INFO: task hung in tty_open

Status: upstream: reported on 2026/08/04 17:29
Reported-by: syzbot+522be398b7bc5889e97f@syzkaller.appspotmail.com
First crash: 56d, last: 3d21h
▶ ▼ Similar bugs (11)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in tty_open serial 1 1 1821d 1821d 0/29 auto-closed as invalid on 2022/01/02 10:09
linux-4.14 INFO: task hung in tty_open (2) 1 1 1355d 1355d 0/1 upstream: reported on 2023/01/13 14:16
android-44 INFO: task hung in tty_open 1 syz, C 132 2510d 2726d 0/2 public: reported C repro on 2019/04/13 00:00
linux-6.6 INFO: task hung in tty_open 1 2 17d 60d 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 1160d 1695d 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 2262d 2314d 0/1 auto-closed as invalid on 2020/11/17 06:29
android-414 INFO: task hung in tty_open 1 syz, C 152 2706d 2728d 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 303 22d 1709d 0/29 upstream: reported C repro on 2022/01/24 13:23
android-49 INFO: task hung in tty_open 1 syz, C 447 2491d 2727d 0/3 public: reported C repro on 2019/04/12 00:00
linux-6.1 INFO: task hung in tty_open 1 11 5d13h 57d 0/3 upstream: reported on 2026/08/03 13:33
upstream INFO: task can't die in irqentry_exit (2) kernel 1 syz, C error 22 1700d 2116d 0/29 auto-obsoleted due to no activity on 2022/10/23 05:49

Sample crash report:
INFO: task syz.6.1350:10570 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.1350      state:D stack:27888 pid:10570 ppid:  9173 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11c3/0x4350 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6537
 __mutex_lock_common+0xdf5/0x2400 kernel/locking/mutex.c:669
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 tty_open_by_driver drivers/tty/tty_io.c:2064 [inline]
 tty_open+0x20a/0xcd0 drivers/tty/tty_io.c:2148
 chrdev_open+0x585/0x5f0 fs/char_dev.c:414
 do_dentry_open+0x7f7/0xf90 fs/open.c:826
 do_open fs/namei.c:3659 [inline]
 path_openat+0x2718/0x2fb0 fs/namei.c:3793
 do_filp_open+0x1df/0x400 fs/namei.c:3820
 do_sys_openat2+0x14b/0x500 fs/open.c:1255
 do_sys_open fs/open.c:1271 [inline]
 __do_sys_openat fs/open.c:1287 [inline]
 __se_sys_openat fs/open.c:1282 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1282
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f52756d198e
RSP: 002b:00007f5273947b28 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f52739486c0 RCX: 00007f52756d198e
RDX: 0000000000000002 RSI: 00007f5273947c00 RDI: ffffffffffffff9c
RBP: 00007f52757a806b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5275999128 R14: 00007f5275999090 R15: 00007ffc9434bb08
 </TASK>
INFO: task syz.0.1365:10777 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.1365      state:D stack:27888 pid:10777 ppid:  4185 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11c3/0x4350 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6537
 __mutex_lock_common+0xdf5/0x2400 kernel/locking/mutex.c:669
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 tty_open_by_driver drivers/tty/tty_io.c:2064 [inline]
 tty_open+0x20a/0xcd0 drivers/tty/tty_io.c:2148
 chrdev_open+0x585/0x5f0 fs/char_dev.c:414
 do_dentry_open+0x7f7/0xf90 fs/open.c:826
 do_open fs/namei.c:3659 [inline]
 path_openat+0x2718/0x2fb0 fs/namei.c:3793
 do_filp_open+0x1df/0x400 fs/namei.c:3820
 do_sys_openat2+0x14b/0x500 fs/open.c:1255
 do_sys_open fs/open.c:1271 [inline]
 __do_sys_openat fs/open.c:1287 [inline]
 __se_sys_openat fs/open.c:1282 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1282
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fd16e36d98e
RSP: 002b:00007fd16c5e3b28 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fd16c5e46c0 RCX: 00007fd16e36d98e
RDX: 0000000000000002 RSI: 00007fd16c5e3c00 RDI: ffffffffffffff9c
RBP: 00007fd16e44406b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd16e635128 R14: 00007fd16e635090 R15: 00007fffc028d0b8
 </TASK>
INFO: task syz.4.1378:10910 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.1378      state:D stack:27280 pid:10910 ppid:  4187 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11c3/0x4350 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0xbd/0x2d0 kernel/time/timer.c:2093
 __down_common+0x289/0x3b0 kernel/locking/semaphore.c:228
 down+0x7e/0xd0 kernel/locking/semaphore.c:63
 console_lock+0x29/0x70 kernel/printk/printk.c:2557
 vcs_open+0x59/0xc0 drivers/tty/vt/vc_screen.c:763
 chrdev_open+0x585/0x5f0 fs/char_dev.c:414
 do_dentry_open+0x7f7/0xf90 fs/open.c:826
 do_open fs/namei.c:3659 [inline]
 path_openat+0x2718/0x2fb0 fs/namei.c:3793
 do_filp_open+0x1df/0x400 fs/namei.c:3820
 do_sys_openat2+0x14b/0x500 fs/open.c:1255
 do_sys_open fs/open.c:1271 [inline]
 __do_sys_openat fs/open.c:1287 [inline]
 __se_sys_openat fs/open.c:1282 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1282
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f593a31798e
RSP: 002b:00007f59385aeb28 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f59385af6c0 RCX: 00007f593a31798e
RDX: 0000000000000802 RSI: 00007f59385aec00 RDI: ffffffffffffff9c
RBP: 00007f59385aec00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: cccccccccccccccd
R13: 00007f593a5df038 R14: 00007f593a5defa0 R15: 00007ffc66549908
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
 #0: ffffffff8c31ef60 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by kworker/0:1H/151:
2 locks held by getty/3941:
 #0: ffff88802c108098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc900025e62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x594/0x1a50 drivers/tty/n_tty.c:2158
2 locks held by kworker/u4:16/7283:
3 locks held by syz.5.1344/10537:
1 lock held by syz.6.1350/10570:
 #0: ffffffff8c9f6768 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2064 [inline]
 #0: ffffffff8c9f6768 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x20a/0xcd0 drivers/tty/tty_io.c:2148
1 lock held by syz.0.1365/10777:
 #0: ffffffff8c9f6768 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2064 [inline]
 #0: ffffffff8c9f6768 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x20a/0xcd0 drivers/tty/tty_io.c:2148
1 lock held by syz.0.1689/13871:
 #0: ffffffff8c9f6768 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2064 [inline]
 #0: ffffffff8c9f6768 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x20a/0xcd0 drivers/tty/tty_io.c:2148
1 lock held by syz-executor/14150:

