INFO: task syz-executor2:4900 blocked for more than 140 seconds.
      Not tainted 4.9.143+ #75
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor2   D29832  4900   2118 0x00000004
 ffff8801a5a6df00 0000000000000000 ffff8801a50c5280 ffff8801da6b2f80
 ffff8801db721018 ffff8801bfe8fb48 ffffffff82808772 0000000000000001
 ffff8801a5a6e7b0 ffffed0034b4dcf5 00ff8801a5a6df00 ffff8801db7218f0
Call Trace:
 [<ffffffff82809c9f>] schedule+0x7f/0x1b0 kernel/sched/core.c:3553
 [<ffffffff8280a653>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3586
 [<ffffffff8280c6cd>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff8280c6cd>] mutex_lock_nested+0x38d/0x900 kernel/locking/mutex.c:621
 [<ffffffff81de9f46>] loop_control_ioctl+0x186/0x300 drivers/block/loop.c:1955
 [<ffffffff8154737c>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff8154737c>] file_ioctl fs/ioctl.c:493 [inline]
 [<ffffffff8154737c>] do_vfs_ioctl+0x1ac/0x11a0 fs/ioctl.c:677
 [<ffffffff815483ff>] SYSC_ioctl fs/ioctl.c:694 [inline]
 [<ffffffff815483ff>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 [<ffffffff810056ef>] do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285
 [<ffffffff82818a13>] 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: [<ffffffff8131c22c>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff8131c22c>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff813fe79f>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/2022:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff82816b02>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+.+.}, at: [<ffffffff81d37e32>] n_tty_read+0x202/0x1830 drivers/tty/n_tty.c:2156
2 locks held by syz-executor2/4900:
 #0:  (loop_index_mutex){+.+.+.}, at: [<ffffffff81de9e3a>] loop_control_ioctl+0x7a/0x300 drivers/block/loop.c:1941
 #1:  (&lo->lo_ctl_mutex#2){+.+.+.}, at: [<ffffffff81de9f46>] loop_control_ioctl+0x186/0x300 drivers/block/loop.c:1955
2 locks held by syz-executor0/4898:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff81de800c>] lo_ioctl+0x8c/0x1910 drivers/block/loop.c:1372
 #1:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff81b0c41e>] blkdev_reread_part+0x1e/0x40 block/ioctl.c:189
2 locks held by blkid/4902:
 #0:  (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff815c8f4c>] __blkdev_get+0x10c/0xd60 fs/block_dev.c:1268
 #1:  (loop_index_mutex){+.+.+.}, at: [<ffffffff81de1efb>] lo_open+0x1b/0xa0 drivers/block/loop.c:1589

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

NMI backtrace for cpu 0
CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.143+ #75
 ffff8801d9907d08 ffffffff81b43899 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff81098440 ffff8801d9907d40
 ffffffff81b4e9a9 0000000000000000 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81b43899>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81b43899>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81b4e9a9>] nmi_cpu_backtrace.cold.0+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81b4e93c>] nmi_trigger_cpumask_backtrace+0x12c/0x151 lib/nmi_backtrace.c:60
 [<ffffffff81098544>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff8131c7bd>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff8131c7bd>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff8131c7bd>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff8131c7bd>] watchdog+0x6ad/0xa20 kernel/hung_task.c:239
 [<ffffffff81142ccd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff82818bdc>] 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 0xffffffff82817646