INFO: rcu_sched self-detected stall on CPU
	0-....: (124998 ticks this GP) idle=576/1/4611686018427387906 softirq=29499/29499 fqs=31213 
	 (t=125000 jiffies g=16558 c=16557 q=497)
NMI backtrace for cpu 0
CPU: 0 PID: 9925 Comm: syz-executor0 Not tainted 4.15.0-rc1-mm1+ #29
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:53
 nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103
 nmi_trigger_cpumask_backtrace+0x122/0x180 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_single_cpu_backtrace include/linux/nmi.h:156 [inline]
 rcu_dump_cpu_stacks+0x186/0x1da kernel/rcu/tree.c:1375
 print_cpu_stall kernel/rcu/tree.c:1524 [inline]
 check_cpu_stall.isra.64+0xbb8/0x15b0 kernel/rcu/tree.c:1592
 __rcu_pending kernel/rcu/tree.c:3361 [inline]
 rcu_pending kernel/rcu/tree.c:3423 [inline]
 rcu_check_callbacks+0x238/0xd20 kernel/rcu/tree.c:2763
 update_process_times+0x30/0x60 kernel/time/timer.c:1640
 tick_sched_handle+0x85/0x160 kernel/time/tick-sched.c:162
 tick_sched_timer+0x42/0x120 kernel/time/tick-sched.c:1166
 __run_hrtimer kernel/time/hrtimer.c:1348 [inline]
 __hrtimer_run_queues+0x373/0xea0 kernel/time/hrtimer.c:1411
 hrtimer_interrupt+0x2a5/0x6f0 kernel/time/hrtimer.c:1469
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline]
 smp_apic_timer_interrupt+0x14a/0x700 arch/x86/kernel/apic/apic.c:1050
 apic_timer_interrupt+0xa9/0xb0 arch/x86/entry/entry_64.S:907
 </IRQ>
RIP: 0010:__write_once_size include/linux/compiler.h:212 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x4b/0x50 kernel/kcov.c:109
RSP: 0018:ffff8801d5f57a90 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff11
RAX: 0000000000010000 RBX: dffffc0000000000 RCX: ffffffff838b9f77
RDX: 0000000000010000 RSI: ffffc900017c6000 RDI: ffff8801c434d9d8
RBP: ffff8801d5f57a90 R08: ffffffff85f44cc0 R09: 1ffff1003abeaefd
R10: ffff8801d1bae240 R11: 0000000000000001 R12: ffff8801cfb08a38
R13: ffff8801d4dd2000 R14: ffff8801d6a09080 R15: ffff8801d4dd2158
 is_loop_device drivers/block/loop.c:691 [inline]
 loop_set_fd drivers/block/loop.c:879 [inline]
 lo_ioctl+0x567/0x1b90 drivers/block/loop.c:1358
 __blkdev_driver_ioctl block/ioctl.c:303 [inline]
 blkdev_ioctl+0x1759/0x1e00 block/ioctl.c:601
 block_ioctl+0xea/0x130 fs/block_dev.c:1860
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:686
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
 entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x4529d9
RSP: 002b:00007f04c7e33c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000758020 RCX: 00000000004529d9
RDX: 0000000000000016 RSI: 0000000000004c00 RDI: 0000000000000015
RBP: 000000000000005b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006ed928
R13: 00000000ffffffff R14: 00007f04c7e346d4 R15: 0000000000000000