INFO: task syz-executor:5606 blocked for more than 143 seconds.
Tainted: G L Y syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor state:D stack:21856 pid:5606 tgid:5606 ppid:1 task_flags:0x400140 flags:0x00080002
Call Trace:
context_switch kernel/sched/core.c:5581 [inline]
__schedule+0x1b47/0x5b40 kernel/sched/core.c:7384
__schedule_loop kernel/sched/core.c:7461 [inline]
schedule+0x164/0x2b0 kernel/sched/core.c:7476
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7533
__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:1379
deactivate_locked_super+0xbe/0x110 fs/super.c:586
cleanup_mnt+0x3d3/0x460 fs/namespace.c:1329
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: 0033:0x7fd66439f397
RSP: 002b:00007ffef7578c98 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007fd6644344bb RCX: 00007fd66439f397
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffef7578d50
RBP: 00007ffef7578d50 R08: 00007ffef7579d50 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffef7579de0
R13: 00007fd6644344bb R14: 000000000002e519 R15: 00007ffef7579e20
Showing all locks held in the system:
locks held by khungtaskd/33: 1, last CPU#0:
#0: ffffffff8f15c520 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffffffff8f15c520 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffffffff8f15c520 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6871
locks held by getty/5365: 2, on CPU#1:
#0: ffff88803600c0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc9000322b2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360 drivers/tty/n_tty.c:2211
locks held by syz-executor/5606: 2, on CPU#0:
#0: ffff88802c51c0e8 (&type->s_umount_key#71){++++}-{4:4}, at: __super_lock fs/super.c:60 [inline]
#0: ffff88802c51c0e8 (&type->s_umount_key#71){++++}-{4:4}, at: __super_lock_excl fs/super.c:75 [inline]
#0: ffff88802c51c0e8 (&type->s_umount_key#71){++++}-{4:4}, at: deactivate_super+0xac/0xe0 fs/super.c:613
#1: ffffffff8f49fc80 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x4e/0xd0 fs/nfsd/nfssvc.c:590
locks held by kworker/1:4/5613: 3, on CPU#1:
#0: ffff88813fe0a148 ((wq_completion)events_freezable){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffff88813fe0a148 ((wq_completion)events_freezable){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffff88813fe0a148 ((wq_completion)events_freezable){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline]
#0: ffff88813fe0a148 ((wq_completion)events_freezable){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578
#1: ffffc90004497c40 ((work_completion)(&hcd->wakeup_work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffc90004497c40 ((work_completion)(&hcd->wakeup_work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffc90004497c40 ((work_completion)(&hcd->wakeup_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline]
#1: ffffc90004497c40 ((work_completion)(&hcd->wakeup_work)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578
#2: ffff88802a36f1d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#2: ffff88802a36f1d8 (&dev->mutex){....}-{4:4}, at: usb_remote_wakeup+0x23/0x120 drivers/usb/core/hub.c:3904
locks held by kworker/1:6/5707: 4, on CPU#1:
#0: ffff88801eea5d48 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#0: ffff88801eea5d48 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffff88801eea5d48 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline]
#0: ffff88801eea5d48 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578
#1: ffffc90004ecfc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffc90004ecfc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffc90004ecfc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3460 [inline]
#1: ffffc90004ecfc40 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_scheduled_works+0x97a/0x1630 kernel/workqueue.c:3578
#2: ffff88802a1f21d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#2: ffff88802a1f21d8 (&dev->mutex){....}-{4:4}, at: hub_event+0x184/0x4d30 drivers/usb/core/hub.c:5917
#3: ffff88801c284980 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_add_one+0x41/0x510 fs/kernfs/dir.c:833
locks held by syz.1.316/6722: 3, on CPU#0:
#0: ffff88807dc0b5f0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x118/0x160 fs/file.c:1408
#1: ffff888050866460 (sb_writers#17){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2753 [inline]
#1: ffff888050866460 (sb_writers#17){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0 fs/read_write.c:683
#2: ffffffff8f49fc80 (nfsd_mutex){+.+.}-{4:4}, at: write_ports+0xb5/0xd10 fs/nfsd/nfsctl.c:874
locks held by syz-executor/7022: 2, last CPU#1:
#0: ffff8880325b82e0 (&xt[i].mutex){+.+.}-{4:4}, at: xt_find_table_lock+0x55/0x400 net/netfilter/x_tables.c:1336
