R13: 00007f2c0f665bc8 R14: 00000000004b75fb R15: 0000000000000000
INFO: rcu_sched self-detected stall on CPU
INFO: rcu_sched detected stalls on CPUs/tasks:
	1-....: (125000 ticks this GP) idle=73a/1/4611686018427387906 softirq=7120/7120 fqs=31155 
	(detected by 0, t=125002 jiffies, g=2566, c=2565, q=615)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4376 Comm: syz-executor7 Not tainted 4.15.0-rc3-next-20171214+ #67
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:inb arch/x86/include/asm/io.h:348 [inline]
RIP: 0010:io_serial_in+0x24/0x30 drivers/tty/serial/8250/8250_port.c:434
RSP: 0018:ffff88021fd03b78 EFLAGS: 00000002
RAX: ffff8801e051c500 RBX: 0000000000000005 RCX: 0000000000000000
RDX: 00000000000003fd RSI: 0000000000000005 RDI: ffffffff83fde540
RBP: ffff88021fd03b88 R08: 0000000000000001 R09: 000000000000000c
R10: ffff88021fd03b80 R11: 000000000000000c R12: ffffffff83fde540
R13: 0000000000000020 R14: ffffffff818a4790 R15: ffffffff83f6b75a
FS:  00007f5784bee700(0000) GS:ffff88021fd00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b9bc23000 CR3: 00000001e312e006 CR4: 00000000001606e0
DR0: 0000000020000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 serial_in drivers/tty/serial/8250/8250.h:111 [inline]
 wait_for_xmitr+0x50/0xd0 drivers/tty/serial/8250/8250_port.c:2033
 serial8250_console_putchar+0x1f/0x30 drivers/tty/serial/8250/8250_port.c:3170
 uart_console_write+0x5f/0x80 drivers/tty/serial/serial_core.c:1858
 serial8250_console_write+0x22e/0x350 drivers/tty/serial/8250/8250_port.c:3236
 univ8250_console_write+0x35/0x40 drivers/tty/serial/8250/8250_core.c:590
 call_console_drivers kernel/printk/printk.c:1574 [inline]
 console_unlock+0x505/0x790 kernel/printk/printk.c:2233
 vprintk_emit+0x38c/0x430 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+0x4f/0x5a kernel/printk/printk.c:1829
 print_cpu_stall_info_begin kernel/rcu/tree_plugin.h:1685 [inline]
 print_cpu_stall kernel/rcu/tree.c:1510 [inline]
 check_cpu_stall kernel/rcu/tree.c:1592 [inline]
 __rcu_pending kernel/rcu/tree.c:3362 [inline]
 rcu_pending kernel/rcu/tree.c:3424 [inline]
 rcu_check_callbacks+0x506/0xa10 kernel/rcu/tree.c:2764
 update_process_times+0x30/0x60 kernel/time/timer.c:1630
 tick_sched_handle+0x32/0x80 kernel/time/tick-sched.c:162
 tick_sched_timer+0x3e/0xa0 kernel/time/tick-sched.c:1148
 __run_hrtimer kernel/time/hrtimer.c:1210 [inline]
 __hrtimer_run_queues+0x10a/0x5e0 kernel/time/hrtimer.c:1274
 hrtimer_interrupt+0xcd/0x260 kernel/time/hrtimer.c:1308
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline]
 smp_apic_timer_interrupt+0x6d/0x2a0 arch/x86/kernel/apic/apic.c:1050
 apic_timer_interrupt+0xa9/0xb0 arch/x86/entry/entry_64.S:920
 </IRQ>
RIP: 0010:__read_once_size include/linux/compiler.h:183 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x3b/0x50 kernel/kcov.c:106
RSP: 0018:ffffc9000110fd98 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff11
RAX: 0000000000010000 RBX: ffffc9000113a060 RCX: ffffffff81878d10
RDX: 000000000000ffff RSI: ffffc900019d9000 RDI: 0000000000000286
RBP: ffffc9000110fd98 R08: 0000000000000001 R09: 0000000000000004
R10: ffffc9000110fd18 R11: 0000000000000004 R12: 000000043de3d858
R13: 0000000020fe7ffc R14: ffffc90001139000 R15: ffff8801e3fa8a38
 inq_canon drivers/tty/n_tty.c:2412 [inline]
