INFO: task syz-executor2:22524 blocked for more than 120 seconds.
      Not tainted 4.9.110-g00a0bcb #4
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor2   D28488 22524  20976 0x00000002
 ffff8801cf924800 ffff8801cf6f8fc0 ffff8801c2699500 ffff88019d5d4800
 ffff8801db321c18 ffff8801a5357568 ffffffff839e6ded ffffffff812355f7
 0000000000000000 ffff8801cf9250c0 0000000600000007 ffff8801db3224e8
Call Trace:
 [<ffffffff839e83ef>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839f3a28>] __rwsem_down_write_failed_common kernel/locking/rwsem-xadd.c:526 [inline]
 [<ffffffff839f3a28>] rwsem_down_write_failed+0x598/0x990 kernel/locking/rwsem-xadd.c:555
 [<ffffffff81ee6607>] call_rwsem_down_write_failed+0x17/0x30 arch/x86/lib/rwsem.S:105
 [<ffffffff839f17fc>] __down_write arch/x86/include/asm/rwsem.h:125 [inline]
 [<ffffffff839f17fc>] down_write+0x5c/0xa0 kernel/locking/rwsem.c:54
 [<ffffffff8211bf31>] n_tty_flush_buffer+0x21/0x310 drivers/tty/n_tty.c:359
 [<ffffffff8212a0d9>] tty_ldisc_hangup+0x89/0x5b0 drivers/tty/tty_ldisc.c:658
 [<ffffffff82111567>] __tty_hangup.part.22+0x5f7/0xb00 drivers/tty/tty_io.c:744
 [<ffffffff82111a91>] __tty_hangup drivers/tty/tty_io.c:694 [inline]
 [<ffffffff82111a91>] tty_vhangup+0x21/0x30 drivers/tty/tty_io.c:817
 [<ffffffff82131974>] pty_close+0x374/0x4d0 drivers/tty/pty.c:74
 [<ffffffff821136a0>] tty_release+0x370/0xd00 drivers/tty/tty_io.c:1813
 [<ffffffff81578193>] __fput+0x263/0x700 fs/file_table.c:208
 [<ffffffff815786b5>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff8119832c>] task_work_run+0x10c/0x180 kernel/task_work.c:116
 [<ffffffff81140e41>] exit_task_work include/linux/task_work.h:21 [inline]
 [<ffffffff81140e41>] do_exit+0x9e1/0x27c0 kernel/exit.c:837
 [<ffffffff81146f41>] do_group_exit+0x111/0x340 kernel/exit.c:941
 [<ffffffff81169d9f>] get_signal+0x4cf/0x1450 kernel/signal.c:2321
 [<ffffffff81052637>] do_signal+0x87/0x19f0 arch/x86/kernel/signal.c:807
 [<ffffffff81005581>] exit_to_usermode_loop+0xe1/0x120 arch/x86/entry/common.c:157
 [<ffffffff810064d4>] prepare_exit_to_usermode arch/x86/entry/common.c:191 [inline]
 [<ffffffff810064d4>] syscall_return_slowpath arch/x86/entry/common.c:260 [inline]
 [<ffffffff810064d4>] do_syscall_64+0x364/0x490 arch/x86/entry/common.c:287
 [<ffffffff839f7cd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by kworker/1:1/24:
 #0:  ("events"){.+.+.+}, at: [<ffffffff8118d02e>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("events"){.+.+.+}, at: [<ffffffff8118d02e>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("events"){.+.+.+}, at: [<ffffffff8118d02e>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("events"){.+.+.+}, at: [<ffffffff8118d02e>] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085
 #1:  ((&rew.rew_work)){+.+...}, at: [<ffffffff8118d068>] process_one_work+0x728/0x1500 kernel/workqueue.c:2089
2 locks held by khungtaskd/519:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136662c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8136662c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81425cb7>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3773:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f5e92>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211e1e2>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