#1: ffffffff8f15c520 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffffffff8f15c520 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffffffff8f15c520 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1216 [inline]
#1: ffffffff8f15c520 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0x8f/0x2550 arch/x86/kernel/unwind_orc.c:495
locks held by syz.9.1135/9746: 3, on CPU#1:
#0: ffff8880797980f0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x118/0x160 fs/file.c:1408
#1: ffff88804bb02460 (sb_writers#17){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2753 [inline]
#1: ffff88804bb02460 (sb_writers#17){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0 fs/read_write.c:683
#2: ffffffff8f49fc80 (nfsd_mutex){+.+.}-{4:4}, at: write_ports+0xb5/0xd10 fs/nfsd/nfsctl.c:874
locks held by syz.9.1135/9751: 3, on CPU#1:
#0: ffff888079798ef0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x118/0x160 fs/file.c:1408
#1: ffff88804bb02460 (sb_writers#17){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2753 [inline]
#1: ffff88804bb02460 (sb_writers#17){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0 fs/read_write.c:683
#2: ffffffff8f49fc80 (nfsd_mutex){+.+.}-{4:4}, at: write_maxblksize+0x40c/0x630 fs/nfsd/nfsctl.c:922
locks held by syz.8.1545/11173: 1, on CPU#0:
#0: ffff88802c51c0e8 (&type->s_umount_key#71){++++}-{4:4}, at: __super_lock fs/super.c:62 [inline]
#0: ffff88802c51c0e8 (&type->s_umount_key#71){++++}-{4:4}, at: super_lock+0x2d1/0x3d0 fs/super.c:124
locks held by syz-executor/11496: 10, last CPU#1:
#0: ffff88807fe78460 (sb_writers#7){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2753 [inline]
#0: ffff88807fe78460 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0 fs/read_write.c:683
#1: ffff888079ac0080 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1d8/0x540 fs/kernfs/file.c:336
#2: ffff8880299890f8 (kn->active#51){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline]
#2: ffff8880299890f8 (kn->active#51){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x22b/0x540 fs/kernfs/file.c:337
#3: ffffffff8fee9460 (nsim_bus_dev_list_lock){+.+.}-{4:4}, at: del_device_store+0xd6/0x370 drivers/net/netdevsim/bus.c:233
#4: ffff888033829128 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1104 [inline]
#4: ffff888033829128 (&dev->mutex){....}-{4:4}, at: __device_driver_lock drivers/base/dd.c:1171 [inline]
#4: ffff888033829128 (&dev->mutex){....}-{4:4}, at: device_release_driver_internal+0xb9/0x880 drivers/base/dd.c:1369
#5: ffff888033828258 (&devlink->lock_key#3){+.+.}-{4:4}, at: nsim_drv_remove+0x50/0x170 drivers/net/netdevsim/dev.c:1724
#6: ffffffff90676ba0 (rtnl_mutex){+.+.}-{4:4}, at: nsim_destroy+0x173/0x800 drivers/net/netdevsim/netdev.c:1201
#7: ffff88801c284aa0 (&root->kernfs_supers_rwsem){++++}-{4:4}, at: kernfs_remove_by_name_ns+0x3f/0x140 fs/kernfs/dir.c:1790
#8: ffff88801c284980 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_remove_by_name_ns+0x4e/0x140 fs/kernfs/dir.c:1791
#9: ffff88801c284a10 (&root->kernfs_iattr_rwsem){++++}-{4:4}, at: kernfs_unlink_sibling+0x6d/0x240 fs/kernfs/dir.c:443
=============================================
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 33 Comm: khungtaskd Tainted: G L Y syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP, [Y]=FORCED_BIND
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 16 Comm: pr/ttyS0 Tainted: G L Y syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP, [Y]=FORCED_BIND
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:io_serial_in+0x77/0xc0 drivers/tty/serial/8250/8250_port.c:425
Code: e8 ce a5 46 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 df 72 b8 fc 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f c3 cc cc cc cc cc 44 89 f9 80 e1 07
RSP: 0018:ffffc900001578b8 EFLAGS: 00000002
RAX: 1ffffffff363d600 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: 0000000000000000 RDI: 0000000000000020
RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff85828b30 R12: dffffc0000000000
R13: 0000000000000000 R14: ffffffff9b1eb0c0 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff888124623000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4dc5ffbafc CR3: 0000000073f96000 CR4: 00000000003526f0
Call Trace:
serial_in drivers/tty/serial/8250/8250.h:134 [inline]
serial_lsr_in drivers/tty/serial/8250/8250.h:156 [inline]
wait_for_lsr+0x184/0x2f0 drivers/tty/serial/8250/8250_port.c:2027
serial8250_fifo_wait_for_lsr_thre drivers/tty/serial/8250/8250_port.c:3285 [inline]
__serial8250_console_fifo_write+0xcd/0x3e0 drivers/tty/serial/8250/8250_port.c:3360
serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3393 [inline]
__serial8250_console_write drivers/tty/serial/8250/8250_port.c:3444 [inline]
serial8250_console_write+0xaa1/0x1200 drivers/tty/serial/8250/8250_port.c:3508
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