INFO: task syz-executor0:3894 blocked for more than 140 seconds.
      Not tainted 4.4.140-ged9bdc8 #4
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor0   D ffff8801c06279c8 26144  3894      1 0x20020004
 ffff8801c06279c8 0000000000000000 ffff8801d94d38e0 ffffed003b29a71b
 ffff8801d94d3000 ffff8801db21fdb8 ffff8801db21fde0 ffff8801db21f4d8
 ffff8801db21f4c0 ffff8800bb8b4800 ffff8801d94d3000 0000000000000000
Call Trace:
 [<ffffffff838b476a>] schedule+0x7a/0x1b0 kernel/sched/core.c:3359
 [<ffffffff838b4f03>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3392
 [<ffffffff838bb047>] __mutex_lock_common kernel/locking/mutex.c:582 [inline]
 [<ffffffff838bb047>] mutex_lock_nested+0x307/0x850 kernel/locking/mutex.c:621
 [<ffffffff8251b0ab>] lo_ioctl+0x8b/0x1ad0 drivers/block/loop.c:1355
 [<ffffffff8251cba2>] lo_compat_ioctl+0xb2/0x140 drivers/block/loop.c:1551
 [<ffffffff81dffb95>] compat_blkdev_ioctl+0x395/0x3a10 block/compat_ioctl.c:751
 [<ffffffff81628a44>] C_SYSC_ioctl fs/compat_ioctl.c:1592 [inline]
 [<ffffffff81628a44>] compat_SyS_ioctl+0x484/0x2270 fs/compat_ioctl.c:1544
 [<ffffffff81006d96>] do_syscall_32_irqs_on arch/x86/entry/common.c:392 [inline]
 [<ffffffff81006d96>] do_fast_syscall_32+0x326/0x8b0 arch/x86/entry/common.c:459
 [<ffffffff838c40ea>] sysenter_flags_fixed+0xd/0x17
1 lock held by syz-executor0/3894:
 #0:  (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<ffffffff8251b0ab>] lo_ioctl+0x8b/0x1ad0 drivers/block/loop.c:1355
Sending NMI to all CPUs:
NMI backtrace for cpu 0
CPU: 0 PID: 3731 Comm: rsyslogd Not tainted 4.4.140-ged9bdc8 #4
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8800accd6000 task.stack: ffff8801c7a20000
RIP: 0010:[<ffffffff81033eb0>]  [<ffffffff81033eb0>] save_stack_address+0x0/0x30 arch/x86/kernel/stacktrace.c:81
RSP: 0018:ffff8801c7a277c0  EFLAGS: 00000246
RAX: ffff8801c7a27ae0 RBX: ffff8801c7a27ad8 RCX: ffffffff81033eb0
RDX: 0000000000000000 RSI: ffffffff81033e46 RDI: ffff8801c7a278b8
RBP: ffff8801c7a27810 R08: ffff8801c7a278b8 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffffffff8000
R13: ffffffff81033e46 R14: ffff8801c7a278d0 R15: 0000000000000000
FS:  00007f682cb50700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff7eb642140 CR3: 00000001c7d9f000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff810167ed ffff8801c7a27ad8 ffff8801c7a278b8 ffffffff83a10a60
 ffff8801c7a20000 ffff8800accd6000 ffffffff83a10a60 ffff8801c7a278b8
 ffff8801db207fc0 ffff8801c7a27858 ffff8801c7a27890 ffffffff81015d0a
Call Trace:
 [<ffffffff81015d0a>] dump_trace+0x17a/0x360 arch/x86/kernel/dumpstack_64.c:243
 [<ffffffff81033e46>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff814f8913>] save_stack+0x43/0xd0 mm/kasan/kasan.c:512
 [<ffffffff814f8bf7>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff814f8bf7>] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:616
 [<ffffffff814f91c2>] kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:554
 [<ffffffff814f4f63>] slab_post_alloc_hook mm/slub.c:1349 [inline]
 [<ffffffff814f4f63>] slab_alloc_node mm/slub.c:2615 [inline]
