INFO: task syz-executor3:8368 blocked for more than 140 seconds.
      Not tainted 4.9.119-g9dc978d #23
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor3   D29384  8368   3884 0x00000004
 ffff8801b5efc800 ffff8801ca81df80 ffff8801ca81df80 ffff8801979f0000
 ffff8801db321c18 ffff8801b795f8a8 ffffffff839ebdcd ffffffff81235627
 0000000000000000 ffff8801b5efd0c0 0000000600000007 ffff8801db3224e8
Call Trace:
 [<ffffffff839ed3cf>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff839f8a08>] __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:526 [inline]
 [<ffffffff839f8a08>] rwsem_down_write_failed+0x598/0x990 kernel/locking/rwsem-xadd.c:555
 [<ffffffff81ee8ec7>] call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:105
 [<ffffffff839f67dc>] __down_write arch/x86/include/asm/rwsem.h:125 [inline]
 [<ffffffff839f67dc>] down_write+0x5c/0xa0 kernel/locking/rwsem.c:54
 [<ffffffff8157ac4c>] grab_super+0x5c/0x170 fs/super.c:364
 [<ffffffff8157bb01>] sget_userns+0x2b1/0xba0 fs/super.c:491
 [<ffffffff8157c4c6>] sget+0xd6/0x120 fs/super.c:559
 [<ffffffff8157c6f6>] mount_bdev+0xe6/0x390 fs/super.c:1073
 [<ffffffff817ac6f4>] ext4_mount+0x34/0x40 fs/ext4/super.c:5614
 [<ffffffff8157e65c>] mount_fs+0x28c/0x370 fs/super.c:1206
 [<ffffffff815dde81>] vfs_kern_mount.part.29+0xd1/0x3d0 fs/namespace.c:991
 [<ffffffff815e57a9>] vfs_kern_mount fs/namespace.c:973 [inline]
 [<ffffffff815e57a9>] do_new_mount fs/namespace.c:2513 [inline]
 [<ffffffff815e57a9>] do_mount+0x3c9/0x2740 fs/namespace.c:2835
 [<ffffffff815e84fe>] SYSC_mount fs/namespace.c:3051 [inline]
 [<ffffffff815e84fe>] SyS_mount+0xfe/0x110 fs/namespace.c:3028
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839fccd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/519:
 #0:  (rcu_read_lock){......}, at: [<ffffffff813667bc>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff813667bc>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81426027>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3780:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839fae72>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff821208d2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142
2 locks held by syz-executor3/8368:
 #0:  (&bdev->bd_fsfreeze_mutex){+.+.+.}, at: [<ffffffff8157c696>] mount_bdev+0x86/0x390 fs/super.c:1067
 #1:  (&type->s_umount_key#47){+.+...}, at: [<ffffffff8157ac4c>] grab_super+0x5c/0x170 fs/super.c:364

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

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.119-g9dc978d #23
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d85cfd08 ffffffff81eb4be9 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b9bd0 ffff8801d85cfd40
 ffffffff81ebfee7 0000000000000000 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb4be9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb4be9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebfee7>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebfe7a>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b9cd4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81366d54>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366d54>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366d54>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366d54>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d0ed>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839fce9c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 8356 Comm: syz-executor3 Not tainted 4.9.119-g9dc978d #23
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801c0ee4800 task.stack: ffff880197af8000
RIP: 0010:[<ffffffff8127bebb>] 
c [<ffffffff8127bebb>] debug_lockdep_rcu_enabled.part.2+0xb/0x60 kernel/rcu/update.c:262
RSP: 0018:ffff880197aff7e0  EFLAGS: 00000202
RAX: dffffc0000000000 RBX: ffff8801cbfb8f08 RCX: 0000000000000000
RDX: 0000000000000004 RSI: ffff8801c0ee50f0 RDI: ffffffff84870b00
RBP: ffff880197aff7f0 R08: ffff8801c0ee5110 R09: 0000000000000001
R10: ffff8801c0ee4800 R11: 1ffff100381dca1d R12: 0000000000000007
R13: dffffc0000000000 R14: 0000000002420840 R15: ffff8801cbfb8f08
FS:  00007fa935548700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f51b4c83000 CR3: 00000001cd06c000 CR4: 00000000001606f0
Stack:
 ffff880197aff7f0
c ffffffff8127bf87
c ffff880197aff858
c ffffffff81438ebf
c
 ffffffff81438e70
c ffffffff81624533
c ffff8801cbfb8dd4
c 0000000000000000
c
 ffff8801cbfb8b80
c 000000000000000f
c 0000000000000002
c 0000000000000007
c
Call Trace:
 [<ffffffff81438ebf>] rcu_read_lock include/linux/rcupdate.h:876 [inline]
 [<ffffffff81438ebf>] find_get_entry+0x4f/0x540 mm/filemap.c:1090
 [<ffffffff8143a2eb>] pagecache_get_page+0x4b/0x720 mm/filemap.c:1201
 [<ffffffff81625809>] find_or_create_page include/linux/pagemap.h:309 [inline]
 [<ffffffff81625809>] grow_dev_page fs/buffer.c:1005 [inline]
 [<ffffffff81625809>] grow_buffers fs/buffer.c:1078 [inline]
 [<ffffffff81625809>] __getblk_slow fs/buffer.c:1105 [inline]
 [<ffffffff81625809>] __getblk_gfp+0x249/0x710 fs/buffer.c:1386
 [<ffffffff816290ed>] __bread_gfp+0x2d/0x270 fs/buffer.c:1420
 [<ffffffff817d0c26>] sb_bread_unmovable include/linux/buffer_head.h:306 [inline]
 [<ffffffff817d0c26>] ext4_fill_super+0x576/0xb490 fs/ext4/super.c:3434
 [<ffffffff8157c8d7>] mount_bdev+0x2c7/0x390 fs/super.c:1100
 [<ffffffff817ac6f4>] ext4_mount+0x34/0x40 fs/ext4/super.c:5614
 [<ffffffff8157e65c>] mount_fs+0x28c/0x370 fs/super.c:1206
 [<ffffffff815dde81>] vfs_kern_mount.part.29+0xd1/0x3d0 fs/namespace.c:991
 [<ffffffff815e57a9>] vfs_kern_mount fs/namespace.c:973 [inline]
 [<ffffffff815e57a9>] do_new_mount fs/namespace.c:2513 [inline]
 [<ffffffff815e57a9>] do_mount+0x3c9/0x2740 fs/namespace.c:2835
 [<ffffffff815e84fe>] SYSC_mount fs/namespace.c:3051 [inline]
 [<ffffffff815e84fe>] SyS_mount+0xfe/0x110 fs/namespace.c:3028
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839fccd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
c00 
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c48 
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c00 
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c55 
c<48> 
c89 
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c48 
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c25 
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c01 
c00 
c48 
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c48 
c