syzbot

INFO: task syz-executor238:2151 blocked for more than 140 seconds.
      Not tainted 4.9.189+ #22
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor238 D28632  2151   2149 0x00000000
 0000000000000083 ffff8801cc8baf80 0000000000000000 ffff8801db721000
 ffff8801da6b2f80 ffff8801db721018 ffff8801cb6bf4b8 ffffffff8281887e
 ffffffff82e2f0f8 ffffffff8120cd80 00ffffff83c84a80 ffff8801db7218f0
Call Trace:
 [<0000000027161c54>] schedule+0x92/0x1c0 kernel/sched/core.c:3546
 [<0000000033a686e7>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579
 [<00000000699916dd>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<00000000699916dd>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621
 [<00000000c3d8fdf3>] fuse_lock_inode+0xad/0xe0 fs/fuse/inode.c:364
 [<000000000e65b894>] fuse_lookup+0x89/0x3b0 fs/fuse/dir.c:406
 [<00000000af432572>] lookup_slow+0x24b/0x480 fs/namei.c:1709
 [<00000000350bb589>] walk_component+0x71e/0xce0 fs/namei.c:1825
 [<0000000074472230>] link_path_walk+0x8b4/0x1210 fs/namei.c:2161
 [<00000000c5a67406>] path_openat+0x18e/0x2f60 fs/namei.c:3580
 [<00000000870ccc93>] do_filp_open+0x1a1/0x280 fs/namei.c:3615
 [<00000000e83c734f>] do_sys_open+0x2f0/0x610 fs/open.c:1097
 [<00000000126ed05a>] SYSC_open fs/open.c:1115 [inline]
 [<00000000126ed05a>] SyS_open+0x2d/0x40 fs/open.c:1110
 [<00000000386d08fb>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288
 [<000000001a97ce56>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by init/1:
 #0:  (&type->i_mutex_dir_key#6){++++++}, at: [<00000000c82f3755>] inode_lock_shared include/linux/fs.h:781 [inline]
 #0:  (&type->i_mutex_dir_key#6){++++++}, at: [<00000000c82f3755>] lookup_slow+0x160/0x480 fs/namei.c:1686
 #1:  (&fi->mutex){+.+.+.}, at: [<00000000c3d8fdf3>] fuse_lock_inode+0xad/0xe0 fs/fuse/inode.c:364
2 locks held by khungtaskd/24:
 #0:  (rcu_read_lock){......}, at: [<00000000fad4536d>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline]
 #0:  (rcu_read_lock){......}, at: [<00000000fad4536d>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263
 #1:  (tasklist_lock){.+.+..}, at: [<000000001710e430>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4336
2 locks held by cron/1945:
 #0:  (&type->i_mutex_dir_key#6){++++++}, at: [<00000000c82f3755>] inode_lock_shared include/linux/fs.h:781 [inline]
 #0:  (&type->i_mutex_dir_key#6){++++++}, at: [<00000000c82f3755>] lookup_slow+0x160/0x480 fs/namei.c:1686
 #1:  (&fi->mutex){+.+.+.}, at: [<00000000c3d8fdf3>] fuse_lock_inode+0xad/0xe0 fs/fuse/inode.c:364
2 locks held by getty/2021:
 #0:  (&tty->ldisc_sem){++++++}, at: [<0000000070cd5aff>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<00000000ea98a4ba>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156
2 locks held by syz-executor238/2151:
 #0:  (&type->i_mutex_dir_key#6){++++++}, at: [<00000000c82f3755>] inode_lock_shared include/linux/fs.h:781 [inline]
 #0:  (&type->i_mutex_dir_key#6){++++++}, at: [<00000000c82f3755>] lookup_slow+0x160/0x480 fs/namei.c:1686
 #1:  (&fi->mutex){+.+.+.}, at: [<00000000c3d8fdf3>] fuse_lock_inode+0xad/0xe0 fs/fuse/inode.c:364
2 locks held by syz-executor238/2156:
 #0:  (&type->i_mutex_dir_key#6){++++++}, at: [<00000000c82f3755>] inode_lock_shared include/linux/fs.h:781 [inline]
 #0:  (&type->i_mutex_dir_key#6){++++++}, at: [<00000000c82f3755>] lookup_slow+0x160/0x480 fs/namei.c:1686
 #1:  (&fi->mutex){+.+.+.}, at: [<00000000c3d8fdf3>] fuse_lock_inode+0xad/0xe0 fs/fuse/inode.c:364

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

NMI backtrace for cpu 1
CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.189+ #22
 ffff8801d98d7cc8 ffffffff81b65c01 0000000000000001 0000000000000000
 0000000000000001 ffffffff81099a01 dffffc0000000000 ffff8801d98d7d00
 ffffffff81b70e9c 0000000000000001 0000000000000000 0000000000000001
Call Trace:
 [<00000000d7ce4678>] __dump_stack lib/dump_stack.c:15 [inline]
 [<00000000d7ce4678>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<0000000057a4a560>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99
 [<000000003c53ab43>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60
 [<0000000054114b31>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<00000000e6b9a75e>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<00000000e6b9a75e>] check_hung_task kernel/hung_task.c:126 [inline]
 [<00000000e6b9a75e>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline]
 [<00000000e6b9a75e>] watchdog+0x670/0xaf0 kernel/hung_task.c:263
 [<00000000360f3295>] kthread+0x278/0x310 kernel/kthread.c:211
 [<000000000c9c0db1>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:375
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff828279d1