 [<ffffffff814f4f63>] slab_alloc mm/slub.c:2623 [inline]
 [<ffffffff814f4f63>] kmem_cache_alloc_trace+0xc3/0x2c0 mm/slub.c:2640
 [<ffffffff8125be43>] kmalloc include/linux/slab.h:476 [inline]
 [<ffffffff8125be43>] syslog_print kernel/printk/printk.c:1148 [inline]
 [<ffffffff8125be43>] do_syslog+0x603/0xb20 kernel/printk/printk.c:1331
 [<ffffffff8169b2d4>] kmsg_read+0x74/0xa0 fs/proc/kmsg.c:39
 [<ffffffff816715e9>] proc_reg_read+0xf9/0x180 fs/proc/inode.c:202
 [<ffffffff8151c87c>] __vfs_read+0x11c/0x3e0 fs/read_write.c:432
 [<ffffffff8151e670>] vfs_read+0x130/0x360 fs/read_write.c:454
 [<ffffffff81520e79>] SYSC_read fs/read_write.c:569 [inline]
 [<ffffffff81520e79>] SyS_read+0xd9/0x1c0 fs/read_write.c:562
 [<ffffffff838c27a5>] entry_SYSCALL_64_fastpath+0x22/0x9e
Code: f3 31 f6 e8 03 1d fe ff 8b 03 3b 43 04 73 11 48 8b 53 08 8d 48 01 89 0b 48 c7 04 c2 ff ff ff ff 5b 5d c3 0f 1f 84 00 00 00 00 00 <85> d2 74 1b 8b 47 10 85 c0 7f 15 8b 07 3b 47 04 73 0d 48 8b 57 
NMI backtrace for cpu 1
CPU: 1 PID: 491 Comm: khungtaskd Not tainted 4.4.140-ged9bdc8 #4
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8800bb326000 task.stack: ffff8800bb1d0000
RIP: 0010:[<ffffffff810bff96>]  [<ffffffff810bff96>] native_apic_mem_write arch/x86/include/asm/apic.h:94 [inline]
RIP: 0010:[<ffffffff810bff96>]  [<ffffffff810bff96>] __default_send_IPI_dest_field arch/x86/include/asm/ipi.h:119 [inline]
RIP: 0010:[<ffffffff810bff96>]  [<ffffffff810bff96>] _flat_send_IPI_mask arch/x86/kernel/apic/apic_flat_64.c:61 [inline]
RIP: 0010:[<ffffffff810bff96>]  [<ffffffff810bff96>] flat_send_IPI_mask+0xf6/0x1a0 arch/x86/kernel/apic/apic_flat_64.c:69
RSP: 0018:ffff8800bb1d7cc8  EFLAGS: 00000046
RAX: 0000000003000000 RBX: 0000000000000c00 RCX: 0000000000000000
RDX: 0000000000000c00 RSI: 0000000000000000 RDI: ffffffffff5fb300
RBP: ffff8800bb1d7cf0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000246
R13: 0000000000000003 R14: 0000000000000002 R15: ffffffff8446f6e0
FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0586ebf000 CR3: 00000001d098d000 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Stack:
 ffffffff8446f6e0 ffffffff84a19060 0000000000000007 fffffbfff0942cbc
 0000000000000040 ffff8800bb1d7d10 ffffffff810b5f51 ffffffff83c0b760
 0000000000000003 ffff8800bb1d7d68 ffffffff81e19103 ffffffff8140ddaf
Call Trace:
 [<ffffffff810b5f51>] nmi_raise_cpu_backtrace+0x61/0x80 arch/x86/kernel/apic/hw_nmi.c:33
 [<ffffffff81e19103>] nmi_trigger_all_cpu_backtrace.cold.4+0x70/0xad lib/nmi_backtrace.c:85
 [<ffffffff810b5ff4>] arch_trigger_all_cpu_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 [<ffffffff8141a499>] trigger_all_cpu_backtrace include/linux/nmi.h:44 [inline]
 [<ffffffff8141a499>] check_hung_task kernel/hung_task.c:125 [inline]
 [<ffffffff8141a499>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline]
 [<ffffffff8141a499>] watchdog.cold.1+0xd3/0xee kernel/hung_task.c:238
 [<ffffffff81190998>] kthread+0x268/0x300 kernel/kthread.c:211
 [<ffffffff838c2bd5>] 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 d2