syzbot

INFO: rcu_sched self-detected stall on CPU
	0-....: (1 GPs behind) idle=652/1/4611686018427387906 softirq=138099/138226 fqs=29961 
	 (t=120000 jiffies g=74589 c=74588 q=2536)
NMI backtrace for cpu 0
CPU: 0 PID: 22813 Comm: syz-executor1 Not tainted 4.17.0+ #9
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x185/0x1d0 lib/dump_stack.c:113
 nmi_cpu_backtrace lib/nmi_backtrace.c:103 [inline]
 nmi_trigger_cpumask_backtrace+0x262/0x4c0 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x2c/0x40 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_single_cpu_backtrace include/linux/nmi.h:156 [inline]
 rcu_dump_cpu_stacks+0x307/0x4b0 kernel/rcu/tree.c:1376
 print_cpu_stall kernel/rcu/tree.c:1525 [inline]
 check_cpu_stall kernel/rcu/tree.c:1593 [inline]
 __rcu_pending kernel/rcu/tree.c:3356 [inline]
 rcu_pending kernel/rcu/tree.c:3401 [inline]
 rcu_check_callbacks+0x11c5/0x2ae0 kernel/rcu/tree.c:2763
 update_process_times+0x132/0x1a0 kernel/time/timer.c:1636
 tick_sched_handle kernel/time/tick-sched.c:164 [inline]
 tick_sched_timer+0x3ba/0x520 kernel/time/tick-sched.c:1274
 __run_hrtimer kernel/time/hrtimer.c:1398 [inline]
 __hrtimer_run_queues+0xc54/0x1630 kernel/time/hrtimer.c:1460
 hrtimer_interrupt+0x451/0x13c0 kernel/time/hrtimer.c:1518
 local_apic_timer_interrupt+0x6b/0x250 arch/x86/kernel/apic/apic.c:1025
 smp_apic_timer_interrupt+0x5a/0x90 arch/x86/kernel/apic/apic.c:1053
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:866
 </IRQ>
RIP: 0010:msan_get_shadow_origin_ptr+0x8/0x230 mm/kmsan/kmsan_instr.c:229
RSP: 0018:ffff8801b309f840 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 00000000000003d0 RBX: ffff8801d37403d0 RCX: ffff880000000000
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff8801db42a440
RBP: ffff8801b309f850 R08: 0000000001080020 R09: 0000000000000002
R10: 0000000000000000 R11: ffffffff861c6920 R12: ffff8801bfb26098
R13: 0000000000700000 R14: 0000000000000000 R15: ffff8801db42a440
 __msan_metadata_ptr_for_load_8+0x10/0x20 mm/kmsan/kmsan_instr.c:321
 loop_set_fd drivers/block/loop.c:907 [inline]
 lo_ioctl+0x105f/0x4450 drivers/block/loop.c:1398
 __blkdev_driver_ioctl block/ioctl.c:303 [inline]
 blkdev_ioctl+0x2290/0x4f80 block/ioctl.c:601
 block_ioctl+0x16f/0x1d0 fs/block_dev.c:1877
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0xcbd/0x24b0 fs/ioctl.c:686
 ksys_ioctl fs/ioctl.c:701 [inline]
 __do_sys_ioctl fs/ioctl.c:708 [inline]
 __se_sys_ioctl fs/ioctl.c:706 [inline]
 __x64_sys_ioctl+0x280/0x320 fs/ioctl.c:706
 do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x455a99
RSP: 002b:00007f1465da7c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f1465da86d4 RCX: 0000000000455a99
RDX: 0000000000000014 RSI: 0000000000004c00 RDI: 0000000000000015
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004be07c R14: 00000000004cc498 R15: 0000000000000000