4 locks held by syz-executor2/22524:
 #0:  (&tty->legacy_mutex){+.+.+.}, at: [<ffffffff8212eb3a>] tty_lock+0x6a/0xd0 drivers/tty/tty_mutex.c:18
 #1:  (&tty->legacy_mutex/1){+.+.+.}, at: [<ffffffff8212eb3a>] tty_lock+0x6a/0xd0 drivers/tty/tty_mutex.c:18
 #2:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82129390>] tty_ldisc_ref+0x20/0x80 drivers/tty/tty_ldisc.c:296
 #3:  (&o_tty->termios_rwsem/1){++++..}, at: [<ffffffff8211bf31>] n_tty_flush_buffer+0x21/0x310 drivers/tty/n_tty.c:359
2 locks held by syz-executor3/29258:
 #0:  (rtnl_mutex){+.+.+.}, at: [<ffffffff830b3937>] rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
 #1:  (rcu_preempt_state.exp_mutex){+.+...}, at: [<ffffffff81282a19>] exp_funnel_lock kernel/rcu/tree_exp.h:256 [inline]
 #1:  (rcu_preempt_state.exp_mutex){+.+...}, at: [<ffffffff81282a19>] _synchronize_rcu_expedited+0x339/0x840 kernel/rcu/tree_exp.h:569

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

NMI backtrace for cpu 1
CPU: 1 PID: 519 Comm: khungtaskd Not tainted 4.9.110-g00a0bcb #4
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8437d08 ffffffff81eb2329 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b9580 ffff8801d8437d40
 ffffffff81ebd627 0000000000000001 0000000000000000 0000000000000002
Call Trace:
 [<ffffffff81eb2329>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb2329>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebd627>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebd5ba>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b9684>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81366bc4>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366bc4>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366bc4>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366bc4>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d04d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f7e9c>] 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
CPU: 0 PID: 29307 Comm: syz-executor4 Not tainted 4.9.110-g00a0bcb #4
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d087e000 task.stack: ffff8801cb198000
RIP: 0010:[<ffffffff8123709a>] 
c [<ffffffff8123709a>] __read_once_size include/linux/compiler.h:243 [inline]
RIP: 0010:[<ffffffff8123709a>] 
c [<ffffffff8123709a>] lookup_chain_cache kernel/locking/lockdep.c:2138 [inline]
RIP: 0010:[<ffffffff8123709a>] 
c [<ffffffff8123709a>] validate_chain kernel/locking/lockdep.c:2236 [inline]
RIP: 0010:[<ffffffff8123709a>] 
c [<ffffffff8123709a>] __lock_acquire+0xf3a/0x4070 kernel/locking/lockdep.c:3345
RSP: 0018:ffff8801db207ce0  EFLAGS: 00000046
RAX: dffffc0000000000 RBX: ffff8801d087e940 RCX: 00000000ffffffc7
RDX: 1ffffffff0aaa060 RSI: ffff8801d087e940 RDI: 0000000000000000
RBP: ffff8801db207e88 R08: ffff8801d087e960 R09: 0000000000000001
R10: ffff8801d087e000 R11: 1ffff1003a10fd27 R12: 0000000000005e80
R13: 0000000000000000 R14: 000000003c63243a R15: 05bc14afc5dd28c2
FS:  00007f11697f7700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2d625000 CR3: 000000019f5c7000 CR4: 00000000001606f0
DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Stack:
 ffff8801db207d98
c 0000000000000046
c ffffffff81f19d8b
c 0000000000000046
c
 ffff8801d087e000
c 0000000000000000
c 0000000000000000
c 0000000000000002
c
 ffff88021fffd01b
c ffff88021fffd017
c ffffffff8558ee80
c ffffed0043fffa03
c
Call Trace:
 [<ffffffff8123ac40>] lock_acquire+0x130/0x3e0 kernel/locking/lockdep.c:3756
 [<ffffffff839f7086>] __raw_spin_lock include/linux/spinlock_api_smp.h:144 [inline]
 [<ffffffff839f7086>] _raw_spin_lock+0x36/0x50 kernel/locking/spinlock.c:151
 [<ffffffff812a5acc>] hrtimer_interrupt+0xfc/0x430 kernel/time/hrtimer.c:1340
 [<ffffffff810b1d34>] local_apic_timer_interrupt+0x74/0xa0 arch/x86/kernel/apic/apic.c:935
 [<ffffffff839fd49c>] smp_apic_timer_interrupt+0x7c/0xa0 arch/x86/kernel/apic/apic.c:959
 [<ffffffff839f9630>] apic_timer_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:648
 <EOI> 
d [<ffffffff81ed01a5>] ? memcmp+0x95/0x160 lib/string.c:768
 [<ffffffff81f651e2>] find_stack lib/stackdepot.c:176 [inline]
 [<ffffffff81f651e2>] depot_save_stack+0x132/0x460 lib/stackdepot.c:225
 [<ffffffff8153aad9>] save_stack+0xa9/0xd0 mm/kasan/kasan.c:511
 [<ffffffff8153b4a2>] set_track mm/kasan/kasan.c:517 [inline]
 [<ffffffff8153b4a2>] kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:582
 [<ffffffff8153819e>] slab_free_hook mm/slub.c:1355 [inline]
 [<ffffffff8153819e>] slab_free_freelist_hook mm/slub.c:1377 [inline]
 [<ffffffff8153819e>] slab_free mm/slub.c:2958 [inline]
 [<ffffffff8153819e>] kmem_cache_free+0xbe/0x310 mm/slub.c:2980
 [<ffffffff8188702a>] jbd2_free_handle include/linux/jbd2.h:1424 [inline]
 [<ffffffff8188702a>] jbd2_journal_stop+0x34a/0x1250 fs/jbd2/transaction.c:1767
 [<ffffffff818065b1>] __ext4_journal_stop+0xd1/0x1c0 fs/ext4/ext4_jbd2.c:98
 [<ffffffff817451b6>] ext4_get_block_trans+0x186/0x270 fs/ext4/inode.c:822
 [<ffffffff81745605>] ext4_dio_get_block+0x75/0xe0 fs/ext4/inode.c:838
 [<ffffffff81637d1b>] get_more_blocks fs/direct-io.c:653 [inline]
 [<ffffffff81637d1b>] do_direct_IO+0x10fb/0x9710 fs/direct-io.c:955
 [<ffffffff81640c70>] do_blockdev_direct_IO+0x940/0x5a80 fs/direct-io.c:1274
 [<ffffffff81645e55>] __blockdev_direct_IO+0xa5/0xd0 fs/direct-io.c:1360
 [<ffffffff81759058>] ext4_direct_IO_write fs/ext4/inode.c:3519 [inline]
 [<ffffffff81759058>] ext4_direct_IO+0x978/0x29a0 fs/ext4/inode.c:3675
 [<ffffffff8143d144>] generic_file_direct_write+0x284/0x510 mm/filemap.c:2642
 [<ffffffff8143d5ef>] __generic_file_write_iter+0x21f/0x540 mm/filemap.c:2822
 [<ffffffff8172cec3>] ext4_file_write_iter+0x463/0xd90 fs/ext4/file.c:165
 [<ffffffff8156eb60>] new_sync_write fs/read_write.c:496 [inline]
 [<ffffffff8156eb60>] __vfs_write+0x3e0/0x580 fs/read_write.c:509
 [<ffffffff81572957>] vfs_write+0x187/0x530 fs/read_write.c:557
 [<ffffffff81576789>] SYSC_write fs/read_write.c:604 [inline]
 [<ffffffff81576789>] SyS_write+0xd9/0x1c0 fs/read_write.c:596
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f7cd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
c10 
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c<0f> 
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c