INFO: task syz-executor2:12053 blocked for more than 120 seconds.
      Not tainted 4.4.124-g851fb4d #60
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor2   D ffff8801cd41fa80 30040 12053   8048 0x00000004
 ffff8801cd41fa80 0000000000000246 0000000000000296 0000000041b58ab3
 ffffffff83fabb00 ffff8801db21fdb8 ffff8801db21fde0 ffff8801db21f4d8
 ffff8801db21f4c0 ffff8800b9944800 ffff8801d1db1800 0000000000000000
Call Trace:
 [<ffffffff8376b59a>] schedule+0x7a/0x1b0 kernel/sched/core.c:3359
 [<ffffffff81c989e0>] blk_mq_freeze_queue_wait+0x120/0x240 block/blk-mq.c:95
 [<ffffffff81ca0f5d>] blk_freeze_queue block/blk-mq.c:112 [inline]
 [<ffffffff81ca0f5d>] blk_mq_freeze_queue+0x1d/0x20 block/blk-mq.c:121
 [<ffffffff82422e8f>] loop_switch drivers/block/loop.c:610 [inline]
 [<ffffffff82422e8f>] loop_change_fd drivers/block/loop.c:693 [inline]
 [<ffffffff82422e8f>] lo_ioctl+0xfef/0x19c0 drivers/block/loop.c:1354
 [<ffffffff81caeb5b>] __blkdev_driver_ioctl block/ioctl.c:288 [inline]
 [<ffffffff81caeb5b>] blkdev_ioctl+0x4ab/0x1990 block/ioctl.c:584
 [<ffffffff815d256e>] block_ioctl+0xde/0x120 fs/block_dev.c:1625
 [<ffffffff8155a58a>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff8155a58a>] do_vfs_ioctl+0x7aa/0xee0 fs/ioctl.c:607
 [<ffffffff8155ad4f>] SYSC_ioctl fs/ioctl.c:622 [inline]
 [<ffffffff8155ad4f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:613
 [<ffffffff837796e5>] entry_SYSCALL_64_fastpath+0x22/0x9e
1 lock held by syz-executor2/12053:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff82421f2f>] lo_ioctl+0x8f/0x19c0 drivers/block/loop.c:1348
Sending NMI to all CPUs:
NMI backtrace for cpu 0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.4.124-g851fb4d #60
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffffffff84217840 task.stack: ffffffff84200000
RIP: 0010:[<ffffffff8377bb90>]  [<ffffffff8377bb90>] reschedule_interrupt+0x0/0xb0 arch/x86/entry/entry_64.S:763
RSP: 0018:ffffffff84207d98  EFLAGS: 00000046
RAX: 0000000000000007 RBX: ffffffff847deac8 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffffff8421811c
RBP: ffffffff84207dc0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: fffffbfff07088c0 R14: ffffffff847ece38 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5c680569b8 CR3: 00000001d1cf0000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff810d0666 0000000000000010 0000000000000246 ffffffff84207dc0
 0000000000000018 ffffffff84207df8 ffffffff81027e85 ffffffff84208000
 ffffffff847deac8 fffffbfff07088c0 ffffffff847ece38 0000000000000000
Call Trace:
 [<ffffffff81027e85>] arch_safe_halt arch/x86/include/asm/paravirt.h:117 [inline]
 [<ffffffff81027e85>] default_idle+0x55/0x3c0 arch/x86/kernel/process.c:290
 [<ffffffff810293fa>] arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:281
 [<ffffffff812217c8>] default_idle_call+0x48/0x70 kernel/sched/idle.c:93
 [<ffffffff81221ecd>] cpuidle_idle_call kernel/sched/idle.c:157 [inline]
 [<ffffffff81221ecd>] cpu_idle_loop kernel/sched/idle.c:253 [inline]
 [<ffffffff81221ecd>] cpu_startup_entry+0x5fd/0x8f0 kernel/sched/idle.c:301
 [<ffffffff83766529>] rest_init+0x189/0x190 init/main.c:410
 [<ffffffff84823811>] start_kernel+0x6b9/0x6ee init/main.c:682
 [<ffffffff84822312>] x86_64_start_reservations+0x2a/0x2c arch/x86/kernel/head64.c:196
 [<ffffffff84822454>] x86_64_start_kernel+0x140/0x163 arch/x86/kernel/head64.c:185
Code: 04 25 94 66 01 00 65 48 0f 44 24 25 98 66 01 00 57 e8 9e 74 88 fd e8 10 00 93 fd e9 db e6 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 
NMI backtrace for cpu 1
CPU: 1 PID: 486 Comm: khungtaskd Not tainted 4.4.124-g851fb4d #60
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8800bac13000 task.stack: ffff8800bac48000
RIP: 0010:[<ffffffff810c3fa7>]  [<ffffffff810c3fa7>] native_apic_mem_write arch/x86/include/asm/apic.h:94 [inline]
RIP: 0010:[<ffffffff810c3fa7>]  [<ffffffff810c3fa7>] __default_send_IPI_dest_field arch/x86/include/asm/ipi.h:119 [inline]
RIP: 0010:[<ffffffff810c3fa7>]  [<ffffffff810c3fa7>] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:61 [inline]
RIP: 0010:[<ffffffff810c3fa7>]  [<ffffffff810c3fa7>] flat_send_IPI_mask+0xf7/0x1a0 arch/x86/kernel/apic/apic_flat_64.c:69
RSP: 0018:ffff8800bac4fcb8  EFLAGS: 00000046
RAX: 0000000003000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fb300
RBP: ffff8800bac4fce0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000246
R13: 0000000000000003 R14: ffffffff8426f5a0 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1ca227a000 CR3: 00000001cc388000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff8426f5a0 ffffffff847f09c0 fffffbfff08fdbec dffffc0000000000
 ffff8801db31bca0 ffff8800bac4fd00 ffffffff810b9adb ffffffff839f6e40
 0000000000000003 ffff8800bac4fd60 ffffffff81d115a4 ffffffff8141b803
Call Trace:
 [<ffffffff810b9adb>] nmi_raise_cpu_backtrace+0x5b/0x70 arch/x86/kernel/apic/hw_nmi.c:33
 [<ffffffff81d115a4>] nmi_trigger_all_cpu_backtrace+0x4a4/0x550 lib/nmi_backtrace.c:85
 [<ffffffff810b9b74>] arch_trigger_all_cpu_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 [<ffffffff8136944a>] trigger_all_cpu_backtrace include/linux/nmi.h:44 [inline]
 [<ffffffff8136944a>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff8136944a>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff8136944a>] watchdog+0x6fa/0xae0 kernel/hung_task.c:238
 [<ffffffff811909c8>] kthread+0x268/0x300 kernel/kthread.c:211
 [<ffffffff83779b15>] ret_from_fork+0x55/0x80 arch/x86/entry/entry_64.S:510
Code: b3 5f ff f6 c4 10 75 e1 44 89 e8 c1 e0 18 89 04 25 10 b3 5f ff 44 89 fa 09 da 80 cf 04 41 83 ff 02 0f 44 d3 89 14 25 00 b3 5f ff <41> f7 c4 00 02 00 00 74 1a e8 8b 31 17 00 4c 89 e7 57 9d 0f 1f