TITLE: INFO: rcu detected stall in snd_seq_write
TYPE: HANG

[  599.875361] rcu: INFO: rcu_sched self-detected stall on CPU
[  599.881199] rcu: 	0-....: (105000 ticks this GP) idle=2f6/1/0x4000000000000002 softirq=23001/23001 fqs=26239 
[  599.891361] rcu: 	 (t=105008 jiffies g=49145 q=2382)
[  599.896509] NMI backtrace for cpu 0
[  599.900150] CPU: 0 PID: 8551 Comm: syz-executor7 Not tainted 4.18.0-next-20180824+ #47
[  599.908198] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
[  599.917548] Call Trace:
[  599.920132]  <IRQ>
[  599.922286]  dump_stack+0x1c9/0x2b4
[  599.944682]  nmi_cpu_backtrace.cold.3+0x48/0x88
[  599.954558]  nmi_trigger_cpumask_backtrace+0x151/0x192
[  599.959858]  arch_trigger_cpumask_backtrace+0x14/0x20
[  599.965052]  rcu_dump_cpu_stacks+0x175/0x1c2
[  599.974486]  print_cpu_stall.cold.78+0x2fb/0x59c
[  599.995787]  rcu_check_callbacks+0xd4a/0x15a0
[  600.093087]  update_process_times+0x2d/0x70
[  600.097415]  tick_sched_handle+0x9f/0x180
[  600.101564]  tick_sched_timer+0x45/0x130
[  600.105627]  __hrtimer_run_queues+0x3eb/0xff0
[  600.150990]  hrtimer_interrupt+0x2f3/0x750
[  600.155241]  smp_apic_timer_interrupt+0x16d/0x6a0
[  600.207857]  apic_timer_interrupt+0xf/0x20
[  600.212089]  </IRQ>
[  600.214345] RIP: 0010:lock_release+0xa2/0x9f0
[  600.237744] RSP: 0018:ffff8801aa0078c8 EFLAGS: 00000292 ORIG_RAX: ffffffffffffff13
[  600.245455] RAX: 2ec5cd2493d34200 RBX: 1ffff10035400f1e RCX: 0000000000000000
[  600.252724] RDX: dffffc0000000000 RSI: 0000000000000000 RDI: ffff8801a9b56bbc
[  600.259994] RBP: ffff8801aa0079f8 R08: 00000000000010df R09: 0000000000000001
[  600.267263] R10: ffff8801a9b56be8 R11: 737c3e5c87308161 R12: ffff8801aa0079d0
[  600.274530] R13: ffff8801c778d4c8 R14: ffff8801aa007ae0 R15: ffff8801a9b56380
[  600.307088]  __might_fault+0x19e/0x1e0
[  600.310986]  _copy_from_user+0x30/0x150
[  600.315053]  snd_seq_write+0x472/0x8d0
[  600.332960]  __vfs_write+0x117/0x9d0
[  600.379161]  vfs_write+0x1fc/0x560
[  600.382717]  ksys_write+0x101/0x260
[  600.390441]  __x64_sys_write+0x73/0xb0
[  600.398306]  do_syscall_64+0x1b9/0x820
[  600.436382]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  600.441569] RIP: 0033:0x457089
[  600.463760] RSP: 002b:00007f09af65dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[  600.471476] RAX: ffffffffffffffda RBX: 00007f09af65e6d4 RCX: 0000000000457089
[  600.478757] RDX: 00000000ffffff76 RSI: 0000000020000000 RDI: 0000000000000003
[  600.486032] RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000
[  600.493302] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
[  600.500573] R13: 00000000004d78a8 R14: 00000000004ca886 R15: 0000000000000000