syzbot
INFO: task hung in console_callback
Status:
upstream: reported on 2026/08/04 05:49
Reported-by: syzbot+e82edd5c49e7e3284069@syzkaller.appspotmail.com
First crash: 98d, last: 14d
Sample crash report:
INFO: task kworker/0:2:1109 blocked for more than 144 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:2 state:D stack:23088 pid: 1109 ppid: 2 flags:0x00004000
Workqueue: events console_callback
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
console_callback+0x66/0x440 drivers/tty/vt/vt.c:2980
process_one_work+0x867/0xff0 kernel/workqueue.c:2310
worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
kthread+0x42e/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
Showing all locks held in the system:
1 lock held by khungtaskd/27:
#0: ffffffff8d11efa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
4 locks held by kworker/u4:3/413:
2 locks held by kworker/0:2/1109:
#0: ffff888017870938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
#1: ffffc9000469fd00 (console_work){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
4 locks held by kworker/u4:5/4291:
2 locks held by kworker/u4:10/4472:
2 locks held by getty/15271:
#0: ffff88802cffe098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
#1: ffffc900013482e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x594/0x1a50 drivers/tty/n_tty.c:2158
5 locks held by syz.2.3185/22224:
2 locks held by syz.5.3296/23244:
#0: ffffffff8d7f6648 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2064 [inline]
#0: ffffffff8d7f6648 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x20a/0xcd0 drivers/tty/tty_io.c:2148
#1: ffff8880768551c0 (&tty->legacy_mutex){+.+.}-{3:3}, at: tty_init_dev+0x6f/0x470 drivers/tty/tty_io.c:1430
1 lock held by syz.1.3314/23559:
#0: ffffffff8d7f6648 (tty_mutex){+.+.}-{3:3}, at: ptmx_open+0xd2/0x2c0 drivers/tty/pty.c:823
1 lock held by syz.8.3320/23650:
#0: ffffffff8d7f6648 (tty_mutex){+.+.}-{3:3}, at: ptmx_open+0xd2/0x2c0 drivers/tty/pty.c:823
1 lock held by syz.9.3321/23649:
#0: ffffffff8d7f6648 (tty_mutex){+.+.}-{3:3}, at: ptmx_open+0xd2/0x2c0 drivers/tty/pty.c:823
1 lock held by syz.3.3348/24680:
#0: ffffffff8d7f6648 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2064 [inline]
#0: ffffffff8d7f6648 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x20a/0xcd0 drivers/tty/tty_io.c:2148
1 lock held by syz.4.3356/25257:
#0: ffffffff8d7f6648 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2064 [inline]
#0: ffffffff8d7f6648 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x20a/0xcd0 drivers/tty/tty_io.c:2148
1 lock held by syz.6.3359/25302:
#0: ffffffff8d7f6648 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2064 [inline]
#0: ffffffff8d7f6648 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x20a/0xcd0 drivers/tty/tty_io.c:2148
3 locks held by kworker/0:13/26677:
1 lock held by syz.1.3412/26725:
#0: ffffffff8d7f6648 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2064 [inline]
#0: ffffffff8d7f6648 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x20a/0xcd0 drivers/tty/tty_io.c:2148
1 lock held by syz.0.3428/27110:
#0: ffffffff8d7f6648 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2064 [inline]
#0: ffffffff8d7f6648 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x20a/0xcd0 drivers/tty/tty_io.c:2148
1 lock held by syz.5.3429/27127:
#0: ffffffff8d7f6648 (tty_mutex){+.+.}-{3:3}, at: ptmx_open+0xd2/0x2c0 drivers/tty/pty.c:823
1 lock held by syz.9.3506/28131:
#0: ffffffff8d7f6648 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2064 [inline]
#0: ffffffff8d7f6648 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x20a/0xcd0 drivers/tty/tty_io.c:2148
1 lock held by syz.4.3534/28519:
#0: ffffffff8d7f6648 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2064 [inline]
#0: ffffffff8d7f6648 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x20a/0xcd0 drivers/tty/tty_io.c:2148
1 lock held by syz.2.3568/28975:
#0: ffffffff8d7f6648 (tty_mutex){+.+.}-{3:3}, at: ptmx_open+0xd2/0x2c0 drivers/tty/pty.c:823
1 lock held by syz.7.3632/29575:
#0: ffffffff8d7f6648 (tty_mutex){+.+.}-{3:3}, at: ptmx_open+0xd2/0x2c0 drivers/tty/pty.c:823
=============================================
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>
* Struck through repros no longer work on HEAD.