ptrace attach of "/root/syz-executor.4"[25979] was attempted by "/root/syz-executor.4"[25985]
INFO: rcu_preempt self-detected stall on CPU
	0-...: (10499 ticks this GP) idle=1c6/140000000000002/0 softirq=151697/151697 fqs=5 
	 (t=10500 jiffies g=40177 c=40176 q=238)
NMI backtrace for cpu 0
CPU: 0 PID: 25998 Comm: syz-executor.2 Not tainted 4.14.169-syzkaller #0
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+0x142/0x197 lib/dump_stack.c:58
 nmi_cpu_backtrace.cold+0x57/0x94 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x141/0x189 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:158 [inline]
 rcu_dump_cpu_stacks+0x186/0x1d2 kernel/rcu/tree.c:1396
 print_cpu_stall kernel/rcu/tree.c:1542 [inline]
 check_cpu_stall kernel/rcu/tree.c:1610 [inline]
 __rcu_pending kernel/rcu/tree.c:3390 [inline]
 rcu_pending kernel/rcu/tree.c:3452 [inline]
 rcu_check_callbacks.cold+0x43d/0xd0a kernel/rcu/tree.c:2792
 update_process_times+0x31/0x70 kernel/time/timer.c:1590
 tick_sched_handle+0x85/0x160 kernel/time/tick-sched.c:165
 tick_sched_timer+0x43/0x130 kernel/time/tick-sched.c:1223
 __run_hrtimer kernel/time/hrtimer.c:1223 [inline]
 __hrtimer_run_queues+0x270/0xbc0 kernel/time/hrtimer.c:1287
 hrtimer_interrupt+0x1d8/0x5d0 kernel/time/hrtimer.c:1321
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1075 [inline]
 smp_apic_timer_interrupt+0x11c/0x5e0 arch/x86/kernel/apic/apic.c:1100
 apic_timer_interrupt+0x96/0xa0 arch/x86/entry/entry_64.S:792
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x54/0x90 kernel/locking/spinlock.c:200
RSP: 0018:ffff8880aec07df0 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff10
RAX: 1ffffffff0fe2ce3 RBX: ffff888075311a58 RCX: 1ffff110421f25b3
RDX: dffffc0000000000 RSI: ffff888210f92d78 RDI: ffff888210f92cfc
RBP: ffff8880aec07df8 R08: ffff888210f92480 R09: ffff888210f92d98
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880aec239c0
R13: ffff888075311a40 R14: ffff8880aec239c0 R15: dffffc0000000000
 expire_timers kernel/time/timer.c:1317 [inline]
 __run_timers kernel/time/timer.c:1636 [inline]
 __run_timers kernel/time/timer.c:1604 [inline]
 run_timer_softirq+0x5a5/0x1520 kernel/time/timer.c:1649
 __do_softirq+0x244/0x9a0 kernel/softirq.c:288
 invoke_softirq kernel/softirq.c:368 [inline]
 irq_exit+0x160/0x1b0 kernel/softirq.c:409
 exiting_irq arch/x86/include/asm/apic.h:648 [inline]
 smp_apic_timer_interrupt+0x146/0x5e0 arch/x86/kernel/apic/apic.c:1102
 apic_timer_interrupt+0x96/0xa0 arch/x86/entry/entry_64.S:792
 </IRQ>
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:779 [inline]
RIP: 0010:lock_acquire+0x1ea/0x430 kernel/locking/lockdep.c:3997
RSP: 0018:ffff88820ff67c20 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff10
RAX: 1ffffffff0fe2ce1 RBX: ffff888210f92480 RCX: 000000009c70e0b3
RDX: dffffc0000000000 RSI: ffff888210f92d78 RDI: 0000000000000286
RBP: ffff88820ff67c68 R08: 000000000000106c R09: ffffffff89557be0
R10: ffff888210f92d78 R11: ffff888210f92480 R12: ffff8882199e1bd8
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
 _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:152
 spin_lock include/linux/spinlock.h:317 [inline]
 fast_dput fs/dcache.c:711 [inline]
 dput.part.0+0x3d2/0x750 fs/dcache.c:818
 dput+0x20/0x30 fs/dcache.c:811
 path_put+0x31/0x70 fs/namei.c:501
 chroot_fs_refs+0x2f2/0x530 fs/fs_struct.c:84
 SYSC_pivot_root fs/namespace.c:3236 [inline]
 SyS_pivot_root+0xac3/0xea0 fs/namespace.c:3156
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45b399
RSP: 002b:00007f5c7504bc78 EFLAGS: 00000246 ORIG_RAX: 000000000000009b
RAX: ffffffffffffffda RBX: 00007f5c7504c6d4 RCX: 000000000045b399
RDX: 0000000000000000 RSI: 0000000020000080 RDI: 0000000020000040
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000815 R14: 00000000004c9813 R15: 000000000075bf2c
INFO: rcu_sched detected stalls on CPUs/tasks:
	0-...: (10500 ticks this GP) idle=1c6/140000000000001/0 softirq=151697/151697 fqs=6 
	(detected by 1, t=10536 jiffies, g=34054, c=34053, q=4)