INFO: task syz-executor.0:868 blocked for more than 143 seconds.
      Not tainted 5.6.0-rc7-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.0  D25984   868    398 0x80004006
Call Trace:
 schedule+0xcd/0x2b0 kernel/sched/core.c:4154
 wdm_flush+0x2ea/0x3c0 drivers/usb/class/cdc-wdm.c:590
 filp_close+0xb4/0x160 fs/open.c:1249
 close_files fs/file.c:388 [inline]
 put_files_struct fs/file.c:416 [inline]
 put_files_struct+0x1d8/0x2e0 fs/file.c:413
 exit_files+0x7e/0xa0 fs/file.c:445
 do_exit+0xb36/0x2c80 kernel/exit.c:796
 do_group_exit+0x125/0x340 kernel/exit.c:899
 get_signal+0x480/0x2470 kernel/signal.c:2739
 do_signal+0x88/0x1490 arch/x86/kernel/signal.c:813
 exit_to_usermode_loop+0x1a2/0x200 arch/x86/entry/common.c:160
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_64+0x4e0/0x5a0 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c829
Code: 48 89 5c 24 08 48 c7 44 24 10 00 00 00 00 e8 5e a4 fa ff 8b 05 18 b8 70 01 48 8b 4c 24 18 85 c0 0f 85 19 01 00 00 48 8b 84 24 <d8> 00 00 00 48 89 48 18 48 8d 7c 24 68 0f 57 c0 48 8d 7f e0 48 89
RSP: 002b:00007f28a9019c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: 0000000000000000 RBX: 000000000050c480 RCX: 000000000045c829
RDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000004
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000ce7 R14: 00000000004cf129 R15: 00007f28a901a6d4

Showing all locks held in the system:
1 lock held by khungtaskd/23:
 #0: ffffffff87108b60 (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x264 kernel/locking/lockdep.c:5331
2 locks held by in:imklog/267:
 #0: ffff8881ca8e8fe0 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xe3/0x100 fs/file.c:826
 #1: ffffffff871958e0 (fs_reclaim){+.+.}, at: syslog_print kernel/printk/printk.c:1364 [inline]
 #1: ffffffff871958e0 (fs_reclaim){+.+.}, at: do_syslog kernel/printk/printk.c:1529 [inline]
 #1: ffffffff871958e0 (fs_reclaim){+.+.}, at: do_syslog+0x791/0x1380 kernel/printk/printk.c:1503

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

NMI backtrace for cpu 1
CPU: 1 PID: 23 Comm: khungtaskd Not tainted 5.6.0-rc7-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+0xef/0x16e lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x1db/0x207 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline]
 watchdog+0xa99/0xfd0 kernel/hung_task.c:289
 kthread+0x318/0x420 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
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 default_idle+0x28/0x300 arch/x86/kernel/process.c:695