INFO: task syz-executor824:3885 blocked for more than 120 seconds.
      Not tainted 4.9.111-g03c70fe #57
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor824 D28504  3885   3882 0x00000000
 ffff8801baff1800 0000000000000000 ffff8801bd3b4000 ffff8801d9a6b000
 ffff8801db321c18 ffff8801d83f79f0 ffffffff839e7ded 0000000000000002
 0000000041b58ab3 ffffffff843bac1b 00ffffff81221510 ffff8801db3224e8
Call Trace:
 [<ffffffff839e93ef>] schedule+0x7f/0x1b0 kernel/sched/core.c:3557
 [<ffffffff81e3fe24>] blk_mq_freeze_queue_wait+0x114/0x230 block/blk-mq.c:75
 [<ffffffff81e4911d>] blk_freeze_queue block/blk-mq.c:92 [inline]
 [<ffffffff81e4911d>] blk_mq_freeze_queue+0x1d/0x20 block/blk-mq.c:101
 [<ffffffff825c98c2>] loop_switch drivers/block/loop.c:599 [inline]
 [<ffffffff825c98c2>] loop_change_fd drivers/block/loop.c:685 [inline]
 [<ffffffff825c98c2>] lo_ioctl+0x722/0x1aa0 drivers/block/loop.c:1350
 [<ffffffff81e56326>] __blkdev_driver_ioctl block/ioctl.c:294 [inline]
 [<ffffffff81e56326>] blkdev_ioctl+0x7b6/0x1a70 block/ioctl.c:590
 [<ffffffff81632c5e>] block_ioctl+0xde/0x120 fs/block_dev.c:1688
 [<ffffffff815b2c6c>] vfs_ioctl fs/ioctl.c:43 [inline]
 [<ffffffff815b2c6c>] file_ioctl fs/ioctl.c:493 [inline]
 [<ffffffff815b2c6c>] do_vfs_ioctl+0x1ac/0x11a0 fs/ioctl.c:677
 [<ffffffff815b3cef>] SYSC_ioctl fs/ioctl.c:694 [inline]
 [<ffffffff815b3cef>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f8cd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Showing all locks held in the system:
2 locks held by khungtaskd/519:
 #0:  (rcu_read_lock){......}, at: [<ffffffff813666fc>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline]
 #0:  (rcu_read_lock){......}, at: [<ffffffff813666fc>] watchdog+0x11c/0xa20 kernel/hung_task.c:239
 #1:  (tasklist_lock){.+.+..}, at: [<ffffffff81425d87>] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336
2 locks held by getty/3777:
 #0:  (&tty->ldisc_sem){++++++}, at: [<ffffffff839f6e92>] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367
 #1:  (&ldata->atomic_read_lock){+.+...}, at: [<ffffffff8211e602>] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2133
1 lock held by syz-executor824/3885:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c922b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor824/3887:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c922b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor824/3888:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c922b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor824/3890:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c922b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor824/3891:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c922b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor824/3892:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c922b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor824/3893:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c922b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor824/3894:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c922b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor824/3895:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c922b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor824/3896:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c922b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor824/3897:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c922b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor824/3898:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c922b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor824/3899:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c922b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor824/3900:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c922b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor824/3901:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c922b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344
