syzbot

INFO: task syz-executor2:8717 blocked for more than 120 seconds.
      Not tainted 4.4.112-g3fc4284 #32
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor2   D ffff8800b44efa78 29248  8717   5067 0x00000004
 ffff8800b44efa78 ffff8800b44efa28 0000000000000246 0000000000000296
 0000000041b58ab3 ffffffff83fa8900 ffff8801db21fdb8 ffff8801db21fde0
 ffff8801db21f4d8 ffff8801d315c740 ffff8801c53edf00 ffff8800b44e8000
Call Trace:
 [<ffffffff8376810a>] schedule+0x9a/0x1c0 kernel/sched/core.c:3351
 [<ffffffff81c97810>] blk_mq_freeze_queue_wait+0x120/0x240 block/blk-mq.c:95
 [<ffffffff81c9fd8d>] blk_freeze_queue block/blk-mq.c:112 [inline]
 [<ffffffff81c9fd8d>] blk_mq_freeze_queue+0x1d/0x20 block/blk-mq.c:121
 [<ffffffff82421b7f>] loop_switch drivers/block/loop.c:610 [inline]
 [<ffffffff82421b7f>] loop_change_fd drivers/block/loop.c:693 [inline]
 [<ffffffff82421b7f>] lo_ioctl+0xfef/0x19c0 drivers/block/loop.c:1354
 [<ffffffff81cad98b>] __blkdev_driver_ioctl block/ioctl.c:288 [inline]
 [<ffffffff81cad98b>] blkdev_ioctl+0x4ab/0x1990 block/ioctl.c:584
 [<ffffffff815d1c1e>] block_ioctl+0xde/0x120 fs/block_dev.c:1625
 [<ffffffff815599ca>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff815599ca>] do_vfs_ioctl+0x7aa/0xee0 fs/ioctl.c:607
 [<ffffffff8155a18f>] SYSC_ioctl fs/ioctl.c:622 [inline]
 [<ffffffff8155a18f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:613
 [<ffffffff837761d9>] entry_SYSCALL_64_fastpath+0x16/0x92
1 lock held by syz-executor2/8717:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff82420c1f>] lo_ioctl+0x8f/0x19c0 drivers/block/loop.c:1348
Sending NMI to all CPUs:
NMI backtrace for cpu 0
CPU: 0 PID: 486 Comm: khungtaskd Not tainted 4.4.112-g3fc4284 #32
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8800bacd2f80 task.stack: ffff8800bb148000
RIP: 0010:[<ffffffff810c3e87>]  [<ffffffff810c3e87>] native_apic_mem_write arch/x86/include/asm/apic.h:94 [inline]
RIP: 0010:[<ffffffff810c3e87>]  [<ffffffff810c3e87>] __default_send_IPI_dest_field arch/x86/include/asm/ipi.h:119 [inline]
RIP: 0010:[<ffffffff810c3e87>]  [<ffffffff810c3e87>] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:61 [inline]
RIP: 0010:[<ffffffff810c3e87>]  [<ffffffff810c3e87>] flat_send_IPI_mask+0xf7/0x1a0 arch/x86/kernel/apic/apic_flat_64.c:69
RSP: 0018:ffff8800bb14fcb8  EFLAGS: 00000046
RAX: 0000000003000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fb300
RBP: ffff8800bb14fce0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000246
R13: 0000000000000003 R14: ffffffff8426ec20 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7811f43000 CR3: 00000000b5f64000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff8426ec20 ffffffff847ee640 000000000001bca0 0000000000000040
 dffffc0000000000 ffff8800bb14fd00 ffffffff810b99bb ffffffff839f5940
 0000000000000003 ffff8800bb14fd60 ffffffff81d10447 ffffffff8141a2f3
Call Trace:
 [<ffffffff810b99bb>] nmi_raise_cpu_backtrace+0x5b/0x70 arch/x86/kernel/apic/hw_nmi.c:33
 [<ffffffff81d10447>] nmi_trigger_all_cpu_backtrace+0x4a7/0x550 lib/nmi_backtrace.c:85
 [<ffffffff810b9a54>] arch_trigger_all_cpu_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 [<ffffffff81367d9a>] trigger_all_cpu_backtrace include/linux/nmi.h:44 [inline]
 [<ffffffff81367d9a>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81367d9a>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81367d9a>] watchdog+0x6fa/0xae0 kernel/hung_task.c:238
 [<ffffffff81190958>] kthread+0x268/0x300 kernel/kthread.c:211
 [<ffffffff837765df>] ret_from_fork+0x3f/0x70 arch/x86/entry/entry_64.S:494
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 3b 1f 17 00 4c 89 e7 57 9d 0f 1f 
NMI backtrace for cpu 1
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.4.112-g3fc4284 #32
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801da3a97c0 task.stack: ffff8801da3b8000
RIP: 0010:[<ffffffff810d0526>]  [<ffffffff810d0526>] native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:49
RSP: 0018:ffff8801da3bfd78  EFLAGS: 00000246
RAX: 0000000000000007 RBX: ffffffff847dc748 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff8801da3aa02c
RBP: ffff8801da3bfd78 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001
R13: 0000000000000000 R14: 0000000000000000 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe64b403e8 CR3: 00000000b5f64000 CR4: 0000000000160670
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801da3bfdb0 ffffffff81027ee5 ffff8801da3c0000 ffffffff847dc748
 0000000000000000 0000000000000000 dffffc0000000000 ffff8801da3bfdc0
 ffffffff8102945a ffff8801da3bfdd8 ffffffff812204d8 ffff8801da3c0000
Call Trace:
 [<ffffffff81027ee5>] arch_safe_halt arch/x86/include/asm/paravirt.h:117 [inline]
 [<ffffffff81027ee5>] default_idle+0x55/0x3c0 arch/x86/kernel/process.c:291
 [<ffffffff8102945a>] arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:282
 [<ffffffff812204d8>] default_idle_call+0x48/0x70 kernel/sched/idle.c:93
 [<ffffffff81220be5>] cpuidle_idle_call kernel/sched/idle.c:157 [inline]
 [<ffffffff81220be5>] cpu_idle_loop kernel/sched/idle.c:253 [inline]
 [<ffffffff81220be5>] cpu_startup_entry+0x605/0x820 kernel/sched/idle.c:301
 [<ffffffff810adc64>] start_secondary+0x304/0x3e0 arch/x86/kernel/smpboot.c:242
Code: 00 00 00 00 00 55 48 89 e5 fa 5d c3 66 0f 1f 84 00 00 00 00 00 55 48 89 e5 fb 5d c3 66 0f 1f 84 00 00 00 00 00 55 48 89 e5 fb f4 <5d> c3 0f 1f 84 00 00 00 00 00 55 48 89 e5 f4 5d c3 66 0f 1f 84