INFO: rcu_sched self-detected stall on CPU
INFO: rcu_sched detected stalls on CPUs/tasks:
	0-....: (125000 ticks this GP) idle=766/140000000000001/0 softirq=12167/12167 fqs=31230 
	(detected by 1, t=125002 jiffies, g=6389, c=6388, q=432)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 5332 Comm: syz-executor4 Not tainted 4.15.0-rc5+ #244
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:ffff8801db206ff0 EFLAGS: 00000003
RAX: 0000005a40cdb7b3 RBX: ffffffff8885df20 RCX: 0000005a40cdb0e8
RDX: 00000000000006cb RSI: 0000000000000000 RDI: 00000000000008fd
RBP: ffff8801db206ff0 R08: 1ffff1003b640d57 R09: 000000000000000c
R10: ffff8801db206f78 R11: 0000000000000040 R12: 0000000000002705
R13: 0000000000000020 R14: fffffbfff110bc29 R15: fffffbfff110bbed
FS:  00007f2567317700(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020266017 CR3: 00000001c147d006 CR4: 00000000001606f0
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:1179
 __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:920
 </IRQ>
RIP: 0010:mulaw_decode+0x550/0x770 sound/core/oss/mulaw.c:193
RSP: 0018:ffff8801c573f8b0 EFLAGS: 00000217 ORIG_RAX: ffffffffffffff11
RAX: 00000000000003c2 RBX: ffffc9000125dc3d RCX: 0000000000000000
RDX: 0000000000000002 RSI: ffff8801c573f972 RDI: ffffc9000125887a
RBP: ffff8801c573f9d8 R08: fffff5200024b110 R09: fffff5200024b110
R10: 0000000000000001 R11: fffff5200024b10f R12: 0000000000000002
R13: ffff8801cad95900 R14: dffffc0000000000 R15: ffffc9000125887a
 mulaw_transfer+0x222/0x270 sound/core/oss/mulaw.c:273
 snd_pcm_plug_write_transfer+0x22d/0x420 sound/core/oss/pcm_plugin.c:611
 snd_pcm_oss_write2+0x260/0x420 sound/core/oss/pcm_oss.c:1311
 snd_pcm_oss_write1 sound/core/oss/pcm_oss.c:1372 [inline]
 snd_pcm_oss_write+0x5fe/0x830 sound/core/oss/pcm_oss.c:2646
 __vfs_write+0xef/0x970 fs/read_write.c:480
 vfs_write+0x189/0x510 fs/read_write.c:544
 SYSC_write fs/read_write.c:589 [inline]
 SyS_write+0xef/0x220 fs/read_write.c:581
 entry_SYSCALL_64_fastpath+0x23/0x9a
RIP: 0033:0x452ac9
RSP: 002b:00007f2567316c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452ac9
RDX: 00000000fffffc98 RSI: 000000002025e000 RDI: 0000000000000013
RBP: 00000000000003c7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f3b48
R13: 00000000ffffffff R14: 00007f25673176d4 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 71 9a 7a f3 90 <65> ff 05 f8 70 9a 7a 65 8b 15 d1 04 9a 7a 39 f2 74 ce 48 29 c1 
	0-....: (125000 ticks this GP) idle=766/140000000000001/0 softirq=12167/12167 fqs=31413 
	 (t=125735 jiffies g=6389 c=6388 q=432)
NMI backtrace for cpu 0
CPU: 0 PID: 5332 Comm: syz-executor4 Not tainted 4.15.0-rc5+ #244
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
 n