INFO: task syz-executor7:14980 blocked for more than 120 seconds.
      Not tainted 4.15.0+ #298
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor7   D25200 14980   4188 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2845 [inline]
 __schedule+0x8eb/0x2060 kernel/sched/core.c:3421
 schedule+0xf5/0x430 kernel/sched/core.c:3480
 blk_mq_freeze_queue_wait+0x1bb/0x400 block/blk-mq.c:136
 blk_freeze_queue+0x4a/0x80 block/blk-mq.c:165
 blk_mq_freeze_queue+0x15/0x20 block/blk-mq.c:174
 loop_set_status+0x1a2/0xf60 drivers/block/loop.c:1097
 loop_set_status64+0x9d/0x110 drivers/block/loop.c:1271
 lo_ioctl+0xd86/0x1b70 drivers/block/loop.c:1381
 __blkdev_driver_ioctl block/ioctl.c:303 [inline]
 blkdev_ioctl+0x1759/0x1e00 block/ioctl.c:601
 block_ioctl+0xde/0x120 fs/block_dev.c:1860
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
 do_syscall_64+0x282/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x26/0x9b
RIP: 0033:0x453299
RSP: 002b:00007f4488a1cc58 EFLAGS: 00000212 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000453299
RDX: 0000000020a27f18 RSI: 0000000000004c04 RDI: 0000000000000014
RBP: 0000000000000271 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f2b38
R13: 00000000ffffffff R14: 00007f4488a1d6d4 R15: 0000000000000000

Showing all locks held in the system:
2 locks held by khungtaskd/758:
 #0:  (rcu_read_lock){....}, at: [<0000000068320434>] check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline]
 #0:  (rcu_read_lock){....}, at: [<0000000068320434>] watchdog+0x1c5/0xd60 kernel/hung_task.c:249
 #1:  (tasklist_lock){.+.+}, at: [<00000000cfc0a72e>] debug_show_all_locks+0xd3/0x3d0 kernel/locking/lockdep.c:4470
2 locks held by getty/4108:
 #0:  (&tty->ldisc_sem){++++}, at: [<000000009f454eda>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<00000000f0e6b0f7>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131
2 locks held by getty/4109:
 #0:  (&tty->ldisc_sem){++++}, at: [<000000009f454eda>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<00000000f0e6b0f7>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131
2 locks held by getty/4110:
 #0:  (&tty->ldisc_sem){++++}, at: [<000000009f454eda>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<00000000f0e6b0f7>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131
2 locks held by getty/4111:
 #0:  (&tty->ldisc_sem){++++}, at: [<000000009f454eda>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<00000000f0e6b0f7>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131
2 locks held by getty/4112:
 #0:  (&tty->ldisc_sem){++++}, at: [<000000009f454eda>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<00000000f0e6b0f7>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131
2 locks held by getty/4113:
 #0:  (&tty->ldisc_sem){++++}, at: [<000000009f454eda>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<00000000f0e6b0f7>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131
2 locks held by getty/4114:
 #0:  (&tty->ldisc_sem){++++}, at: [<000000009f454eda>] ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1:  (&ldata->atomic_read_lock){+.+.}, at: [<00000000f0e6b0f7>] n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131
1 lock held by syz-executor7/14980:
 #0:  (&lo->lo_ctl_mutex/1){+.+.}, at: [<00000000d88686c4>] lo_ioctl+0x8b/0x1b70 drivers/block/loop.c:1355
1 lock held by syz-executor7/14988:
 #0:  (&lo->lo_ctl_mutex/1){+.+.}, at: [<00000000d88686c4>] lo_ioctl+0x8b/0x1b70 drivers/block/loop.c:1355
1 lock held by blkid/14999:
 #0:  (&lo->lo_ctl_mutex/1){+.+.}, at: [<00000000d88686c4>] lo_ioctl+0x8b/0x1b70 drivers/block/loop.c:1355

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

NMI backtrace for cpu 1
CPU: 1 PID: 758 Comm: khungtaskd Not tainted 4.15.0+ #298
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:53
 nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103
 nmi_trigger_cpumask_backtrace+0x122/0x180 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_all_cpu_backtrace include/linux/nmi.h:138 [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+0x33c/0x400 kernel/kthread.c:238
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:429
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.15.0+ #298
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:native_apic_msr_eoi_write+0x0/0x20
RSP: 0018:ffff8801db407e98 EFLAGS: 00000046
RAX: dffffc0000000000 RBX: 1ffff1003b680fd4 RCX: 0000000000000000
RDX: 1ffffffff0d173ec RSI: 0000000000000000 RDI: 00000000000000b0
RBP: ffff8801db407fe8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff868b9f60
R13: ffff8801db407fc0 R14: ffffffff87268da0 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000c27000 CR3: 0000000006a22002 CR4: 00000000001606f0
Call Trace:
 <IRQ>
 reschedule_interrupt+0xa9/0xb0 arch/x86/entry/entry_64.S:849
 </IRQ>
RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54
RSP: 0018:ffffffff86a07c38 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff02
RAX: dffffc0000000000 RBX: 1ffffffff0d40f8a RCX: 0000000000000000
RDX: 1ffffffff0d59278 RSI: 0000000000000001 RDI: ffffffff86ac93c0
RBP: ffffffff86a07c38 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffffffff86a07cf0 R14: ffffffff87268da0 R15: 0000000000000000
 arch_safe_halt arch/x86/include/asm/paravirt.h:93 [inline]
 default_idle+0xbf/0x430 arch/x86/kernel/process.c:354
 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:345
 default_idle_call+0x36/0x90 kernel/sched/idle.c:98
 cpuidle_idle_call kernel/sched/idle.c:156 [inline]
 do_idle+0x24a/0x3b0 kernel/sched/idle.c:246
 cpu_startup_entry+0x104/0x120 kernel/sched/idle.c:351
 rest_init+0xed/0xf0 init/main.c:436
 start_kernel+0x7f1/0x819 init/main.c:716
 x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:378
 x86_64_start_kernel+0x77/0x7a arch/x86/kernel/head64.c:359
 secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:237
Code: ff e8 f5 df 79 00 48 8b 85 48 ff ff ff e9 23 ff ff ff e8 84 e0 79 00 e9 ee fe ff ff 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <55> 31 c0 b9 0b 08 00 00 89 c2 48 89 e5 0f 30 5d c3 0f 1f 44 00