INFO: rcu_sched self-detected stall on CPU
INFO: rcu_sched detected stalls on CPUs/tasks:
	0-....: (125000 ticks this GP) idle=83e/140000000000001/0 softirq=8917/8918 fqs=31236 
	(detected by 1, t=125002 jiffies, g=4477, c=4476, q=195)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 3934 Comm: syz-executor2 Not tainted 4.15.0-rc4+ #232
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:rep_nop arch/x86/include/asm/processor.h:651 [inline]
RIP: 0010:delay_tsc+0x41/0x70 arch/x86/lib/delay.c:67
RSP: 0018:ffff8801db406ff0 EFLAGS: 00000003
RAX: 0000005686ec5ac2 RBX: ffffffff87deaf00 RCX: 0000005686ec5736
RDX: 000000000000038c RSI: 0000000000000000 RDI: 00000000000008fd
RBP: ffff8801db406ff0 R08: 1ffff1003b680d57 R09: 000000000000000c
R10: ffff8801db406f78 R11: 0000000000000040 R12: 0000000000002709
R13: 0000000000000020 R14: fffffbfff0fbd625 R15: fffffbfff0fbd5e9
FS:  00007f041f542700(0000) GS:ffff8801db400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000006efa88 CR3: 00000001bc551002 CR4: 00000000001606f0
DR0: 0000000020001000 DR1: 0000000020000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 __delay arch/x86/lib/delay.c:161 [inline]
 __const_udelay+0x5b/0x70 arch/x86/lib/delay.c:175
 wait_for_xmitr+0x6f/0x1e0 drivers/tty/serial/8250/8250_port.c:2041
 serial8250_console_putchar+0x1f/0x60 drivers/tty/serial/8250/8250_port.c:3170
 uart_console_write+0xac/0xe0 drivers/tty/serial/serial_core.c:1858
 serial8250_console_write+0x64f/0xa40 drivers/tty/serial/8250/8250_port.c:3236
 univ8250_console_write+0x5f/0x70 drivers/tty/serial/8250/8250_core.c:590
 call_console_drivers kernel/printk/printk.c:1574 [inline]
 console_unlock+0x788/0xd80 kernel/printk/printk.c:2233
 vprintk_emit+0x4ad/0x590 kernel/printk/printk.c:1757
 vprintk_default+0x28/0x30 kernel/printk/printk.c:1796
 vprintk_func+0x57/0xc0 kernel/printk/printk_safe.c:379
 printk+0xaa/0xca kernel/printk/printk.c:1829
 print_cpu_stall_info_begin kernel/rcu/tree_plugin.h:1657 [inline]
 print_cpu_stall kernel/rcu/tree.c:1594 [inline]
 check_cpu_stall.isra.61+0x845/0x15b0 kernel/rcu/tree.c:1676
 __rcu_pending kernel/rcu/tree.c:3440 [inline]
 rcu_pending kernel/rcu/tree.c:3502 [inline]
 rcu_check_callbacks+0x256/0xd00 kernel/rcu/tree.c:2842
 update_process_times+0x30/0x60 kernel/time/timer.c:1630
 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:1211 [inline]
 __hrtimer_run_queues+0x358/0xe20 kernel/time/hrtimer.c:1275
 hrtimer_interrupt+0x1c2/0x5e0 kernel/time/hrtimer.c:1309
 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:904
 </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:ffff8801bc6f7b38 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff11
RAX: 0000000000010000 RBX: ffffc90001257060 RCX: ffffffff82870776
RDX: 0000000000010000 RSI: ffffc90002333000 RDI: ffffc90001258260
RBP: ffff8801bc6f7b38 R08: 1ffff100378dee99 R09: 0000000000000004
R10: ffff8801bc6f7988 R11: 0000000000000003 R12: ffffc90001256000
R13: 00000004a1996102 R14: 0000000020e2cffc R15: ffff8801bc76c6f8
 inq_canon drivers/tty/n_tty.c:2412 [inline]
 n_tty_ioctl+0x266/0x2d0 drivers/tty/n_tty.c:2429
 tty_ioctl+0x336/0x1610 drivers/tty/tty_io.c:2638
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0x1b1/0x1520 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: 0033:0x452a09
RSP: 002b:00007f041f541c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452a09
RDX: 0000000020e2cffc RSI: 000000000000541b RDI: 0000000000000014
RBP: 00000000000005c0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f5aa0
R13: 00000000ffffffff R14: 00007f041f5426d4 R15: 0000000000000000
Code: 31 48 c1 e2 20 48 89 d1 48 09 c1 0f ae e8 0f 31 48 c1 e2 20 48 09 d0 48 89 c2 48 29 ca 48 39 fa 73 25 65 ff 0d 01 e1 eb 7a f3 90 <65> ff 05 f8 e0 eb 7a 65 8b 15 d1 ad eb 7a 39 f2 74 ce 48 29 c1 
	0-....: (125000 ticks this GP) idle=83e/140000000000001/0 softirq=8917/8918 fqs=31401 
	 (t=125670 jiffies g=4477 c=4476 q=195)
NMI backtrace for cpu 0
CPU: 0 PID: 3934 Comm: syz-executor2 Not tainted 4.15.0-rc4+ #232
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+0x186/0x1d9 kernel/rcu/tree.c:1459
 print_cpu_stall kernel/rcu/tree.c:1608 [inline]
 check_cpu_stall.isra.61+0xbb8/0x15b0 kernel/rcu/tree.c:1676
 __rcu_pending kernel/rcu/tree.c:3440 [inline]
 rcu_pending kernel/rcu/tree.c:3502 [inline]
 rcu_check_callbacks+0x256/0xd00 kernel/rcu/tree.c:2842
 update_process_times+0x30/0x60 kernel/time/timer.c:1630
 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:1211 [inline]
 __hrtimer_run_queues+0x358/0xe20 kernel/time/hrtimer.c:1275
 hrtimer_interrupt+0x1c2/0x5e0 kernel/time/hrtimer.c:1309
 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:904
 </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:ffff8801bc6f7b38 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff11
RAX: 0000000000010000 RBX: ffffc90001257060 RCX: ffffffff82870776
RDX: 0000000000010000 RSI: ffffc90002333000 RDI: ffffc90001258260
RBP: ffff8801bc6f7b38 R08: 1ffff100378dee99 R09: 0000000000000004
R10: ffff8801bc6f7988 R11: 0000000000000003 R12: ffffc90001256000
R13: 00000004a1996102 R14: 0000000020e2cffc R15: ffff8801bc76c6f8
 inq_canon drivers/tty/n_tty.c:2412 [inline]
 n_tty_ioctl+0x266/0x2d0 drivers/tty/n_tty.c:2429
 tty_ioctl+0x336/0x1610 drivers/tty/tty_io.c:2638
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0x1b1/0x1520 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: 0033:0x452a09
RSP: 002b:00007f041f541c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452a09
RDX: 0000000020e2cffc RSI: 000000000000541b RDI: 0000000000000014
RBP: 00000000000005c0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f5aa0
R13: 00000000ffffffff R14: 00007f041f5426d4 R15: 0000000000000000