Hello,

FYI this happens in mainline kernel 4.14.0-02748-gabc36be.
It shows up since v4.13 .

It occurs in 1 out of 2 boots.

[   26.681423] /usr/bin/curl -sSf http://inn:80/~lkp/cgi-bin/lkp-jobfile-append-var?job_file=/lkp/scheduled/vm-ivb41-1G-7/boot-1-debian-x86_64-2016-08-31.cgz-abc36be236358162202e86ad88616ff95a755101-20171115-43155-csfyyy-0.yaml&job_state=running -o /dev/null
[   26.681431]
[   27.694708] random: crng init done
[   30.041574] irq 3: nobody cared (try booting with the "irqpoll" option)
[   30.042645] CPU: 0 PID: 4421 Comm: dmesg Not tainted 4.14.0-02748-gabc36be #2
[   30.043648] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
[   30.044791] Call Trace:
[   30.045267]  <IRQ>
[   30.046157]  dump_stack+0x79/0xab:
						dump_stack at lib/dump_stack.c:55
[   30.046661]  __report_bad_irq+0x3e/0xbb:
						__report_bad_irq at kernel/irq/spurious.c:208
[   30.047213]  note_interrupt+0x1ab/0x239:
						note_interrupt at kernel/irq/spurious.c:421
[   30.047764]  handle_irq_event_percpu+0x41/0x47:
						handle_irq_event_percpu at kernel/irq/handle.c:194
[   30.048424]  handle_irq_event+0x39/0x5a:
						handle_irq_event at kernel/irq/handle.c:206
[   30.049013]  handle_edge_irq+0xc4/0xe6:
						handle_edge_irq at kernel/irq/chip.c:796
[   30.049582]  handle_irq+0xef/0xf7:
						handle_irq at arch/x86/kernel/irq_64.c:78
[   30.050087]  do_IRQ+0x7a/0xe5:
						do_IRQ at arch/x86/kernel/irq.c:241
[   30.050541]  common_interrupt+0x96/0x96:
						ret_from_intr at arch/x86/entry/entry_64.S:607
[   30.051089]  </IRQ>
[   30.051444] RIP: 0010:arch_local_irq_restore+0x2/0x8:
						arch_local_irq_restore at arch/x86/include/asm/paravirt.h:777
						
[   30.052166] RSP: 0018:ffffb1750342bd38 EFLAGS: 00000282 ORIG_RAX: ffffffffffffffc6
[   30.053273] RAX: ffff9f89b4f642c0 RBX: 0000000000000282 RCX: ffff9f89d2e0e307
[   30.054242] RDX: ffff9f89d2e0e306 RSI: ffff9f89b4f64c30 RDI: 0000000000000282
[   30.055196] RBP: ffffffffa625b870 R08: 00000009df72d6bb R09: 0000000000000001
[   30.056126] R10: ffff9f89b4f642c0 R11: 0000000000000000 R12: 0000000000000282
[   30.057091] R13: ffff9f89da1232f8 R14: ffff9f89a461e240 R15: 0000000000000001
[   30.058039]  _raw_spin_unlock_irqrestore+0x4a/0x54:
						__preempt_count_sub at arch/x86/include/asm/preempt.h:88
						 (inlined by) __raw_spin_unlock_irqrestore at include/linux/spinlock_api_smp.h:161
						 (inlined by) _raw_spin_unlock_irqrestore at kernel/locking/spinlock.c:191
[   30.058765]  uart_start+0x47/0x5c:
						uart_start at drivers/tty/serial/serial_core.c:135 (discriminator 1)
[   30.059260]  n_tty_write+0x131/0x410:
						n_tty_write at drivers/tty/n_tty.c:2337
[   30.059784]  ? prepare_to_wait+0x71/0x71:
						woken_wake_function at kernel/sched/wait.c:435
[   30.060390]  tty_write+0x1a7/0x23a:
						do_tty_write at drivers/tty/tty_io.c:950
						 (inlined by) tty_write at drivers/tty/tty_io.c:1033
[   30.060922]  ? n_tty_flush_buffer+0x49/0x49:
						n_tty_write at drivers/tty/n_tty.c:2272
[   30.061564]  __vfs_write+0x21/0xa7:
						__vfs_write at fs/read_write.c:480
[   30.062113]  ? _raw_spin_unlock_irq+0x2e/0x37:
						__preempt_count_sub at arch/x86/include/asm/preempt.h:88
						 (inlined by) __raw_spin_unlock_irq at include/linux/spinlock_api_smp.h:169
						 (inlined by) _raw_spin_unlock_irq at kernel/locking/spinlock.c:199
[   30.062805]  ? finish_task_switch+0x166/0x1d3:
						finish_task_switch at kernel/sched/core.c:2671
[   30.063481]  vfs_write+0xb8/0xf5:
						vfs_write at fs/read_write.c:545
[   30.064029]  SyS_write+0x50/0x7e
[   30.064569]  entry_SYSCALL_64_fastpath+0x1f/0x96:
						entry_SYSCALL_64_fastpath at arch/x86/entry/entry_64.S:206
[   30.065262] RIP: 0033:0x7fa1369040c0
[   30.065818] RSP: 002b:00007ffe2ab56918 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[   30.066828] RAX: ffffffffffffffda RBX: 0000000000000046 RCX: 00007fa1369040c0
[   30.067740] RDX: 0000000000000001 RSI: 00007fa136bc66a3 RDI: 0000000000000001
[   30.068652] RBP: 00007fa136bc66a3 R08: 00007fa136bc7780 R09: 00007fa136bc6620
[   30.069668] R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000001
[   30.070667] R13: 0000000000000001 R14: 00007fa136bc6620 R15: 000000000060c3f7
[   30.071657] handlers:
[   30.072081] [<ffffffffa1978a5e>] serial8250_interrupt
[   30.072841] Disabling IRQ #3

Attached the full dmesg, kconfig and reproduce scripts.

Thanks,
Fengguang