[<ffffffff838d6fd0>] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137
Buffer I/O error on dev loop0, logical block 64, async page read
INFO: task syz-executor6:24524 blocked for more than 120 seconds.
      Not tainted 4.9.92-g4fb542f #2
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor6   D28136 24524   3854 0x20020004
 ffff8801cc29e000 ffff8801d9002a00 ffff8801bdd62a00 ffff8801d89c9800
 ffff8801db221b98 ffff8801c4e3f210 ffffffff838c49cd 1ffff100389c7e36
 ffffffff85316f38 0000000041b58ab3 00ffffff841a4570 ffff8801db222468
Call Trace:
 [<ffffffff838c5fcf>] schedule+0x7f/0x1b0 kernel/sched/core.c:3556
 [<ffffffff838d23e1>] schedule_timeout+0x861/0xf70 kernel/time/timer.c:1768
 [<ffffffff838c41aa>] io_schedule_timeout+0x1ba/0x390 kernel/sched/core.c:5178
 [<ffffffff838c7419>] io_schedule include/linux/sched.h:460 [inline]
 [<ffffffff838c7419>] bit_wait_io+0x19/0xa0 kernel/sched/wait.c:582
 [<ffffffff838c6cbe>] __wait_on_bit_lock+0xce/0x1c0 kernel/sched/wait.c:421
 [<ffffffff8143267f>] __lock_page+0xff/0x160 mm/filemap.c:934
 [<ffffffff8143843f>] lock_page include/linux/pagemap.h:454 [inline]
 [<ffffffff8143843f>] pagecache_get_page+0x40f/0x720 mm/filemap.c:1216
 [<ffffffff8143914c>] grab_cache_page_write_begin+0x6c/0xa0 mm/filemap.c:2685
 [<ffffffff8162832a>] block_write_begin+0x3a/0x180 fs/buffer.c:2093
 [<ffffffff8162d50c>] blkdev_write_begin+0x3c/0x50 fs/block_dev.c:330
 [<ffffffff81433df1>] generic_perform_write+0x301/0x510 mm/filemap.c:2741
 [<ffffffff8143b872>] __generic_file_write_iter+0x352/0x540 mm/filemap.c:2866
 [<ffffffff81630ec7>] blkdev_write_iter+0x1b7/0x370 fs/block_dev.c:1718
 [<ffffffff8156e150>] vfs_iter_write+0x2e0/0x460 fs/read_write.c:390
 [<ffffffff81614efb>] iter_file_splice_write+0x5fb/0xb30 fs/splice.c:768
 [<ffffffff8160ff68>] do_splice_from fs/splice.c:870 [inline]
 [<ffffffff8160ff68>] direct_splice_actor+0x128/0x190 fs/splice.c:1037
 [<ffffffff816112b1>] splice_direct_to_actor+0x2c1/0x7e0 fs/splice.c:992
 [<ffffffff81611973>] do_splice_direct+0x1a3/0x270 fs/splice.c:1080
 [<ffffffff81573020>] do_sendfile+0x4f0/0xc60 fs/read_write.c:1393
 [<ffffffff81575201>] C_SYSC_sendfile fs/read_write.c:1469 [inline]
 [<ffffffff81575201>] compat_SyS_sendfile+0xd1/0x160 fs/read_write.c:1458
 [<ffffffff81006da7>] do_syscall_32_irqs_on arch/x86/entry/common.c:325 [inline]
 [<ffffffff81006da7>] do_fast_syscall_32+0x2f7/0x870 arch/x86/entry/common.c:387
 [<ffffffff838d6fd0>] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137

Showing all locks held in the system:
2 locks held by khungtaskd/515:
 #0:  (rcu_read_lock){......}, at: [<ffffffff813643ec>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff813643ec>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81423dc0>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3745:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838d3a72>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff820080d2>] n_tty_read+0x202/0x16b0 drivers/tty/n_tty.c:2133
3 locks held by kworker/u4:6/5565:
 #0:  ("writeback"){++++.+}, at: [<ffffffff8118ab5e>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("writeback"){++++.+}, at: [<ffffffff8118ab5e>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("writeback"){++++.+}, at: [<ffffffff8118ab5e>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("writeback"){++++.+}, at: [<ffffffff8118ab5e>] process_one_work+0x6ee/0x1500 kernel/workqueue.c:2085
 #1:  ((&(&wb->dwork)->work)){+.+.+.}, at: [<ffffffff8118ab98>] process_one_work+0x728/0x1500 kernel/workqueue.c:2089
 #2:  (&type->s_umount_key#29){.+.+..}, at: [<ffffffff8157a140>] trylock_super+0x20/0xf0 fs/super.c:393

