INFO: task syz-executor0:2136 blocked for more than 140 seconds.
      Not tainted 4.9.149+ #5
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D25528  2136      1 0x00000004
 ffff8801cf8bc740 ffff8801cf290000 ffff8801db721000 ffff8801d1434740
 ffff8801db721018 ffff8801a7847538 ffffffff82805eb6 792b54079d5d57aa
 0000000000000000 ffff8801cf8bcff0 0000000000000006 ffff8801db7218f0
Call Trace:
 [<ffffffff82807442>] schedule+0x92/0x1c0 kernel/sched/core.c:3553
 [<ffffffff82807de3>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3586
 [<ffffffff82809d3d>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff82809d3d>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621
 [<ffffffff81dec586>] loop_probe+0x76/0x180 drivers/block/loop.c:1921
 [<ffffffff81db5301>] kobj_lookup+0x221/0x410 drivers/base/map.c:124
 [<ffffffff81b1799c>] get_gendisk+0x3c/0x2d0 block/genhd.c:716
 [<ffffffff815cb076>] __blkdev_get+0x356/0xd60 fs/block_dev.c:1262
 [<ffffffff815cdc58>] blkdev_get+0x2e8/0x920 fs/block_dev.c:1416
 [<ffffffff815ce4ba>] blkdev_open+0x1aa/0x250 fs/block_dev.c:1571
 [<ffffffff815035af>] do_dentry_open+0x3ef/0xc80 fs/open.c:766
 [<ffffffff81506f45>] vfs_open+0x105/0x230 fs/open.c:879
 [<ffffffff8153e305>] do_last fs/namei.c:3457 [inline]
 [<ffffffff8153e305>] path_openat+0xbf5/0x2f60 fs/namei.c:3581
 [<ffffffff81543451>] do_filp_open+0x1a1/0x280 fs/namei.c:3615
 [<ffffffff81507970>] do_sys_open+0x2f0/0x610 fs/open.c:1072
 [<ffffffff81507cbd>] SYSC_open fs/open.c:1090 [inline]
 [<ffffffff81507cbd>] SyS_open+0x2d/0x40 fs/open.c:1085
 [<ffffffff810056bd>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285
 [<ffffffff82816153>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/24:
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131b9bb>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131b9bb>] watchdog+0x11b/0xa40 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff813fe89b>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4336
2 locks held by getty/2038:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82814233>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff81d39e5e>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156
1 lock held by syz-executor0/2136:
 #0:  (loop_index_mutex){+.+.+.}, at: [<ffffffff81dec586>] loop_probe+0x76/0x180 drivers/block/loop.c:1921
1 lock held by syz-executor1/29882:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff815cbaab>] blkdev_put+0x2b/0x560 fs/block_dev.c:1621
2 locks held by syz-executor5/30096:
 #0:  (loop_index_mutex){+.+.+.}, at: [<ffffffff81dec70a>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1941
 #1:  (&lo->lo_ctl_mutex#2){+.+.+.}, at: [<ffffffff81dec80f>] loop_control_ioctl+0x17f/0x320 drivers/block/loop.c:1955
2 locks held by syz-executor2/30100:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff81dea8cf>] lo_ioctl+0x8f/0x1920 drivers/block/loop.c:1372
 #1:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff81b10dff>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189
2 locks held by syz-executor3/30097:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff815ca59b>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1579
 #1:  (loop_index_mutex){+.+.+.}, at: [<ffffffff81deed20>] lo_release+0x20/0x1b0 drivers/block/loop.c:1631
2 locks held by syz-executor1/30099:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff815cae2e>] __blkdev_get+0x10e/0xd60 fs/block_dev.c:1268
 #1:  (loop_index_mutex){+.+.+.}, at: [<ffffffff81de45cd>] lo_open+0x1d/0xb0 drivers/block/loop.c:1589
1 lock held by blkid/30105:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff815cbaab>] blkdev_put+0x2b/0x560 fs/block_dev.c:1621
2 locks held by blkid/30113:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff815cae2e>] __blkdev_get+0x10e/0xd60 fs/block_dev.c:1268
 #1:  (loop_index_mutex){+.+.+.}, at: [<ffffffff81de45cd>] lo_open+0x1d/0xb0 drivers/block/loop.c:1589

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

NMI backtrace for cpu 1
CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.149+ #5
 ffff8801d9907cd0 ffffffff81b47f01 0000000000000001 0000000000000000
 0000000000000001 ffffffff81097301 00000000003fffa3 ffff8801d9907d08
 ffffffff81b5318c 0000000000000001 0000000000000000 0000000000000001
Call Trace:
 [<ffffffff81b47f01>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81b47f01>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<ffffffff81b5318c>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81b53114>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60
 [<ffffffff81097494>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff8131be97>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff8131be97>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff8131be97>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff8131be97>] watchdog+0x5f7/0xa40 kernel/hung_task.c:239
 [<ffffffff81141e38>] kthread+0x278/0x310 kernel/kthread.c:211
 [<ffffffff8281631c>] 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 0xffffffff82814d42