 n_tty_ioctl+0x160/0x180 drivers/tty/n_tty.c:2429
 tty_ioctl+0x83e/0xb90 drivers/tty/tty_io.c:2638
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0xaf/0x840 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: 0033:0x452a39
RSP: 002b:00007f5784bedc58 EFLAGS: 00000212 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f5784bed9a0 RCX: 0000000000452a39
RDX: 0000000020fe7ffc RSI: 000000000000541b RDI: 0000000000000014
RBP: 00007f5784bed990 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000004b7246
R13: 00007f5784bedac8 R14: 00000000004b724f R15: 0000000000000000
Code: 5d c3 0f 1f 44 00 00 55 48 89 e5 41 54 53 49 89 fc 89 f3 e8 bf 66 a1 ff 41 0f b6 8c 24 d1 00 00 00 41 8b 54 24 38 d3 e3 01 da ec <5b> 0f b6 c0 41 5c 5d c3 0f 1f 40 00 55 48 89 e5 41 55 41 54 53 
	1-....: (125000 ticks this GP) idle=73a/1/4611686018427387906 softirq=7120/7120 fqs=31255 
	 (t=125409 jiffies g=2566 c=2565 q=615)
NMI backtrace for cpu 1
CPU: 1 PID: 4376 Comm: syz-executor7 Not tainted 4.15.0-rc3-next-20171214+ #67
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+0xe9/0x14b lib/dump_stack.c:53
 nmi_cpu_backtrace+0x149/0x150 lib/nmi_backtrace.c:103
 nmi_trigger_cpumask_backtrace+0x101/0x150 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+0xa7/0xe8 kernel/rcu/tree.c:1375
 print_cpu_stall kernel/rcu/tree.c:1524 [inline]
 check_cpu_stall kernel/rcu/tree.c:1592 [inline]
 __rcu_pending kernel/rcu/tree.c:3362 [inline]
 rcu_pending kernel/rcu/tree.c:3424 [inline]
 rcu_check_callbacks+0x7d9/0xa10 kernel/rcu/tree.c:2764
 update_process_times+0x30/0x60 kernel/time/timer.c:1630
 tick_sched_handle+0x32/0x80 kernel/time/tick-sched.c:162
 tick_sched_timer+0x3e/0xa0 kernel/time/tick-sched.c:1148
 __run_hrtimer kernel/time/hrtimer.c:1210 [inline]
 __hrtimer_run_queues+0x10a/0x5e0 kernel/time/hrtimer.c:1274
 hrtimer_interrupt+0xcd/0x260 kernel/time/hrtimer.c:1308
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline]
 smp_apic_timer_interrupt+0x6d/0x2a0 arch/x86/kernel/apic/apic.c:1050
 apic_timer_interrupt+0xa9/0xb0 arch/x86/entry/entry_64.S:920
 </IRQ>
RIP: 0010:__read_once_size include/linux/compiler.h:183 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x3b/0x50 kernel/kcov.c:106
RSP: 0018:ffffc9000110fd98 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff11
RAX: 0000000000010000 RBX: ffffc9000113a060 RCX: ffffffff81878d10
RDX: 000000000000ffff RSI: ffffc900019d9000 RDI: 0000000000000286
RBP: ffffc9000110fd98 R08: 0000000000000001 R09: 0000000000000004
R10: ffffc9000110fd18 R11: 0000000000000004 R12: 000000043de3d858
R13: 0000000020fe7ffc R14: ffffc90001139000 R15: ffff8801e3fa8a38
 inq_canon drivers/tty/n_tty.c:2412 [inline]
 n_tty_ioctl+0x160/0x180 drivers/tty/n_tty.c:2429
 tty_ioctl+0x83e/0xb90 drivers/tty/tty_io.c:2638
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0xaf/0x840 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: 0033:0x452a39
RSP: 002b:00007f5784bedc58 EFLAGS: 00000212 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f5784bed9a0 RCX: 0000000000452a39
RDX: 0000000020fe7ffc RSI: 000000000000541b RDI: 0000000000000014
RBP: 00007f5784bed990 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000004b7246
R13: 00007f5784bedac8 R14: 00000000004b724f R15: 0000000000000000