INFO: rcu_sched self-detected stall on CPU
INFO: rcu_sched detected stalls on CPUs/tasks:
	1-....: (125000 ticks this GP) idle=e36/1/4611686018427387906 softirq=10780/10780 fqs=31226 
	(detected by 0, t=125002 jiffies, g=5388, c=5387, q=342)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4945 Comm: syz-executor2 Not tainted 4.15.0-rc6-mm1+ #50
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+0x6b/0x90 drivers/tty/serial/8250/8250_port.c:434
RSP: 0018:ffff8801db5078d0 EFLAGS: 00000002
RAX: dffffc0000000000 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: 0000000000000005 RDI: ffffffff87e4e018
RBP: ffff8801db5078e0 R08: ffffffff82547f25 R09: 000000000000000c
R10: ffff8801db5078f8 R11: 0000000000000001 R12: ffffffff87e4dfe0
R13: 0000000000000020 R14: fffffbfff0fc9c41 R15: fffffbfff0fc9c05
FS:  00007f9197b63700(0000) GS:ffff8801db500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020cc6ff4 CR3: 00000001c94dc001 CR4: 00000000001606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 serial_in drivers/tty/serial/8250/8250.h:111 [inline]
 wait_for_xmitr+0x93/0x1e0 drivers/tty/serial/8250/8250_port.c:2033
 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+0x5b3/0x940 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+0x6ba/0xc30 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:1686 [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+0xb68/0x1de0 kernel/rcu/tree.c:2764
 update_process_times+0x30/0x60 kernel/time/timer.c:1628
 tick_sched_handle+0x85/0x160 kernel/time/tick-sched.c:162
 tick_sched_timer+0x42/0x120 kernel/time/tick-sched.c:1176
 __run_hrtimer kernel/time/hrtimer.c:1210 [inline]
 __hrtimer_run_queues+0x2c8/0xb50 kernel/time/hrtimer.c:1274
 hrtimer_interrupt+0x1c2/0x5e0 kernel/time/hrtimer.c:1308
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline]
 smp_apic_timer_interrupt+0xc9/0x4c0 arch/x86/kernel/apic/apic.c:1050
 apic_timer_interrupt+0xa9/0xb0 arch/x86/entry/entry_64.S:920
 </IRQ>
RIP: 0010:cvt_s16_to_native sound/core/oss/mulaw.c:159 [inline]
RIP: 0010:mulaw_decode+0x404/0x740 sound/core/oss/mulaw.c:195
RSP: 0018:ffff8801c95cf948 EFLAGS: 00000a02 ORIG_RAX: ffffffffffffff11
RAX: 1ffff10039d1f194 RBX: ffffc900012ab63c RCX: ffffffff83b7d122
RDX: 0000000000010000 RSI: ffffc90003436000 RDI: ffffc900012a0c78
RBP: ffff8801c95cfa68 R08: fffff5200025418f R09: fffff5200025418f
R10: 0000000000000001 R11: fffff5200025418e R12: 00000000ffff8284
R13: ffffc900012a0c78 R14: ffff8801ce8f8c00 R15: dffffc0000000000
 mulaw_transfer+0x222/0x270 sound/core/oss/mulaw.c:273
 snd_pcm_plug_write_transfer+0x20b/0x390 sound/core/oss/pcm_plugin.c:611
 snd_pcm_oss_write2+0x22e/0x3c0 sound/core/oss/pcm_oss.c:1311
 snd_pcm_oss_write1 sound/core/oss/pcm_oss.c:1372 [inline]
 snd_pcm_oss_write+0x4c1/0x690 sound/core/oss/pcm_oss.c:2646
 __vfs_write+0xef/0x740 fs/read_write.c:480
 vfs_write+0x189/0x510 fs/read_write.c:544
 SYSC_write fs/read_write.c:589 [inline]
 SyS_write+0xd4/0x1a0 fs/read_write.c:581
