VFS: Dirty inode writeback failed for block device loop0 (err=-5).
IPVS: Creating netns size=2536 id=68
Buffer I/O error on dev loop0, logical block 0, lost async page write
Buffer I/O error on dev loop0, logical block 0, lost async page write
Buffer I/O error on dev loop0, logical block 16, async page read
INFO: task syz-executor7:16415 blocked for more than 120 seconds.
      Not tainted 4.9.92-g9c3fb9c #10
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor7   D26424 16415  16248 0x20020004
 ffff8801b843e000 ffff880193724fc0 ffff880193724fc0 ffff8801d8936000
 ffff8801db321b98 ffff8801c863ef80 ffffffff838a76cb 0000000041b58ab3
 ffffffff84193da8 00ffffff8123ac80 ffff8801db322468 ffff8801db322490
Call Trace:
 [<ffffffff838a8c6f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3551
 [<ffffffff838b4c2c>] schedule_timeout+0x56c/0x10b0 kernel/time/timer.c:1768
 [<ffffffff838a6e7e>] io_schedule_timeout+0x1be/0x390 kernel/sched/core.c:5173
 [<ffffffff838aa0e9>] io_schedule include/linux/sched.h:460 [inline]
 [<ffffffff838aa0e9>] bit_wait_io+0x19/0xa0 kernel/sched/wait.c:582
 [<ffffffff838a9952>] __wait_on_bit_lock+0xc2/0x1c0 kernel/sched/wait.c:421
 [<ffffffff8143202f>] __lock_page+0xff/0x160 mm/filemap.c:934
 [<ffffffff8145b8e3>] lock_page include/linux/pagemap.h:454 [inline]
 [<ffffffff8145b8e3>] write_cache_pages+0x833/0xec0 mm/page-writeback.c:2214
 [<ffffffff8145c04a>] generic_writepages+0xda/0x150 mm/page-writeback.c:2333
 [<ffffffff8162ab4d>] blkdev_writepages+0x1d/0x30 fs/block_dev.c:1764
 [<ffffffff8145ea0d>] do_writepages+0xed/0x1c0 mm/page-writeback.c:2347
 [<ffffffff8143a5b3>] __filemap_fdatawrite_range+0x1b3/0x250 mm/filemap.c:390
 [<ffffffff8143a869>] filemap_write_and_wait_range+0x59/0xb0 mm/filemap.c:580
 [<ffffffff81629e96>] blkdev_fsync+0x66/0xb0 fs/block_dev.c:369
 [<ffffffff816157ea>] vfs_fsync_range+0x10a/0x250 fs/sync.c:195
 [<ffffffff8162ca66>] generic_write_sync include/linux/fs.h:2590 [inline]
 [<ffffffff8162ca66>] blkdev_write_iter+0x2a6/0x380 fs/block_dev.c:1720
 [<ffffffff8156d500>] vfs_iter_write+0x2e0/0x450 fs/read_write.c:390
 [<ffffffff81612765>] iter_file_splice_write+0x5b5/0xb60 fs/splice.c:768
 [<ffffffff8160d5a5>] do_splice_from fs/splice.c:870 [inline]
 [<ffffffff8160d5a5>] direct_splice_actor+0x125/0x180 fs/splice.c:1037
 [<ffffffff8160eb6c>] splice_direct_to_actor+0x2cc/0x800 fs/splice.c:992
 [<ffffffff8160f247>] do_splice_direct+0x1a7/0x270 fs/splice.c:1080
 [<ffffffff8157221b>] do_sendfile+0x54b/0xd30 fs/read_write.c:1393
 [<ffffffff815742d1>] C_SYSC_sendfile fs/read_write.c:1469 [inline]
 [<ffffffff815742d1>] compat_SyS_sendfile+0xd1/0x160 fs/read_write.c:1458
 [<ffffffff81006f95>] do_syscall_32_irqs_on arch/x86/entry/common.c:325 [inline]
 [<ffffffff81006f95>] do_fast_syscall_32+0x2f5/0x870 arch/x86/entry/common.c:387
 [<ffffffff838b9c90>] 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: [<ffffffff813722b5>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff813722b5>] watchdog+0x125/0xa70 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81236de0>] debug_show_all_locks+0x70/0x280 kernel/locking/lockdep.c:4336
2 locks held by getty/3749:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff838b67a2>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff8200a8f4>] n_tty_read+0x1f4/0x16c0 drivers/tty/n_tty.c:2133
3 locks held by kworker/u4:4/5290:
 #0:  ("writeback"){++++.+}, at: [<ffffffff8118b0d2>] work_static include/linux/workqueue.h:186 [inline]
 #0:  ("writeback"){++++.+}, at: [<ffffffff8118b0d2>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("writeback"){++++.+}, at: [<ffffffff8118b0d2>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("writeback"){++++.+}, at: [<ffffffff8118b0d2>] process_one_work+0x6f2/0x1610 kernel/workqueue.c:2085
 #1:  ((&(&wb->dwork)->work)){+.+.+.}, at: [<ffffffff8118b10c>] process_one_work+0x72c/0x1610 kernel/workqueue.c:2089
 #2:  (&type->s_umount_key#28){++++..}, at: [<ffffffff815792b0>] trylock_super+0x20/0x100 fs/super.c:393

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

NMI backtrace for cpu 1
CPU: 1 PID: 515 Comm: khungtaskd Not tainted 4.9.92-g9c3fb9c #10
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d86efd00 ffffffff81d95109 0000000000000000 0000000000000001
 0000000000000001 0000000000000001 ffffffff810bb8f0 ffff8801d86efd38
 ffffffff81da025d 0000000000000001 0000000000000000 ffff8801b843cc18
Call Trace:
 [<ffffffff81d95109>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d95109>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81da025d>] nmi_cpu_backtrace+0xfd/0x120 lib/nmi_backtrace.c:99
 [<ffffffff81da0397>] nmi_trigger_cpumask_backtrace+0x117/0x190 lib/nmi_backtrace.c:60
 [<ffffffff810bb9e4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81372880>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81372880>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81372880>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81372880>] watchdog+0x6f0/0xa70 kernel/hung_task.c:239
 [<ffffffff8119c0dd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff838b875c>] 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 skipped: idling at pc 0xffffffff838b7216