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

NMI backtrace for cpu 0
CPU: 0 PID: 27 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+0x188/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
 watchdog+0xe1b/0xe60 kernel/hung_task.c:369
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Crashes (18):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/25 23:56 linux-5.15.y 0248c33e835e f281d9d2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in tty_open
2026/09/11 19:33 linux-5.15.y 0996e0926f6b b6a5eeb7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in tty_open
2026/09/09 10:41 linux-5.15.y 0996e0926f6b 8387c273 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in tty_open
2026/09/04 20:08 linux-5.15.y 0996e0926f6b f65209a4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in tty_open
2026/09/01 16:57 linux-5.15.y 28c35638ec51 587f6b29 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in tty_open
2026/08/25 09:58 linux-5.15.y 945fa863f02c 614e416a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in tty_open
2026/08/22 14:01 linux-5.15.y 0eb903b5b519 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in tty_open
2026/08/17 18:44 linux-5.15.y aabd761612db 905244d6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in tty_open
2026/08/17 13:12 linux-5.15.y aabd761612db 905244d6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in tty_open
2026/08/14 17:04 linux-5.15.y aabd761612db 6f9b3e89 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in tty_open
2026/08/14 17:02 linux-5.15.y aabd761612db 6f9b3e89 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in tty_open
2026/08/14 09:33 linux-5.15.y aabd761612db b13552fe .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in tty_open
2026/08/11 15:27 linux-5.15.y aabd761612db 71790083 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in tty_open
2026/08/10 23:59 linux-5.15.y aabd761612db 508909ea .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in tty_open
2026/08/09 12:18 linux-5.15.y aabd761612db 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in tty_open
2026/08/06 00:03 linux-5.15.y 6e2fd6534337 cd5b1963 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in tty_open
2026/08/05 07:51 linux-5.15.y 6e2fd6534337 52aa2820 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in tty_open
2026/08/04 17:29 linux-5.15.y 6e2fd6534337 d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in tty_open
* Struck through repros no longer work on HEAD.