INFO: task syz-executor7:8960 blocked for more than 120 seconds.
      Not tainted 4.9.85-ge0b05e6 #49
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor7   D28448  8960   3868 0x00000004
 ffff8801ae568000 0000000000000000 ffff8801cb2c6a00 ffff8801d9b73000
 ffff8801db321b98 ffff8801c0d5f3e0 ffffffff838a438b 0000000041b58ab3
 ffffffff841937f8 00ffffff8123c030 ffff8801db322468 ffff8801db322490
Call Trace:
 [<ffffffff838a592f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3550
 [<ffffffff838b1a8c>] schedule_timeout+0x56c/0x10b0 kernel/time/timer.c:1768
 [<ffffffff838a3b3e>] io_schedule_timeout+0x1be/0x390 kernel/sched/core.c:5172
 [<ffffffff838a6da9>] io_schedule include/linux/sched.h:460 [inline]
 [<ffffffff838a6da9>] bit_wait_io+0x19/0xa0 kernel/sched/wait.c:582
 [<ffffffff838a6612>] __wait_on_bit_lock+0xc2/0x1c0 kernel/sched/wait.c:421
 [<ffffffff81432e1f>] __lock_page+0xff/0x160 mm/filemap.c:934
 [<ffffffff8146b0b8>] lock_page include/linux/pagemap.h:454 [inline]
 [<ffffffff8146b0b8>] invalidate_inode_pages2_range+0x668/0xad0 mm/truncate.c:614
 [<ffffffff8143bac8>] generic_file_direct_write+0x418/0x500 mm/filemap.c:2629
 [<ffffffff8143bdcf>] __generic_file_write_iter+0x21f/0x570 mm/filemap.c:2823
 [<ffffffff8162d47c>] blkdev_write_iter+0x1bc/0x380 fs/block_dev.c:1718
 [<ffffffff8156e4c3>] do_iter_readv_writev+0x3d3/0x4b0 fs/read_write.c:695
 [<ffffffff81570a16>] do_readv_writev+0x2e6/0x740 fs/read_write.c:871
 [<ffffffff815713a7>] vfs_writev+0x87/0xc0 fs/read_write.c:910
 [<ffffffff815714c6>] do_writev+0xe6/0x250 fs/read_write.c:943
 [<ffffffff81574517>] SYSC_writev fs/read_write.c:1016 [inline]
 [<ffffffff81574517>] SyS_writev+0x27/0x30 fs/read_write.c:1013
 [<ffffffff81006504>] do_syscall_64+0x1a4/0x490 arch/x86/entry/common.c:282
 [<ffffffff838b5413>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/514:
 #0:  (rcu_read_lock){......}, at: [<ffffffff813730b5>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff813730b5>] watchdog+0x125/0xa70 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81238190>] debug_show_all_locks+0x70/0x280 kernel/locking/lockdep.c:4336
2 locks held by getty/3784:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838b3602>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff8200ac24>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133
1 lock held by blkid/8728:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff8162ddec>] __blkdev_put+0xbc/0x7e0 fs/block_dev.c:1579

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

NMI backtrace for cpu 0
CPU: 0 PID: 514 Comm: khungtaskd Not tainted 4.9.85-ge0b05e6 #49
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d9377d00 ffffffff81d95739 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810bb190 ffff8801d9377d38
 ffffffff81da085d 0000000000000000 0000000000000000 ffff8801c1d9e418
Call Trace:
 [<ffffffff81d95739>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d95739>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81da085d>] nmi_cpu_backtrace+0xfd/0x120 lib/nmi_backtrace.c:99
 [<ffffffff81da0997>] nmi_trigger_cpumask_backtrace+0x117/0x190 lib/nmi_backtrace.c:60
 [<ffffffff810bb284>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81373680>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81373680>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81373680>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81373680>] watchdog+0x6f0/0xa70 kernel/hung_task.c:239
 [<ffffffff8119a7bd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838b55ac>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:374
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 1808 Comm: kworker/1:3 Not tainted 4.9.85-ge0b05e6 #49
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_power_efficient gc_worker
c
task: ffff8801ceffc800 task.stack: ffff8801cefe8000
RIP: 0010:[<ffffffff8123a3b5>] 
c [<ffffffff8123a3b5>] mark_lock+0x15/0xfd0 kernel/locking/lockdep.c:3032
RSP: 0018:ffff8801cefefb40  EFLAGS: 00000002
RAX: dffffc0000000000 RBX: 0000000000000001 RCX: 0000000000000006
RDX: 0000000000000006 RSI: ffff8801ceffd0d8 RDI: ffff8801ceffc800
RBP: ffff8801cefefb48 R08: 1ffff10039dffa24 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000007
R13: ffff8801ceffc800 R14: dffffc0000000000 R15: ffff8801ceffd0d8
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000008cb000 CR3: 00000001b5a22000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801ceffd0b0
c ffff8801cefefb90
c ffffffff8123b41f
c 0000000000000000
c
 ffff880100000006
c ffff8801ceffc800
c ffffffff830b643c
c 0000000000000293
c
 ffffffff84a3dde8
c fffffbfff0881200
c ffff8801cefefbb0
c ffffffff8123b7fb
c
Call Trace:
 [<ffffffff8123b41f>] mark_held_locks+0xaf/0x100 kernel/locking/lockdep.c:2660
 [<ffffffff8123b7fb>] __trace_hardirqs_on_caller kernel/locking/lockdep.c:2689 [inline]
 [<ffffffff8123b7fb>] trace_hardirqs_on_caller+0x38b/0x590 kernel/locking/lockdep.c:2736
 [<ffffffff8123ba0d>] trace_hardirqs_on+0xd/0x10 kernel/locking/lockdep.c:2743
 [<ffffffff830b643c>] seqcount_lockdep_reader_access include/linux/seqlock.h:82 [inline]
 [<ffffffff830b643c>] read_seqcount_begin include/linux/seqlock.h:163 [inline]
 [<ffffffff830b643c>] nf_conntrack_get_ht include/net/netfilter/nf_conntrack.h:325 [inline]
 [<ffffffff830b643c>] gc_worker+0x14c/0x610 net/netfilter/nf_conntrack_core.c:968
 [<ffffffff811898a0>] process_one_work+0x7e0/0x1610 kernel/workqueue.c:2092
 [<ffffffff8118a7b0>] worker_thread+0xe0/0x10d0 kernel/workqueue.c:2226
 [<ffffffff8119a7bd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838b55ac>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:374
Code: 
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c