INFO: task syz-executor4:15740 blocked for more than 140 seconds.
      Not tainted 4.18.0-rc3-next-20180706+ #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor4   D21904 15740   4460 0x80000004
Call Trace:
 context_switch kernel/sched/core.c:2853 [inline]
 __schedule+0x87c/0x1ed0 kernel/sched/core.c:3501
 schedule+0xfb/0x450 kernel/sched/core.c:3545
 io_schedule+0x1c/0x70 kernel/sched/core.c:5168
 wait_on_page_bit_common mm/filemap.c:1079 [inline]
 __lock_page+0x5a7/0x790 mm/filemap.c:1252
 lock_page include/linux/pagemap.h:483 [inline]
 pagecache_get_page+0x856/0xe40 mm/filemap.c:1516
 grab_cache_page_write_begin+0x6f/0xa0 mm/filemap.c:2985
 block_write_begin+0xae/0x370 fs/buffer.c:2072
 blkdev_write_begin+0x3c/0x50 fs/block_dev.c:584
 generic_perform_write+0x3ae/0x6c0 mm/filemap.c:3035
 __generic_file_write_iter+0x26e/0x630 mm/filemap.c:3160
 blkdev_write_iter+0x23f/0x450 fs/block_dev.c:1913
 call_write_iter include/linux/fs.h:1822 [inline]
 do_iter_readv_writev+0x897/0xa90 fs/read_write.c:680
 do_iter_write+0x185/0x5f0 fs/read_write.c:959
 vfs_iter_write+0x77/0xb0 fs/read_write.c:972
 iter_file_splice_write+0x8e7/0x1010 fs/splice.c:750
 do_splice_from fs/splice.c:852 [inline]
 direct_splice_actor+0x128/0x190 fs/splice.c:1019
 splice_direct_to_actor+0x318/0x8f0 fs/splice.c:974
 do_splice_direct+0x2d4/0x420 fs/splice.c:1062
 do_sendfile+0x62a/0xe20 fs/read_write.c:1440
 __do_sys_sendfile64 fs/read_write.c:1495 [inline]
 __se_sys_sendfile64 fs/read_write.c:1487 [inline]
 __x64_sys_sendfile64+0x15d/0x250 fs/read_write.c:1487
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x455e29
Code: cc 64 48 8b 0c 25 f8 ff ff ff 48 3b 61 10 0f 86 ab 04 00 00 48 83 ec 58 48 89 6c 24 50 48 8d 6c 24 50 48 8b 44 24 60 c6 00 00 <48> 8b 4c 24 68 48 89 ca 48 89 50 08 48 8b 59 20 48 01 da 31 db 31 
RSP: 002b:00007f9186a75c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f9186a766d4 RCX: 0000000000455e29
RDX: 0000000020000040 RSI: 0000000000000014 RDI: 0000000000000013
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0020000102000007 R11: 0000000000000246 R12: 0000000000000016
R13: 00000000004c1113 R14: 00000000004d1540 R15: 0000000000000003
INFO: lockdep is turned off.
NMI backtrace for cpu 0
CPU: 0 PID: 897 Comm: khungtaskd Not tainted 4.18.0-rc3-next-20180706+ #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113
 nmi_cpu_backtrace.cold.5+0x19/0xce lib/nmi_backtrace.c:103
 nmi_trigger_cpumask_backtrace+0x151/0x192 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_all_cpu_backtrace include/linux/nmi.h:143 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:204 [inline]
 watchdog+0xb39/0x10b0 kernel/hung_task.c:265
 kthread+0x345/0x410 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:415
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 15746 Comm: loop0 Not tainted 4.18.0-rc3-next-20180706+ #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:compound_head include/linux/page-flags.h:142 [inline]
RIP: 0010:PageLocked include/linux/page-flags.h:272 [inline]
RIP: 0010:unlock_page+0x110/0x2c0 mm/filemap.c:1184
Code: 89 ee e8 c3 51 e3 ff 4d 85 ed 0f 85 45 01 00 00 e8 85 50 e3 ff 4d 8d 6e c0 48 b8 00 00 00 00 00 fc ff df 4c 89 ea 48 c1 ea 03 <c6> 04 02 00 4c 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 3d 01 00 00 4c 
RSP: 0018:ffff88019a3668a0 EFLAGS: 00000a06
RAX: dffffc0000000000 RBX: ffffea0006e633c0 RCX: ffffffff819929cd
RDX: 1ffff1003346cd21 RSI: ffffffff819929db RDI: 0000000000000007
RBP: ffff88019a366970 R08: ffff8801c7e7c6c0 R09: ffffed003346ccc5
R10: ffffed003346ccc5 R11: 0000000000000003 R12: 1ffff1003346cd15
R13: ffff88019a366908 R14: ffff88019a366948 R15: ffffea0006e633c8
FS:  0000000000000000(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffff600400 CR3: 00000001af7d4000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 find_lock_entry+0x37c/0x8c0 mm/filemap.c:1462
 shmem_getpage_gfp+0x3cd/0x3ec0 mm/shmem.c:1610
 shmem_getpage mm/shmem.c:132 [inline]
 shmem_file_read_iter+0x399/0x1090 mm/shmem.c:2433
 call_read_iter include/linux/fs.h:1816 [inline]
 do_iter_readv_writev+0x790/0xa90 fs/read_write.c:678
 do_iter_read+0x26e/0x650 fs/read_write.c:922
 vfs_iter_read+0x77/0xb0 fs/read_write.c:936
 lo_read_simple drivers/block/loop.c:350 [inline]
 do_req_filebacked drivers/block/loop.c:615 [inline]
 loop_handle_cmd drivers/block/loop.c:1786 [inline]
 loop_queue_work+0x9ce/0x3afc drivers/block/loop.c:1800
 kthread_worker_fn+0x35f/0xa50 kernel/kthread.c:656
 loop_kthread_worker_fn+0x51/0x60 drivers/block/loop.c:892
 kthread+0x345/0x410 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:415
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.128 msecs