INFO: task syz-executor.4:5338 blocked for more than 143 seconds.
      Not tainted 5.9.0-rc1-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.4  state:D stack:26768 pid: 5338 ppid:   344 flags:0x80004006
Call Trace:
 context_switch kernel/sched/core.c:3778 [inline]
 __schedule+0x889/0x1f70 kernel/sched/core.c:4527
 schedule+0xcd/0x2b0 kernel/sched/core.c:4602
 wdm_flush+0x2e9/0x3c0 drivers/usb/class/cdc-wdm.c:590
 filp_close+0xb4/0x170 fs/open.c:1276
 close_files fs/file.c:401 [inline]
 put_files_struct fs/file.c:429 [inline]
 put_files_struct+0x1d0/0x350 fs/file.c:426
 exit_files+0x7e/0xa0 fs/file.c:458
 do_exit+0xb75/0x2890 kernel/exit.c:801
 do_group_exit+0x125/0x310 kernel/exit.c:903
 get_signal+0x42d/0x1f10 kernel/signal.c:2757
 arch_do_signal+0x88/0x1a00 arch/x86/kernel/signal.c:811
 exit_to_user_mode_loop kernel/entry/common.c:135 [inline]
 exit_to_user_mode_prepare+0xf9/0x150 kernel/entry/common.c:166
 syscall_exit_to_user_mode+0x36/0x260 kernel/entry/common.c:241
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45d5b9
Code: Bad RIP value.
RSP: 002b:00007f3adebd7cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000118cf48 RCX: 000000000045d5b9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000118cf48
RBP: 000000000118cf40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c
R13: 00007ffda745e3df R14: 00007f3adebd89c0 R15: 000000000118cf4c

Showing all locks held in the system:
1 lock held by khungtaskd/23:
 #0: ffffffff87313620 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x264 kernel/locking/lockdep.c:5825
1 lock held by in:imklog/221:
2 locks held by agetty/254:
 #0: ffff8881d45ef098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267
 #1: ffffc900009f22e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x223/0x1a30 drivers/tty/n_tty.c:2156
5 locks held by kworker/1:5/3055:
2 locks held by agetty/32753:
 #0: ffff8881c59c7098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:267
 #1: ffffc9000fea82e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x223/0x1a30 drivers/tty/n_tty.c:2156

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

NMI backtrace for cpu 1
CPU: 1 PID: 23 Comm: khungtaskd Not tainted 5.9.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0xf6/0x16e lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x74/0xb6 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1da/0x1f4 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:209 [inline]
 watchdog+0xd6a/0xfd0 kernel/hung_task.c:295
 kthread+0x392/0x470 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:60 [inline]
NMI backtrace for cpu 0 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:103 [inline]
NMI backtrace for cpu 0 skipped: idling at acpi_safe_halt+0x72/0x90 drivers/acpi/processor_idle.c:111