INFO: task syz-executor6:14875 blocked for more than 120 seconds.
      Not tainted 4.9.77-g033d019 #14
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor6   D29584 14875   5085 0x00000004
 ffff8801b42d8000 ffff8801d95aca80 ffff8801d5c33480 ffff8801b42db000
 ffff8801db221b98 ffff8801ca82fb00 ffffffff838a1adb 0000000041b58ab3
 ffffffff84193178 00ffffff8123bda0 ffff8801db222468 ffff8801db222490
Call Trace:
 [<ffffffff838a307f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3550
 [<ffffffff838af1dc>] schedule_timeout+0x56c/0x10b0 kernel/time/timer.c:1768
 [<ffffffff838a128e>] io_schedule_timeout+0x1be/0x390 kernel/sched/core.c:5172
 [<ffffffff838a49ee>] do_wait_for_common kernel/sched/completion.c:75 [inline]
 [<ffffffff838a49ee>] __wait_for_common kernel/sched/completion.c:93 [inline]
 [<ffffffff838a49ee>] wait_for_common_io kernel/sched/completion.c:107 [inline]
 [<ffffffff838a49ee>] wait_for_completion_io+0x20e/0x2e0 kernel/sched/completion.c:155
 [<ffffffff81cdaabb>] submit_bio_wait+0x11b/0x180 block/bio.c:885
 [<ffffffff81d0dc67>] blkdev_issue_flush+0x157/0x220 block/blk-flush.c:518
 [<ffffffff81629ed5>] blkdev_fsync+0x85/0xb0 fs/block_dev.c:378
 [<ffffffff8161583a>] vfs_fsync_range+0x10a/0x250 fs/sync.c:195
 [<ffffffff816159f2>] vfs_fsync fs/sync.c:209 [inline]
 [<ffffffff816159f2>] do_fsync+0x42/0xb0 fs/sync.c:219
 [<ffffffff81616176>] SYSC_fsync fs/sync.c:228 [inline]
 [<ffffffff81616176>] SyS_fsync+0x16/0x20 fs/sync.c:226
 [<ffffffff838b2b6e>] entry_SYSCALL_64_fastpath+0x29/0xe8

Showing all locks held in the system:
2 locks held by khungtaskd/514:
 #0:  (rcu_read_lock){......}, at: [<ffffffff81372d85>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff81372d85>] watchdog+0x125/0xa70 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81237f00>] debug_show_all_locks+0x70/0x280 kernel/locking/lockdep.c:4336
2 locks held by getty/3302:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838b0d52>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff82009514>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133

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

NMI backtrace for cpu 0
CPU: 0 PID: 514 Comm: khungtaskd Not tainted 4.9.77-g033d019 #14
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d959fd00 ffffffff81d941c9 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810babe0 ffff8801d959fd38
 ffffffff81d9f2ed 0000000000000000 0000000000000000 ffff8801d8008418
Call Trace:
 [<ffffffff81d941c9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d941c9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81d9f2ed>] nmi_cpu_backtrace+0xfd/0x120 lib/nmi_backtrace.c:99
 [<ffffffff81d9f427>] nmi_trigger_cpumask_backtrace+0x117/0x190 lib/nmi_backtrace.c:60
 [<ffffffff810bacd4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81373350>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81373350>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81373350>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81373350>] watchdog+0x6f0/0xa70 kernel/hung_task.c:239
 [<ffffffff8119a6fd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838b2ea9>] ret_from_fork+0x59/0x70 arch/x86/entry/entry_64.S:466
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.9.77-g033d019 #14
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801da3d3000 task.stack: ffff8801da3e8000
RIP: 0010:[<ffffffff81202e84>] 
c [<ffffffff81202e84>] should_we_balance kernel/sched/fair.c:9328 [inline]
RIP: 0010:[<ffffffff81202e84>] 
c [<ffffffff81202e84>] load_balance+0x344/0x2e90 kernel/sched/fair.c:9385
RSP: 0018:ffff8801db307c18  EFLAGS: 00000202
RAX: 0000000000000000 RBX: ffff8801da27de40 RCX: 0000000000000001
RDX: 0000000000000100 RSI: 0000000000000040 RDI: ffff8801da27de60
RBP: ffff8801db307da8 R08: ffff8801db307e48 R09: 0000000000000000
R10: dffffc0000000000 R11: ffff8801da3d3000 R12: ffff8801da27dea0
R13: 0000000000000007 R14: ffff8801db307d80 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000086f3d8 CR3: 00000001ce7be000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 0000000000000000
c 0000000041b58ab3
c ffffffff84193178
c ffffffff8123bda0
c
 0000000000000000
c ffff8801db307e48
c ffff8801da3d3888
c 1ffff1003b660f98
c
 0000000000000001
c 0000000000000000
c ffff8801db318558
c ffff8801db321b80
c
Call Trace:
 [<ffffffff81207fa8>] rebalance_domains+0x5f8/0xb00 kernel/sched/fair.c:10031
 [<ffffffff812087a8>] run_rebalance_domains+0x2f8/0x540 kernel/sched/fair.c:10249
 [<ffffffff838b9786>] __do_softirq+0x206/0x951 kernel/softirq.c:284
 [<ffffffff81146bc5>] invoke_softirq kernel/softirq.c:364 [inline]
 [<ffffffff81146bc5>] irq_exit+0x165/0x190 kernel/softirq.c:405
 [<ffffffff838b73ab>] smp_reschedule_interrupt+0x6b/0x80 arch/x86/kernel/smp.c:267
 [<ffffffff838b4fc0>] reschedule_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:764
 <EOI> 
d [<ffffffff838b17c6>] ? native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:53
 [<ffffffff838b0df5>] arch_safe_halt arch/x86/include/asm/paravirt.h:103 [inline]
 [<ffffffff838b0df5>] default_idle+0x55/0x360 arch/x86/kernel/process.c:295
 [<ffffffff8106bc9a>] arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:286
 [<ffffffff838b1c06>] default_idle_call+0x36/0x60 kernel/sched/idle.c:97
 [<ffffffff81226500>] cpuidle_idle_call kernel/sched/idle.c:155 [inline]
 [<ffffffff81226500>] cpu_idle_loop kernel/sched/idle.c:248 [inline]
 [<ffffffff81226500>] cpu_startup_entry+0x2b0/0x380 kernel/sched/idle.c:303
 [<ffffffff810afc93>] start_secondary+0x303/0x3e0 arch/x86/kernel/smpboot.c:254
Code: 
c41 
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ca0 
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cff 
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cb9 
c00 
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c48 
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cd0 
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cff 
cff 
c0f 
cb6 
c00 
c41 
c38 
cc5 
c7c 
c08 
c<84> 
cc0 
c0f 
c85 
c8e 
c20 
c00 
c00 
c3b 
c0d 
c32 
c4c 
c83 
c03 
c0f 
c8d 
c60 
c13 
c00 
c00 
c89 
c