device lo entered promiscuous mode
INFO: task syz-executor0:3875 blocked for more than 120 seconds.
      Not tainted 4.9.98-g9731a2d #19
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D26616  3875   3867 0x00000000
 ffff88019ac79800 ffff8801cec28a80 ffff8801b7350540 ffff8801cfa23000
 ffff8801db321b98 ffff88019a4bf4e8 ffffffff839e377d ffff88019ac7a0c8
 ffffed003358f418 ffff88019ac79800 00fffc0000000000 ffff8801db322468
Call Trace:
 [<ffffffff839e4d7f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff839e5703>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3590
 [<ffffffff839e9b86>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff839e9b86>] mutex_lock_nested+0x326/0x870 kernel/locking/mutex.c:621
 [<ffffffff825c9ff4>] loop_probe+0x74/0x180 drivers/block/loop.c:1886
 [<ffffffff8256f383>] kobj_lookup+0x223/0x410 drivers/base/map.c:124
 [<ffffffff81e57d99>] get_gendisk+0x39/0x2d0 block/genhd.c:716
 [<ffffffff8162eb41>] __blkdev_get+0x351/0xd60 fs/block_dev.c:1262
 [<ffffffff81631dea>] blkdev_get+0x2da/0x920 fs/block_dev.c:1416
 [<ffffffff81632645>] blkdev_open+0x1a5/0x250 fs/block_dev.c:1571
 [<ffffffff81567443>] do_dentry_open+0x703/0xc80 fs/open.c:766
 [<ffffffff8156ac2c>] vfs_open+0x11c/0x210 fs/open.c:879
 [<ffffffff815a1d68>] do_last fs/namei.c:3410 [inline]
 [<ffffffff815a1d68>] path_openat+0x758/0x3590 fs/namei.c:3534
 [<ffffffff815a8e67>] do_filp_open+0x197/0x270 fs/namei.c:3568
 [<ffffffff8156b63d>] do_sys_open+0x30d/0x5c0 fs/open.c:1072
 [<ffffffff8156b91d>] SYSC_open fs/open.c:1090 [inline]
 [<ffffffff8156b91d>] SyS_open+0x2d/0x40 fs/open.c:1085
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f4653>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/519:
 #0:  (rcu_read_lock){......}, at: [<ffffffff813646ec>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff813646ec>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81423ba0>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3777:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f2822>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211cc12>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
1 lock held by syz-executor0/3875:
 #0:  (loop_index_mutex){+.+.+.}, at: [<ffffffff825c9ff4>] loop_probe+0x74/0x180 drivers/block/loop.c:1886
2 locks held by syz-executor7/7524:
 #0:  (loop_index_mutex){+.+.+.}, at: [<ffffffff825c9cfa>] loop_control_ioctl+0x7a/0x300 drivers/block/loop.c:1906
 #1:  (&lo->lo_ctl_mutex#2){+.+.+.}, at: [<ffffffff825c9e06>] loop_control_ioctl+0x186/0x300 drivers/block/loop.c:1920
2 locks held by syz-executor7/7551:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff8162e8fc>] __blkdev_get+0x10c/0xd60 fs/block_dev.c:1268
 #1:  (loop_index_mutex){+.+.+.}, at: [<ffffffff825c27bb>] lo_open+0x1b/0xa0 drivers/block/loop.c:1555
1 lock held by syz-executor7/7559:
 #0:  (loop_index_mutex){+.+.+.}, at: [<ffffffff825c9cfa>] loop_control_ioctl+0x7a/0x300 drivers/block/loop.c:1906
1 lock held by syz-executor7/7572:
 #0:  (loop_index_mutex){+.+.+.}, at: [<ffffffff825c9cfa>] loop_control_ioctl+0x7a/0x300 drivers/block/loop.c:1906
1 lock held by syz-executor7/7573:
 #0:  (loop_index_mutex){+.+.+.}, at: [<ffffffff825c9cfa>] loop_control_ioctl+0x7a/0x300 drivers/block/loop.c:1906
1 lock held by syz-executor7/7574:
 #0:  (loop_index_mutex){+.+.+.}, at: [<ffffffff825c9cfa>] loop_control_ioctl+0x7a/0x300 drivers/block/loop.c:1906
1 lock held by syz-executor7/7575:
 #0:  (loop_index_mutex){+.+.+.}, at: [<ffffffff825c9cfa>] loop_control_ioctl+0x7a/0x300 drivers/block/loop.c:1906
1 lock held by syz-executor7/7576:
 #0:  (loop_index_mutex){+.+.+.}, at: [<ffffffff825c9cfa>] loop_control_ioctl+0x7a/0x300 drivers/block/loop.c:1906
1 lock held by syz-executor7/7578:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff8162e8fc>] __blkdev_get+0x10c/0xd60 fs/block_dev.c:1268
2 locks held by syz-executor5/7555:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c771b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
 #1:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff81e5356e>] blkdev_reread_part+0x1e/0x40 block/ioctl.c:189
1 lock held by syz-executor5/7580:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff8162e8fc>] __blkdev_get+0x10c/0xd60 fs/block_dev.c:1268
1 lock held by syz-executor6/7554:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff8162f57a>] blkdev_put+0x2a/0x560 fs/block_dev.c:1621
1 lock held by syz-executor6/7583:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff8162e8fc>] __blkdev_get+0x10c/0xd60 fs/block_dev.c:1268
2 locks held by blkid/7565:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff8162e8fc>] __blkdev_get+0x10c/0xd60 fs/block_dev.c:1268
 #1:  (loop_index_mutex){+.+.+.}, at: [<ffffffff825c27bb>] lo_open+0x1b/0xa0 drivers/block/loop.c:1555
2 locks held by blkid/7567:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff8162e8fc>] __blkdev_get+0x10c/0xd60 fs/block_dev.c:1268
 #1:  (loop_index_mutex){+.+.+.}, at: [<ffffffff825c27bb>] lo_open+0x1b/0xa0 drivers/block/loop.c:1555

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

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.98-g9731a2d #19
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d97afd08 ffffffff81eb0ee9 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b7da0 ffff8801d97afd40
 ffffffff81ebc1e7 0000000000000000 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb0ee9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb0ee9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebc1e7>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebc17a>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b7ea4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81364c84>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81364c84>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81364c84>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81364c84>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119ad5d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f481c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at pc 0xffffffff839f3286