff888027a3e940 ((wq_completion)hci7){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffff888027a3e940 ((wq_completion)hci7){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffff888027a3e940 ((wq_completion)hci7){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3372 [inline]
#0: ffff888027a3e940 ((wq_completion)hci7){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3490
#1: ffffc900043bfc40 ((work_completion)(&hdev->power_on)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffc900043bfc40 ((work_completion)(&hdev->power_on)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffc900043bfc40 ((work_completion)(&hdev->power_on)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3372 [inline]
#1: ffffc900043bfc40 ((work_completion)(&hdev->power_on)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3490
#2: ffff888053d18ea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_open net/bluetooth/hci_core.c:429 [inline]
#2: ffff888053d18ea0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_power_on+0x1a2/0x750 net/bluetooth/hci_core.c:923
locks held by syz.4.1659/10558: 3, on CPU#0:
#0: ffff88801fff9b30 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320 fs/file.c:1259
#1: ffff888033a92460 (sb_writers#31){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2753 [inline]
#1: ffff888033a92460 (sb_writers#31){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0 fs/read_write.c:683
#2: ffffffff8f0a1c00 (nfsd_mutex){+.+.}-{4:4}, at: write_ports+0xb5/0xd10 fs/nfsd/nfsctl.c:869
locks held by kworker/0:1/12586: 5, on CPU#0:
#0: ffff888022ee2940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffff888022ee2940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffff888022ee2940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3372 [inline]
#0: ffff888022ee2940 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3490
#1: ffffc90002e1fc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffc90002e1fc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffc90002e1fc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3372 [inline]
#1: ffffc90002e1fc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3490
#2: ffff8880299d11d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#2: ffff8880299d11d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4d30 drivers/usb/core/hub.c:5912
#3: ffff888039e691d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#3: ffff888039e691d8 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x450 drivers/base/dd.c:1073
#4: ffff88802b3da1a0 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#4: ffff88802b3da1a0 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x450 drivers/base/dd.c:1073
locks held by syz-executor/12851: 1, last CPU#0:
#0: ffffffff8ed5db60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffffffff8ed5db60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffffffff8ed5db60 (rcu_read_lock){....}-{1:3}, at: page_ext_get+0x22/0x2e0 mm/page_ext.c:522
locks held by syz.3.2962/14958: 3, last CPU#0:
#0: ffff888053e6a0e8 (&type->s_umount_key#54/1){+.+.}-{4:4}, at: alloc_super fs/super.c:351 [inline]
#0: ffff888053e6a0e8 (&type->s_umount_key#54/1){+.+.}-{4:4}, at: sget_fc+0x977/0x1a40 fs/super.c:875
#1: ffff888026984350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xde/0xd70 block/bdev.c:990
#2: ffff888026985430 (&lo->lo_mutex){+.+.}-{4:4}, at: lo_open+0x4f/0xd0 drivers/block/loop.c:1744
locks held by syz.2.2967/14969: 1, last CPU#1:
#0: ffff88807e77b0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
locks held by syz.6.2965/14968: 2, on CPU#1:
#0: ffffffff902588e0 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:650 [inline]
#0: ffffffff902588e0 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0 drivers/net/tun.c:3587
#1: ffffffff8ed63f28 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:311 [inline]
#1: ffffffff8ed63f28 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2cb/0x760 kernel/rcu/tree_exp.h:966
=============================================
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 33 Comm: khungtaskd Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:123
nmi_trigger_cpumask_backtrace+0x17d/0x390 lib/nmi_backtrace.c:66
trigger_all_cpu_backtrace include/linux/nmi.h:164 [inline]
__sys_info lib/sys_info.c:157 [inline]
sys_info+0x135/0x170 lib/sys_info.c:165
check_hung_uninterruptible_tasks kernel/hung_task.c:377 [inline]
watchdog+0x1058/0x10d0 kernel/hung_task.c:598
kthread+0x38b/0x480 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 16 Comm: pr/ttyS0 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:io_serial_in+0x77/0xc0 drivers/tty/serial/8250/8250_port.c:409
Code: e8 5e b3 53 fc 44 89 f9 d3 e3 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 7f 32 c4 fc 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f e9 ca 77 77 06 cc 44 89 f9 80 e1 07
RSP: 0018:ffffc900001578b8 EFLAGS: 00000002
RAX: 1ffffffff35aa800 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: 0000000000000000 RDI: 0000000000000020
RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff857478d0 R12: dffffc0000000000
R13: 0000000000000000 R14: ffffffff9ad544e0 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff888124db7000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b34720ff8 CR3: 000000007588c000 CR4: 00000000003526f0
Call Trace:
serial_in drivers/tty/serial/8250/8250.h:128 [inline]
serial_lsr_in drivers/tty/serial/8250/8250.h:150 [inline]
wait_for_lsr+0x184/0x2f0 drivers/tty/serial/8250/8250_port.c:2013
serial8250_fifo_wait_for_lsr_thre drivers/tty/serial/8250/8250_port.c:3270 [inline]
__serial8250_console_fifo_write+0xcd/0x3e0 drivers/tty/serial/8250/8250_port.c:3345
serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3378 [inline]
__serial8250_console_write drivers/tty/serial/8250/8250_port.c:3429 [inline]
serial8250_console_write+0xaa1/0x1200 drivers/tty/serial/8250/8250_port.c:3493
nbcon_emit_next_record+0xef5/0x1a90 kernel/printk/nbcon.c:-1
nbcon_emit_one kernel/printk/nbcon.c:1157 [inline]
nbcon_kthread_func+0x6d9/0x8d0 kernel/printk/nbcon.c:1271
kthread+0x38b/0x480 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245