 entry_SYSCALL_64_fastpath+0x23/0x9a
RIP: 0033:0x452ac9
RSP: 002b:00007f9197b62c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f9197b63700 RCX: 0000000000452ac9
RDX: 00000000ffffffa2 RSI: 0000000020001000 RDI: 0000000000000015
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 0000000000000000
R13: 0000000000a2f7ef R14: 00007f9197b639c0 R15: 0000000000000000
Code: 24 d1 00 00 00 49 8d 7c 24 38 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 d3 e3 80 3c 02 00 75 17 41 03 5c 24 38 89 da ec <5b> 0f b6 c0 41 5c 5d c3 e8 08 54 36 ff eb c2 e8 61 54 36 ff eb 
	1-....: (125000 ticks this GP) idle=e36/1/4611686018427387906 softirq=10780/10780 fqs=31356 
	 (t=125523 jiffies g=5388 c=5387 q=342)
NMI backtrace for cpu 1
CPU: 1 PID: 4945 Comm: syz-executor2 Not tainted 4.15.0-rc6-mm1+ #50
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+0x137/0x198 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+0x186/0x1d7 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+0x1a64/0x1de0 kernel/rcu/tree.c:2764
 update_process_times+0x30/0x60 kernel/time/timer.c:1628
 tick_sched_handle+0x85/0x160 kernel/time/tick-sched.c:162
 tick_sched_timer+0x42/0x120 kernel/time/tick-sched.c:1176
 __run_hrtimer kernel/time/hrtimer.c:1210 [inline]
 __hrtimer_run_queues+0x2c8/0xb50 kernel/time/hrtimer.c:1274
 hrtimer_interrupt+0x1c2/0x5e0 kernel/time/hrtimer.c:1308
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline]
 smp_apic_timer_interrupt+0xc9/0x4c0 arch/x86/kernel/apic/apic.c:1050
 apic_timer_interrupt+0xa9/0xb0 arch/x86/entry/entry_64.S:920
 </IRQ>
RIP: 0010:cvt_s16_to_native sound/core/oss/mulaw.c:159 [inline]
RIP: 0010:mulaw_decode+0x404/0x740 sound/core/oss/mulaw.c:195
RSP: 0018:ffff8801c95cf948 EFLAGS: 00000a02 ORIG_RAX: ffffffffffffff11
RAX: 1ffff10039d1f194 RBX: ffffc900012ab63c RCX: ffffffff83b7d122
RDX: 0000000000010000 RSI: ffffc90003436000 RDI: ffffc900012a0c78
RBP: ffff8801c95cfa68 R08: fffff5200025418f R09: fffff5200025418f
R10: 0000000000000001 R11: fffff5200025418e R12: 00000000ffff8284
R13: ffffc900012a0c78 R14: ffff8801ce8f8c00 R15: dffffc0000000000
 mulaw_transfer+0x222/0x270 sound/core/oss/mulaw.c:273
 snd_pcm_plug_write_transfer+0x20b/0x390 sound/core/oss/pcm_plugin.c:611
 snd_pcm_oss_write2+0x22e/0x3c0 sound/core/oss/pcm_oss.c:1311
 snd_pcm_oss_write1 sound/core/oss/pcm_oss.c:1372 [inline]
 snd_pcm_oss_write+0x4c1/0x690 sound/core/oss/pcm_oss.c:2646
 __vfs_write+0xef/0x740 fs/read_write.c:480
 vfs_write+0x189/0x510 fs/read_write.c:544
 SYSC_write fs/read_write.c:589 [inline]
 SyS_write+0xd4/0x1a0 fs/read_write.c:581
 entry_SYSCALL_64_fastpath+0x23/0x9a
RIP: 0033:0x452ac9
RSP: 002b:00007f9197b62c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f9197b63700 RCX: 0000000000452ac9
RDX: 00000000ffffffa2 RSI: 0000000020001000 RDI: 0000000000000015
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 0000000000000000
R13: 0000000000a2f7ef R14: 00007f9197b639c0 R15: 0000000000000000