syzbot

INFO: task syz-executor0:10958 blocked for more than 140 seconds.
      Not tainted 4.14.96+ #20
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D28024 10958   5605 0x00000004
Call Trace:
 schedule+0x92/0x1c0 kernel/sched/core.c:3490
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3548
 __mutex_lock_common kernel/locking/mutex.c:833 [inline]
 __mutex_lock+0x559/0x1430 kernel/locking/mutex.c:893
 __fdget_pos+0xa6/0xc0 fs/file.c:768
 fdget_pos include/linux/file.h:67 [inline]
 SYSC_write fs/read_write.c:588 [inline]
 SyS_write+0x72/0x1a0 fs/read_write.c:585
 do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289

Showing all locks held in the system:
1 lock held by khungtaskd/23:
 #0:  (tasklist_lock){.+.+}, at: [<ffffffffa8dffeec>] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4541
2 locks held by getty/1757:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffffa9936f02>] tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:275
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffffa9932327>] n_tty_read+0x1f7/0x1700 drivers/tty/n_tty.c:2156
1 lock held by syz-executor0/10958:
 #0:  (&f->f_pos_lock){+.+.}, at: [<ffffffffa91b9966>] __fdget_pos+0xa6/0xc0 fs/file.c:768

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

NMI backtrace for cpu 1
CPU: 1 PID: 23 Comm: khungtaskd Not tainted 4.14.96+ #20
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xb9/0x10e lib/dump_stack.c:53
 nmi_cpu_backtrace.cold+0x47/0x86 lib/nmi_backtrace.c:101
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at pc 0xffffffffaa450692