1 lock held by syz-executor824/3902:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff825c922b>] lo_ioctl+0x8b/0x1aa0 drivers/block/loop.c:1344

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

NMI backtrace for cpu 0
CPU: 0 PID: 519 Comm: khungtaskd Not tainted 4.9.111-g03c70fe #57
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801d8557d08 ffffffff81eb2729 0000000000000000 0000000000000000
 0000000000000000 0000000000000001 ffffffff810b9af0 ffff8801d8557d40
 ffffffff81ebda27 0000000000000000 0000000000000000 0000000000000003
Call Trace:
 [<ffffffff81eb2729>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb2729>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81ebda27>] nmi_cpu_backtrace.cold.2+0x48/0x87 lib/nmi_backtrace.c:99
 [<ffffffff81ebd9ba>] nmi_trigger_cpumask_backtrace+0x12a/0x14f lib/nmi_backtrace.c:60
 [<ffffffff810b9bf4>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37
 [<ffffffff81366c94>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline]
 [<ffffffff81366c94>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff81366c94>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff81366c94>] watchdog+0x6b4/0xa20 kernel/hung_task.c:239
 [<ffffffff8119d05d>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff839f8e9c>] 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
CPU: 1 PID: 3884 Comm: syz-executor824 Not tainted 4.9.111-g03c70fe #57
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d8bd6000 task.stack: ffff8801d8228000
RIP: 0010:[<ffffffff8153a922>] 
c [<ffffffff8153a922>] kasan_mem_to_shadow include/linux/kasan.h:29 [inline]
RIP: 0010:[<ffffffff8153a922>] 
c [<ffffffff8153a922>] memory_is_poisoned_n mm/kasan/kasan.c:266 [inline]
RIP: 0010:[<ffffffff8153a922>] 
c [<ffffffff8153a922>] memory_is_poisoned mm/kasan/kasan.c:299 [inline]
RIP: 0010:[<ffffffff8153a922>] 
c [<ffffffff8153a922>] check_memory_region_inline mm/kasan/kasan.c:315 [inline]
RIP: 0010:[<ffffffff8153a922>] 
c [<ffffffff8153a922>] check_memory_region+0x52/0x1b0 mm/kasan/kasan.c:325
RSP: 0018:ffff8801d822fb58  EFLAGS: 00000286
RAX: ffffed0036ffd0c3 RBX: 1ffff10036ffd0c3 RCX: ffffffff81efe2b4
RDX: 0000000000000001 RSI: 0000000000000012 RDI: ffff8801b7fe861e
RBP: ffff8801d822fb70 R08: ffff8801d8bd6910 R09: ffffed0036ffd0c3
R10: ffffed0036ffd0c5 R11: ffff8801b7fe862f R12: ffffed0036ffd0c6
R13: 0000000000000012 R14: ffff8801d822fcd0 R15: ffff8801b7fe861e
FS:  0000000001597880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f17fc76c000 CR3: 00000001b8814000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffff8801d822fd70
c ffff880000000000
c 0000000000000012
c ffff8801d822fb80
c
 ffffffff8153aab4
c ffff8801d822fbf0
c ffffffff81efe2b4
c 00000000004addfd
c
 ffff8801d822fd78
c ffff8801d822fd88
c ffff8801d822fcd8
c ffff8801d822fd80
c
Call Trace:
 [<ffffffff8153aab4>] kasan_check_write+0x14/0x20 mm/kasan/kasan.c:336
 [<ffffffff81efe2b4>] __copy_from_user arch/x86/include/asm/uaccess_64.h:114 [inline]
 [<ffffffff81efe2b4>] copy_page_from_iter_iovec lib/iov_iter.c:267 [inline]
 [<ffffffff81efe2b4>] copy_page_from_iter+0x1a4/0x610 lib/iov_iter.c:618
 [<ffffffff8158d642>] pipe_write+0x722/0xd60 fs/pipe.c:391
 [<ffffffff8156ec30>] new_sync_write fs/read_write.c:496 [inline]
 [<ffffffff8156ec30>] __vfs_write+0x3e0/0x580 fs/read_write.c:509
 [<ffffffff81572a27>] vfs_write+0x187/0x530 fs/read_write.c:557
 [<ffffffff81576859>] SYSC_write fs/read_write.c:604 [inline]
 [<ffffffff81576859>] SyS_write+0xd9/0x1c0 fs/read_write.c:596
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff839f8cd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Code: 
c00 
c4c 
c8d 
c5c 
c37 
cff 
c48 
c89 
cfb 
c49 
cb9 
c00 
c00 
c00 
c00 
c00 
cfc 
cff 
cdf 
c4d 
c89 
cda 
c48 
cc1 
ceb 
c03 
c49 
cc1 
cea 
c03 
c4d 
c01 
cca 
c49 
c01 
cd9 
c4d 
c8d 
c62 
c01 
c4c 
c89 
cc8 
c<4d> 
c89 
ce0 
c4d 
c29 
cc8 
c49 
c83 
cf8 
c10 
c0f 
c8e 
c9c 
c00 
c00 
c00 
c44 
c89 
ccb 
c83 
ce3 
c