INFO: task hung in tty_open

Status: upstream: reported on 2026/08/03 13:33
Reported-by: syzbot+7079ad18402f43113752@syzkaller.appspotmail.com
First crash: 9d06h, last: 7h25m
▶ ▼ Similar bugs (11)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 INFO: task hung in tty_open 1 6 1d04h 8d02h 0/3 upstream: reported on 2026/08/04 17:29
upstream INFO: task hung in tty_open serial 1 1 1773d 1773d 0/29 auto-closed as invalid on 2022/01/02 10:09
linux-4.14 INFO: task hung in tty_open (2) 1 1 1307d 1307d 0/1 upstream: reported on 2023/01/13 14:16
android-44 INFO: task hung in tty_open 1 syz, C 132 2462d 2678d 0/2 public: reported C repro on 2019/04/13 00:00
linux-6.6 INFO: task hung in tty_open 1 1 12d 12d 0/2 upstream: reported on 2026/07/31 15:41
upstream INFO: task hung in tty_open (2) serial 1 syz, C error error 19 1112d 1647d 0/29 auto-obsoleted due to no activity on 2023/11/04 13:34
linux-4.14 INFO: task hung in tty_open 1 2 2214d 2266d 0/1 auto-closed as invalid on 2020/11/17 06:29
android-414 INFO: task hung in tty_open 1 syz, C 152 2658d 2680d 0/1 public: reported C repro on 2019/04/11 00:00
upstream INFO: task can't die in show_free_areas serial 1 syz, C error error 285 2d12h 1661d 0/29 upstream: reported C repro on 2022/01/24 13:23
android-49 INFO: task hung in tty_open 1 syz, C 447 2443d 2679d 0/3 public: reported C repro on 2019/04/12 00:00
upstream INFO: task can't die in irqentry_exit (2) kernel 1 syz, C error 22 1652d 2068d 0/29 auto-obsoleted due to no activity on 2022/10/23 05:49

