INFO: task hung in vt_ioctl

Status: upstream: reported on 2026/08/11 00:02
Reported-by: syzbot+3e4cfd6db5f42b0e1a62@syzkaller.appspotmail.com
First crash: 54d, last: 2d15h
▶ ▼ Similar bugs (11)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in vt_ioctl (7) prio:high kernel 1 2 171d 175d 0/29 auto-obsoleted due to no activity on 2026/07/14 12:03
linux-6.6 INFO: task hung in vt_ioctl 1 1 335d 335d 0/2 auto-obsoleted due to no activity on 2026/02/10 14:54
linux-6.6 INFO: task hung in vt_ioctl (2) 1 1 7d11h 7d11h 0/2 upstream: reported on 2026/09/26 15:27
upstream INFO: task hung in vt_ioctl (4) serial 1 1 1109d 1109d 0/29 auto-obsoleted due to no activity on 2023/12/19 05:20
upstream INFO: task hung in vt_ioctl (6) kernel 1 1 411d 411d 0/29 auto-obsoleted due to no activity on 2025/11/16 03:48
linux-6.1 INFO: task hung in vt_ioctl 1 1 65d 65d 0/3 upstream: reported on 2026/07/30 13:55
linux-4.19 INFO: task hung in vt_ioctl 1 1 2320d 2320d 0/1 auto-closed as invalid on 2020/09/24 20:12
upstream INFO: task hung in vt_ioctl (3) serial 1 1 1289d 1289d 0/29 auto-obsoleted due to no activity on 2023/06/22 09:16
upstream INFO: task hung in vt_ioctl serial 1 1 2414d 2414d 0/29 auto-closed as invalid on 2020/05/23 20:53
upstream INFO: task hung in vt_ioctl (2) serial 1 2 2283d 2322d 0/29 auto-closed as invalid on 2020/10/01 08:58
upstream INFO: task hung in vt_ioctl (5) kernel 1 1 574d 574d 0/29 auto-obsoleted due to no activity on 2025/06/06 19:57

Sample crash report:
INFO: task syz.1.1382:12214 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.1382      state:D stack:27888 pid:12214 ppid: 10764 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
 vt_ioctl+0x155b/0x1ca0 drivers/tty/vt/vt_ioctl.c:851
 tty_ioctl+0x848/0xc30 drivers/tty/tty_io.c:2810
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
 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: 0033:0x7f5f5121e159
RSP: 002b:00007f5f4f434028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f5f514a6180 RCX: 00007f5f5121e159
RDX: 0000000000000009 RSI: 0000000000005606 RDI: 0000000000000006
RBP: 00007f5f512b506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5f514a6218 R14: 00007f5f514a6180 R15: 00007ffe25456f88
 </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 dhcpcd/3849:
 #0: ffffffff8d4358c8 (vlan_ioctl_mutex){+.+.}-{3:3}, at: sock_ioctl+0x21b/0x700 net/socket.c:1229
 #1: ffffffff8d44d548 (rtnl_mutex){+.+.}-{3:3}, at: vlan_ioctl_handler+0xef/0x5d0 net/8021q/vlan.c:581
2 locks held by getty/3940:
 #0: ffff88802c69e098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc900026562e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x594/0x1a50 drivers/tty/n_tty.c:2158
1 lock held by syz-executor/4173:
 #0: ffff88804bf0c868 (&pipe->mutex/1){+.+.}-{3:3}, at: __pipe_lock fs/pipe.c:102 [inline]
 #0: ffff88804bf0c868 (&pipe->mutex/1){+.+.}-{3:3}, at: pipe_read+0x11f/0x12d0 fs/pipe.c:243
3 locks held by kworker/u4:5/4241:
 #0: ffff888016c79138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc900031cfd00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffffffff8d44d548 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xa/0x50 net/core/link_watch.c:251
3 locks held by kworker/0:6/4306:
 #0: ffff888016c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc900032cfd00 ((work_completion)(&(&nsim_dev->trap_data->trap_report_dw)->work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffff8880686a5400 (&nsim_dev->port_list_lock){+.+.}-{3:3}, at: nsim_dev_trap_report_work+0x56/0xab0 drivers/net/netdevsim/dev.c:757
4 locks held by kworker/u4:7/4330:
2 locks held by kworker/u4:8/4333:
 #0: ffff888016c79138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc900031dfd00 ((reaper_work).work){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
2 locks held by kworker/u4:9/4355:
 #0: ffff888016c79138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc900030bfd00 (connector_reaper_work){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
8 locks held by kworker/u4:10/4357:
 #0: ffff888016dcd938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc9000338fd00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffffffff8d441610 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x148/0xba0 net/core/net_namespace.c:589
 #3: ffffffff8d472b28 (devlink_mutex){+.+.}-{3:3}, at: devlink_pernet_pre_exit+0xa4/0x310 net/core/devlink.c:11534
 #4: ffff8880686a4660 (&nsim_bus_dev->nsim_bus_reload_lock){+.+.}-{3:3}, at: nsim_dev_reload_down+0x57/0x160 drivers/net/netdevsim/dev.c:870
 #5: ffff8880686a5400 (&nsim_dev->port_list_lock){+.+.}-{3:3}, at: nsim_dev_port_del_all drivers/net/netdevsim/dev.c:1359 [inline]
 #5: ffff8880686a5400 (&nsim_dev->port_list_lock){+.+.}-{3:3}, at: nsim_dev_reload_destroy+0x109/0x230 drivers/net/netdevsim/dev.c:1561
 #6: ffffffff8d44d548 (rtnl_mutex){+.+.}-{3:3}, at: nsim_destroy+0x3b/0x150 drivers/net/netdevsim/netdev.c:381
 #7: ffffffff8c3239e8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:290 [inline]
 #7: ffffffff8c3239e8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x2d1/0x750 kernel/rcu/tree_exp.h:845
2 locks held by kworker/u4:13/4423:
 #0: ffff888016c79138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc9000452fd00 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
2 locks held by kworker/0:12/4984:
5 locks held by syz.1.1078/10185:
1 lock held by syz-executor/12011:
4 locks held by kworker/u4:1/12553:
1 lock held by syz-executor/13040:
 #0: ffffffff8d44d548 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d44d548 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x79f/0xf10 net/core/rtnetlink.c:5695
1 lock held by udevd/13063:
6 locks held by syz.9.1563/13154:
2 locks held by modprobe/13155:

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

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 09/16/2026
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 (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/01 10:47 linux-5.15.y 0248c33e835e 38f7f0d1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in vt_ioctl
2026/10/01 10:46 linux-5.15.y 0248c33e835e 38f7f0d1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in vt_ioctl
2026/08/11 00:01 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 vt_ioctl
* Struck through repros no longer work on HEAD.