INFO: task syz-executor938:3900 blocked for more than 120 seconds.
      Not tainted 4.4.132-g1d92c59 #49
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor938 D ffff8800ba88fa80 26368  3900   3898 0x00000000
 ffff8800ba88fa80 0000000000000246 0000000000000296 0000000041b58ab3
 ffffffff841e1300 ffff8801db31fdb8 ffff8801db31fde0 ffff8801db31f4d8
 ffff8801db31f4c0 ffff8801d45a8000 ffff8801d45ab000 0000000000000000
Call Trace:
 [<ffffffff838b222a>] schedule+0x7a/0x1b0 kernel/sched/core.c:3359
 [<ffffffff81da0ac0>] blk_mq_freeze_queue_wait+0x120/0x240 block/blk-mq.c:95
 [<ffffffff81da91bd>] blk_freeze_queue block/blk-mq.c:112 [inline]
 [<ffffffff81da91bd>] blk_mq_freeze_queue+0x1d/0x20 block/blk-mq.c:121
 [<ffffffff8251b302>] loop_switch drivers/block/loop.c:610 [inline]
 [<ffffffff8251b302>] loop_change_fd drivers/block/loop.c:696 [inline]
 [<ffffffff8251b302>] lo_ioctl+0x722/0x1ad0 drivers/block/loop.c:1361
 [<ffffffff81db7208>] __blkdev_driver_ioctl block/ioctl.c:288 [inline]
 [<ffffffff81db7208>] blkdev_ioctl+0x7b8/0x19c0 block/ioctl.c:584
 [<ffffffff815d362e>] block_ioctl+0xde/0x120 fs/block_dev.c:1625
 [<ffffffff8155946f>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff8155946f>] file_ioctl fs/ioctl.c:470 [inline]
 [<ffffffff8155946f>] do_vfs_ioctl+0x63f/0xf40 fs/ioctl.c:605
 [<ffffffff81559dff>] SYSC_ioctl fs/ioctl.c:622 [inline]
 [<ffffffff81559dff>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:613
 [<ffffffff838c0265>] entry_SYSCALL_64_fastpath+0x22/0x9e
1 lock held by syz-executor938/3900:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff8251ac6b>] lo_ioctl+0x8b/0x1ad0 drivers/block/loop.c:1355
Sending NMI to all CPUs:
NMI backtrace for cpu 0
CPU: 0 PID: 491 Comm: khungtaskd Not tainted 4.4.132-g1d92c59 #49
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8800bac81800 task.stack: ffff8800bac78000
RIP: 0010:[<ffffffff810bfe16>]  [<ffffffff810bfe16>] native_apic_mem_write arch/x86/include/asm/apic.h:94 [inline]
RIP: 0010:[<ffffffff810bfe16>]  [<ffffffff810bfe16>] __default_send_IPI_dest_field arch/x86/include/asm/ipi.h:119 [inline]
RIP: 0010:[<ffffffff810bfe16>]  [<ffffffff810bfe16>] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:61 [inline]
RIP: 0010:[<ffffffff810bfe16>]  [<ffffffff810bfe16>] flat_send_IPI_mask+0xf6/0x1a0 arch/x86/kernel/apic/apic_flat_64.c:69
RSP: 0018:ffff8800bac7fcc8  EFLAGS: 00000046
RAX: 0000000003000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fb300
RBP: ffff8800bac7fcf0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000246
R13: 0000000000000003 R14: 0000000000000002 R15: ffffffff8446f7a0
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007faee6f52000 CR3: 00000000b0ef0000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff8446f7a0 ffffffff84a18a60 0000000000000007 fffffbfff0942bfc
 0000000000000040 ffff8800bac7fd10 ffffffff810b5dd1 ffffffff83c0b1a0
 0000000000000003 ffff8800bac7fd68 ffffffff81e19023 ffffffff8140d9df
Call Trace:
 [<ffffffff810b5dd1>] nmi_raise_cpu_backtrace+0x61/0x80 arch/x86/kernel/apic/hw_nmi.c:33
 [<ffffffff81e19023>] nmi_trigger_all_cpu_backtrace.cold.4+0x70/0xad lib/nmi_backtrace.c:85
 [<ffffffff810b5e74>] arch_trigger_all_cpu_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 [<ffffffff8141a0c9>] trigger_all_cpu_backtrace include/linux/nmi.h:44 [inline]
 [<ffffffff8141a0c9>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff8141a0c9>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff8141a0c9>] watchdog.cold.1+0xd3/0xee kernel/hung_task.c:238
 [<ffffffff81190768>] kthread+0x268/0x300 kernel/kthread.c:211
 [<ffffffff838c0695>] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:510
Code: b3 5f ff f6 c4 10 75 e2 44 89 e8 c1 e0 18 89 04 25 10 b3 5f ff 44 89 f2 09 da 80 cf 04 41 83 fe 02 0f 44 d3 89 14 25 00 b3 5f ff <41> f7 c4 00 02 00 00 75 1a 4c 89 e7 57 9d 0f 1f 44 00 00 e8 f2 
NMI backtrace for cpu 1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.4.132-g1d92c59 #49
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d9a41800 task.stack: ffff8801d9a50000
RIP: 0010:[<ffffffff838c26d0>]  [<ffffffff838c26d0>] reschedule_interrupt+0x0/0xb0 arch/x86/entry/entry_64.S:763
RSP: 0018:ffff8801d9a57d78  EFLAGS: 00000046
RAX: 0000000000000007 RBX: ffffffff84a05b28 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff8801d9a420dc
RBP: ffff8801d9a57da0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000001 R14: fffffbfff074890c R15: ffffffff84a05b28
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000021c4000 CR3: 00000000b0ef0000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff810cc306 0000000000000010 0000000000000246 ffff8801d9a57da0
 0000000000000018 ffff8801d9a57dd8 ffffffff81025da5 ffff8801d9a58000
 0000000000000000 0000000000000000 fffffbfff074890c ffffffff84a05b28
Call Trace:
 [<ffffffff81025da5>] arch_safe_halt arch/x86/include/asm/paravirt.h:117 [inline]
 [<ffffffff81025da5>] default_idle+0x55/0x3c0 arch/x86/kernel/process.c:290
 [<ffffffff810272f0>] arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:281
 [<ffffffff8121b9e7>] default_idle_call+0x57/0x70 kernel/sched/idle.c:93
 [<ffffffff8121c18f>] cpuidle_idle_call kernel/sched/idle.c:157 [inline]
 [<ffffffff8121c18f>] cpu_idle_loop kernel/sched/idle.c:253 [inline]
 [<ffffffff8121c18f>] cpu_startup_entry+0x6af/0x780 kernel/sched/idle.c:301
 [<ffffffff810aa1e4>] start_secondary+0x324/0x400 arch/x86/kernel/smpboot.c:242
Code: 04 25 94 66 01 00 65 48 0f 44 24 25 98 66 01 00 57 e8 5e 09 74 fd e8 70 58 7e fd e9 1b e7 ff ff 90 66 2e 0f 1f 84 00 00 00 00 00 <0f> 1f 00 68 02 ff ff ff fc 48 83 c4 88 4c 89 5c 24 30 4c 89 54