Sample crash report:
INFO: task syz.9.341:6462 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.9.341       state:D stack:27920 pid:6462  ppid:6111   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 schedule+0xb9/0x180 kernel/sched/core.c:6639
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6698
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x548/0xae0 kernel/locking/mutex.c:747
 tty_open_by_driver drivers/tty/tty_io.c:2045 [inline]
 tty_open+0x204/0xcb0 drivers/tty/tty_io.c:2128
 chrdev_open+0x585/0x5f0 fs/char_dev.c:414
 do_dentry_open+0x7dd/0x10b0 fs/open.c:882
 do_open fs/namei.c:3634 [inline]
 path_openat+0x2674/0x2f10 fs/namei.c:3791
 do_filp_open+0x1ee/0x420 fs/namei.c:3818
 do_sys_openat2+0x14b/0x4f0 fs/open.c:1320
 do_sys_open fs/open.c:1336 [inline]
 __do_sys_openat fs/open.c:1352 [inline]
 __se_sys_openat fs/open.c:1347 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1347
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f7ce155e90e
RSP: 002b:00007f7ce250ab28 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f7ce250b6c0 RCX: 00007f7ce155e90e
RDX: 0000000000000002 RSI: 00007f7ce250ac00 RDI: ffffffffffffff9c
RBP: 00007f7ce1635024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7ce1826038 R14: 00007f7ce1825fa0 R15: 00007ffeded46488
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8cb2e4f0 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8cb2ed10 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/28:
 #0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8cb2db60 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6527
2 locks held by getty/4032:
 #0: ffff88803039f098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41e/0x1360 drivers/tty/n_tty.c:2198
6 locks held by kworker/0:8/4610:
 #0: ffff88801e2d2d38 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #1: ffffc90004cafd00 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #2: ffff888027e6a190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:885 [inline]
 #2: ffff888027e6a190 (&dev->mutex){....}-{3:3}, at: hub_event+0x178/0x5200 drivers/usb/core/hub.c:5845
 #3: ffff88807b8a1190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:885 [inline]
 #3: ffff88807b8a1190 (&dev->mutex){....}-{3:3}, at: usb_disconnect+0xf8/0x8a0 drivers/usb/core/hub.c:2305
 #4: ffff888057d10118 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:885 [inline]
 #4: ffff888057d10118 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1099 [inline]
 #4: ffff888057d10118 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0xb1/0x7c0 drivers/base/dd.c:1302
 #5: ffffffff8dd5b968 (rtnl_mutex){+.+.}-{3:3}, at: unregister_netdev+0x6f/0x1c0 net/core/dev.c:11094
2 locks held by kworker/0:11/4613:
 #0: ffff888017470938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #1: ffffc90005077d00 ((work_completion)(&fw_work->work)){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
3 locks held by kworker/0:13/4615:
 #0: ffff888017470938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #1: ffffc90005247d00 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #2: ffff88803435f240 (&data->fib_lock){+.+.}-{3:3}, at: nsim_fib_event_work+0x283/0x3320 drivers/net/netdevsim/fib.c:1491
3 locks held by kworker/0:16/4618:
 #0: ffff88814cdb9538 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #1: ffffc90005277d00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #2: ffffffff8dd5b968 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xc4/0x1500 net/ipv6/addrconf.c:4138
4 locks held by kworker/0:18/4620:
 #0: ffff88801e2d2d38 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #1: ffffc90005287d00 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #2: ffff888145b36190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:885 [inline]
 #2: ffff888145b36190 (&dev->mutex){....}-{3:3}, at: hub_event+0x178/0x5200 drivers/usb/core/hub.c:5845
 #3: ffff888145b51500 (&port_dev->status_lock){+.+.}-{3:3}, at: usb_lock_port drivers/usb/core/hub.c:3200 [inline]
 #3: ffff888145b51500 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_event+0x61e/0x5200 drivers/usb/core/hub.c:5898
3 locks held by kworker/u4:12/6050:
3 locks held by syz.3.337/6399:
1 lock held by syz.9.341/6462:
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2045 [inline]
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x204/0xcb0 drivers/tty/tty_io.c:2128
1 lock held by syz.8.366/6591:
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2045 [inline]
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x204/0xcb0 drivers/tty/tty_io.c:2128
1 lock held by syz.7.499/7364:
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: ptmx_open+0xcc/0x2c0 drivers/tty/pty.c:823
2 locks held by udevd/7458:
1 lock held by syz.6.534/7580:
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2045 [inline]
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x204/0xcb0 drivers/tty/tty_io.c:2128
1 lock held by syz.2.539/7599:
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2045 [inline]
 #0: ffffffff8d290808 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x204/0xcb0 drivers/tty/tty_io.c:2128
1 lock held by udevd/7705:
 #0: ffff8880304bdaf0 (&type->i_mutex_dir_key#5){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:768 [inline]
 #0: ffff8880304bdaf0 (&type->i_mutex_dir_key#5){++++}-{3:3}, at: open_last_lookups fs/namei.c:3557 [inline]
 #0: ffff8880304bdaf0 (&type->i_mutex_dir_key#5){++++}-{3:3}, at: path_openat+0x7d9/0x2f10 fs/namei.c:3788
1 lock held by syz-executor/7771:
 #0: ffffffff8dd5b968 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
 #0: ffffffff8dd5b968 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x80d/0xfb0 net/core/rtnetlink.c:6163
2 locks held by syz.3.556/7785:
9 locks held by syz-executor/7790:
4 locks held by syz.9.558/7816:
 #0: ffffffff8dbc2a30 (minors_rwsem){+.+.}-{3:3}, at: hidraw_open+0x96/0x8b0 drivers/hid/hidraw.c:280
 #1: ffff888145b51500 (&port_dev->status_lock){+.+.}-{3:3}, at: usb_lock_port drivers/usb/core/hub.c:3200 [inline]
 #1: ffff888145b51500 (&port_dev->status_lock){+.+.}-{3:3}, at: usb_port_resume+0x26b/0x1c50 drivers/usb/core/hub.c:3758
 #2: ffff888145727068 (hcd->address0_mutex){+.+.}-{3:3}, at: usb_reset_and_verify_device+0x3b5/0x1620 drivers/usb/core/hub.c:6150
 #3: ffffffff8d6918b0 (ehci_cf_port_reset_rwsem){.+.+}-{3:3}, at: hub_port_reset+0x151/0x18d0 drivers/usb/core/hub.c:3057
1 lock held by sed/7830:

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

NMI backtrace for cpu 0
CPU: 0 PID: 28 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3e6/0x460 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
 watchdog+0xf0e/0xf50 kernel/hung_task.c:377
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/12 12:30 linux-6.1.y e4f7d8be268e f8d35649 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in tty_open
2026/08/10 11:19 linux-6.1.y e4f7d8be268e 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in tty_open
2026/08/07 06:26 linux-6.1.y 03f3a99e8e93 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in tty_open
2026/08/07 02:51 linux-6.1.y 03f3a99e8e93 c38879ea .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in tty_open
2026/08/05 21:36 linux-6.1.y fb28aa725e05 cd5b1963 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in tty_open
2026/08/03 13:32 linux-6.1.y fb28aa725e05 6b7c9f71 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in tty_open
* Struck through repros no longer work on HEAD.