kworker/dying (66) used greatest stack depth: 12080 bytes left
INFO: task syz-executor5:10774 blocked for more than 120 seconds.
      Not tainted 4.14.0-rc2-next-20170929+ #32
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor5   D23120 10774  10451 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2795 [inline]
 __schedule+0x8e8/0x2070 kernel/sched/core.c:3374
 schedule+0xf5/0x430 kernel/sched/core.c:3433
 io_schedule+0x1c/0x70 kernel/sched/core.c:5041
 wait_on_page_bit_common+0x4b3/0x770 mm/filemap.c:1002
 wait_on_page_bit mm/filemap.c:1035 [inline]
 wait_on_page_writeback include/linux/pagemap.h:541 [inline]
 __filemap_fdatawait_range+0x2b3/0x460 mm/filemap.c:436
 filemap_fdatawait_keep_errors+0x2a/0xb0 mm/filemap.c:503
 fdatawait_one_bdev+0x50/0x70 fs/sync.c:94
 iterate_bdevs+0x109/0x260 fs/block_dev.c:2157
 sys_sync+0x122/0x1c0 fs/sync.c:116
 entry_SYSCALL_64_fastpath+0x1f/0xbe
RIP: 0033:0x4520a9
RSP: 002b:00007fe3563c7c08 EFLAGS: 00000216 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 0000000000718000 RCX: 00000000004520a9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000086 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000216 R12: 0000000000000000
R13: 0000000000a6f7ef R14: 00007fe3563c89c0 R15: 0000000000000000

Showing all locks held in the system:
2 locks held by khungtaskd/644:
 #0:  (rcu_read_lock){....}, at: [<ffffffff81705415>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline]
 #0:  (rcu_read_lock){....}, at: [<ffffffff81705415>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249
 #1:  (tasklist_lock){.+.?}, at: [<ffffffff81550f23>] debug_show_all_locks+0xd3/0x400 kernel/locking/lockdep.c:4552
1 lock held by rsyslogd/2870:
 #0:  (&f->f_pos_lock){+.+.}, at: [<ffffffff81b3ecd1>] __fdget_pos+0x131/0x1a0 fs/file.c:767
2 locks held by getty/2952:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff84d74237>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8271bb12>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2133
2 locks held by getty/2953:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff84d74237>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8271bb12>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2133
2 locks held by getty/2954:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff84d74237>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8271bb12>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2133
2 locks held by getty/2955:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff84d74237>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8271bb12>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2133
2 locks held by getty/2956:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff84d74237>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8271bb12>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2133
2 locks held by getty/2957:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff84d74237>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8271bb12>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2133
2 locks held by getty/2958:
 #0:  (&tty->ldisc_sem){++++}, at: [<ffffffff84d74237>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<ffffffff8271bb12>] n_tty_read+0x2f2/0x1a10 drivers/tty/n_tty.c:2133
3 locks held by kworker/u4:7/3868:
 #0:  ("writeback"){+.+.}, at: [<ffffffff81472ea4>] __write_once_size include/linux/compiler.h:305 [inline]
 #0:  ("writeback"){+.+.}, at: [<ffffffff81472ea4>] atomic64_set arch/x86/include/asm/atomic64_64.h:33 [inline]
 #0:  ("writeback"){+.+.}, at: [<ffffffff81472ea4>] atomic_long_set include/asm-generic/atomic-long.h:56 [inline]
 #0:  ("writeback"){+.+.}, at: [<ffffffff81472ea4>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("writeback"){+.+.}, at: [<ffffffff81472ea4>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("writeback"){+.+.}, at: [<ffffffff81472ea4>] process_one_work+0xad4/0x1bd0 kernel/workqueue.c:2090
 #1:  ((&(&wb->dwork)->work)){+.+.}, at: [<ffffffff81472efc>] process_one_work+0xb2c/0x1bd0 kernel/workqueue.c:2094
 #2:  (&type->s_umount_key#30){++++}, at: [<ffffffff81ac8e40>] trylock_super+0x20/0x100 fs/super.c:391
3 locks held by kworker/u4:8/4185:
 #0:  ("%s""netns"){+.+.}, at: [<ffffffff81472ea4>] __write_once_size include/linux/compiler.h:305 [inline]
 #0:  ("%s""netns"){+.+.}, at: [<ffffffff81472ea4>] atomic64_set arch/x86/include/asm/atomic64_64.h:33 [inline]
 #0:  ("%s""netns"){+.+.}, at: [<ffffffff81472ea4>] atomic_long_set include/asm-generic/atomic-long.h:56 [inline]
 #0:  ("%s""netns"){+.+.}, at: [<ffffffff81472ea4>] set_work_data kernel/workqueue.c:617 [inline]
 #0:  ("%s""netns"){+.+.}, at: [<ffffffff81472ea4>] set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0:  ("%s""netns"){+.+.}, at: [<ffffffff81472ea4>] process_one_work+0xad4/0x1bd0 kernel/workqueue.c:2090
 #1:  (net_cleanup_work){+.+.}, at: [<ffffffff81472efc>] process_one_work+0xb2c/0x1bd0 kernel/workqueue.c:2094
 #2:  (net_mutex){+.+.}, at: [<ffffffff83e7a397>] cleanup_net+0x247/0xb60 net/core/net_namespace.c:449
1 lock held by blkid/10449:
 #0:  (&bdev->bd_mutex){+.+.}, at: [<ffffffff81bbd18a>] blkdev_put+0x2a/0x4f0 fs/block_dev.c:1803
1 lock held by syz-executor5/10774:
 #0:  (&bdev->bd_mutex){+.+.}, at: [<ffffffff81bc12a8>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2155
1 lock held by syz-executor5/10800:
 #0:  (&bdev->bd_mutex){+.+.}, at: [<ffffffff81bc12a8>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2155
1 lock held by syz-executor7/10820:
 #0:  (&bdev->bd_mutex){+.+.}, at: [<ffffffff81bc12a8>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2155
1 lock held by syz-executor7/10833:
 #0:  (&bdev->bd_mutex){+.+.}, at: [<ffffffff81bc12a8>] iterate_bdevs+0xc8/0x260 fs/block_dev.c:2155

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

NMI backtrace for cpu 1
CPU: 1 PID: 644 Comm: khungtaskd Not tainted 4.14.0-rc2-next-20170929+ #32
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:16 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:52
 nmi_cpu_backtrace+0x20e/0x240 lib/nmi_backtrace.c:102
 nmi_trigger_cpumask_backtrace+0x122/0x180 lib/nmi_backtrace.c:61
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 trigger_all_cpu_backtrace include/linux/nmi.h:135 [inline]
 check_hung_task kernel/hung_task.c:132 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline]
 watchdog+0x90c/0xd60 kernel/hung_task.c:249
 kthread+0x3c9/0x4b0 kernel/kthread.c:242
 ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff84d74ea6