INFO: task syz-executor.1:2131 blocked for more than 140 seconds.
      Not tainted 4.9.165+ #28
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.1  D25016  2131      1 0x00000004
 ffff8801c8194740 ffff8801d1719600 ffff8801db721000 ffff8801d1495f00
 ffff8801db721018 ffff8801a691f598 ffffffff827fbd7e ffffffff81bafe1c
 ffffffff81207f30 00ffffff83c7e4e0 ffff8801db7218f0 1ffff10034d23ea2
Call Trace:
 [<ffffffff827fd652>] schedule+0x92/0x1c0 kernel/sched/core.c:3546
 [<ffffffff827fdff3>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579
 [<ffffffff827fff4d>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff827fff4d>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621
 [<ffffffff81896abd>] fuse_lock_inode+0xad/0xe0 fs/fuse/inode.c:364
 [<ffffffff81877d69>] fuse_lookup+0x89/0x3b0 fs/fuse/dir.c:406
 [<ffffffff815301eb>] lookup_slow+0x24b/0x480 fs/namei.c:1709
 [<ffffffff8153f45e>] walk_component+0x71e/0xce0 fs/namei.c:1825
 [<ffffffff815402b7>] link_path_walk+0x897/0x1200 fs/namei.c:2161
 [<ffffffff815411c7>] path_mountpoint+0x67/0x6d0 fs/namei.c:2737
 [<ffffffff81545bdf>] filename_mountpoint+0x17f/0x350 fs/namei.c:2758
 [<ffffffff815472da>] user_path_mountpoint_at+0x3a/0x50 fs/namei.c:2788
 [<ffffffff8157d426>] SYSC_umount fs/namespace.c:1722 [inline]
 [<ffffffff8157d426>] SyS_umount+0x136/0xd30 fs/namespace.c:1706
 [<ffffffff810056bd>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285
 [<ffffffff8280c213>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/24:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131d3fc>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131d3fc>] watchdog+0x13c/0xae0 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff8140072f>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4336
2 locks held by getty/2028:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff8280a2e3>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff81d3daee>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156
2 locks held by syz-executor.1/2131:
 #0:  (&type->i_mutex_dir_key#7){++++++}, at: [<ffffffff81530100>] inode_lock_shared include/linux/fs.h:778 [inline]
 #0:  (&type->i_mutex_dir_key#7){++++++}, at: [<ffffffff81530100>] lookup_slow+0x160/0x480 fs/namei.c:1686
 #1:  (&fi->mutex){+.+.+.}, at: [<ffffffff81896abd>] fuse_lock_inode+0xad/0xe0 fs/fuse/inode.c:364
2 locks held by syz-executor.1/4114:
 #0:  (&type->i_mutex_dir_key#7){++++++}, at: [<ffffffff81530100>] inode_lock_shared include/linux/fs.h:778 [inline]
 #0:  (&type->i_mutex_dir_key#7){++++++}, at: [<ffffffff81530100>] lookup_slow+0x160/0x480 fs/namei.c:1686
 #1:  (&fi->mutex){+.+.+.}, at: [<ffffffff81896abd>] fuse_lock_inode+0xad/0xe0 fs/fuse/inode.c:364

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

NMI backtrace for cpu 1
CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.165+ #28
 ffff8801d98d7cc8 ffffffff81b4baf1 0000000000000001 0000000000000000
 0000000000000001 ffffffff81097401 dffffc0000000000 ffff8801d98d7d00
 ffffffff81b56d7c 0000000000000001 0000000000000000 0000000000000001
Call Trace:
 [<ffffffff81b4baf1>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81b4baf1>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<ffffffff81b56d7c>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81b56d04>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60
 [<ffffffff81097594>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff8131d921>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff8131d921>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff8131d921>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff8131d921>] watchdog+0x661/0xae0 kernel/hung_task.c:239
 [<ffffffff81142298>] kthread+0x278/0x310 kernel/kthread.c:211
 [<ffffffff8280c3dc>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff8280adf2