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

NMI backtrace for cpu 1
CPU: 1 PID: 515 Comm: khungtaskd Not tainted 4.9.92-g4fb542f #2
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d976fd08 ffffffff81d9c509 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810b7d90 ffff8801d976fd40
 ffffffff81da7847 0000000000000001 0000000000000000 0000000000000002
Call Trace:
 [<ffffffff81d9c509>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d9c509>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81da7847>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81da77da>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b7e94>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81364984>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81364984>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81364984>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81364984>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119ab0d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838d5a9c>] 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: 0 Comm: swapper/0 Not tainted 4.9.92-g4fb542f #2
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffffffff84429880 task.stack: ffffffff84400000
RIP: 0010:[<ffffffff8135c716>] 
c [<ffffffff8135c716>] __read_once_size include/linux/compiler.h:243 [inline]
RIP: 0010:[<ffffffff8135c716>] 
c [<ffffffff8135c716>] check_kcov_mode kernel/kcov.c:68 [inline]
RIP: 0010:[<ffffffff8135c716>] 
c [<ffffffff8135c716>] __sanitizer_cov_trace_pc+0x26/0x50 kernel/kcov.c:100
RSP: 0018:ffff8801db207f88  EFLAGS: 00000046
RAX: ffffffff84429880 RBX: 000000000001a690 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff81e04049 RDI: ffffffff84407d18
RBP: ffff8801db207f88 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: ffffffff84a3a008 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000064a298 CR3: 00000001c39b8000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801db207f98
c ffffffff81e04049
c ffff8801db207fb8
c ffffffff81288455
c
 0000000000000000
c ffffffff84a2ae68
c ffff8801db207fd0
c ffffffff81148bba
c
 ffffffff84a2ae68
c ffff8801db207fe8
c ffffffff838d9ffa
c ffffffff84a2ae68
c
Call Trace:
 <IRQ> 
d [<ffffffff81e04049>] debug_smp_processor_id+0x9/0x20 lib/smp_processor_id.c:56
 [<ffffffff81288455>] rcu_irq_enter+0x15/0x120 kernel/rcu/tree.c:938
 [<ffffffff81148bba>] irq_enter+0xa/0xd0 kernel/softirq.c:338
 [<ffffffff838d9ffa>] smp_reschedule_interrupt+0xa/0x90 arch/x86/kernel/smp.c:267
 [<ffffffff838d7bd0>] reschedule_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:671
 <EOI> 
d [<ffffffff838d44d6>] ? native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:53
 [<ffffffff838d3b15>] arch_safe_halt arch/x86/include/asm/paravirt.h:104 [inline]
 [<ffffffff838d3b15>] default_idle+0x55/0x360 arch/x86/kernel/process.c:295
 [<ffffffff81069fa0>] arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:286
 [<ffffffff838d4935>] default_idle_call+0x45/0x60 kernel/sched/idle.c:97
 [<ffffffff81220725>] cpuidle_idle_call kernel/sched/idle.c:155 [inline]
 [<ffffffff81220725>] cpu_idle_loop kernel/sched/idle.c:248 [inline]
 [<ffffffff81220725>] cpu_startup_entry+0x2b5/0x380 kernel/sched/idle.c:303
 [<ffffffff838c179c>] rest_init+0x183/0x189 init/main.c:408
 [<ffffffff84a73943>] start_kernel+0x67e/0x6b2 init/main.c:663
 [<ffffffff84a7229a>] x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:196
 [<ffffffff84a723db>] x86_64_start_kernel+0x13f/0x162 arch/x86/kernel/head64.c:177
Code: 
c00 
c00 
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c55 
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c25 
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c65 
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c15 
ccc 
cb5 
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c00 
c01 
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c48 
c8b 
c75 
c08 
c75 
c2b 
c8b 
c90 
c78 
c12 
c00 
c00 
c<83> 
cfa 
c02 
c75 
c20 
c48 
c8b 
c88 
c80 
c12 
c00 
c00 
c8b 
c80 
c7c 
c12 
c00 
c00 
c48 
c8b 
c11 
c