syzbot hit the following crash on upstream commit
e02d37bf55a9a36f22427fd6dd733fe104d817b6 (Thu Apr 5 17:42:07 2018 +0000)
Merge tag 'sound-4.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound syzbot dashboard link: https://syzkaller.appspot.com/bug?extid=150189c103427d31a053

So far this crash happened 3 times on upstream.
Unfortunately, I don't have any reproducer for this crash yet.
Raw console output: https://syzkaller.appspot.com/x/log.txt?id=6067392849379328 Kernel config: https://syzkaller.appspot.com/x/.config?id=-4805825610197092128
compiler: gcc (GCC) 8.0.1 20180301 (experimental)

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Reported-by: syzbot+150189c103427d31a...@syzkaller.appspotmail.com
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Buffer I/O error on dev loop0, logical block 6, lost async page write
Buffer I/O error on dev loop0, logical block 7, lost async page write
Buffer I/O error on dev loop0, logical block 8, lost async page write
Buffer I/O error on dev loop0, logical block 9, lost async page write
Buffer I/O error on dev loop0, logical block 10, lost async page write
INFO: rcu_sched self-detected stall on CPU
1-....: (124998 ticks this GP) idle=9b2/1/4611686018427387906 softirq=22733/22733 fqs=31170
         (t=125000 jiffies g=11599 c=11598 q=1619)
NMI backtrace for cpu 1
CPU: 1 PID: 7184 Comm: syz-executor3 Not tainted 4.16.0+ #2
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b9/0x29f lib/dump_stack.c:53
 nmi_cpu_backtrace.cold.4+0x19/0xce lib/nmi_backtrace.c:103
 nmi_trigger_cpumask_backtrace+0x151/0x192 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+0x175/0x1c2 kernel/rcu/tree.c:1376
 print_cpu_stall kernel/rcu/tree.c:1525 [inline]
 check_cpu_stall.isra.61.cold.80+0x36c/0x59a kernel/rcu/tree.c:1593
 __rcu_pending kernel/rcu/tree.c:3356 [inline]
 rcu_pending kernel/rcu/tree.c:3401 [inline]
 rcu_check_callbacks+0x21b/0xad0 kernel/rcu/tree.c:2763
 update_process_times+0x2d/0x70 kernel/time/timer.c:1636
 tick_sched_handle+0xa0/0x180 kernel/time/tick-sched.c:171
 tick_sched_timer+0x42/0x130 kernel/time/tick-sched.c:1179
 __run_hrtimer kernel/time/hrtimer.c:1337 [inline]
 __hrtimer_run_queues+0x3e3/0x10a0 kernel/time/hrtimer.c:1399
 hrtimer_interrupt+0x286/0x650 kernel/time/hrtimer.c:1457
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline]
 smp_apic_timer_interrupt+0x15d/0x710 arch/x86/kernel/apic/apic.c:1050
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:862
RIP: 0010:__sanitizer_cov_trace_pc+0x2b/0x50 kernel/kcov.c:101
RSP: 0018:ffff8801cfe77710 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: ffff8801d0108080 RBX: 0000000000000004 RCX: ffffffff85a1f955
RDX: 0000000000000002 RSI: ffffffff85a1f95f RDI: 0000000000000005
RBP: ffff8801cfe77710 R08: ffff8801d0108080 R09: 0000000000000006
R10: ffff8801d0108080 R11: 0000000000000000 R12: 0000000000000001
R13: ffff8801ceb2cd80 R14: ffff8801aaacec00 R15: ffffffffffffffe0
 snd_pcm_oss_write3+0x16f/0x220 sound/core/oss/pcm_oss.c:1224
 io_playback_transfer+0x274/0x310 sound/core/oss/io.c:47
 snd_pcm_plug_write_transfer+0x36c/0x470 sound/core/oss/pcm_plugin.c:619
 snd_pcm_oss_write2+0x25c/0x460 sound/core/oss/pcm_oss.c:1365
 snd_pcm_oss_sync1+0x332/0x5a0 sound/core/oss/pcm_oss.c:1606
 snd_pcm_oss_sync.isra.29+0x790/0x980 sound/core/oss/pcm_oss.c:1682
 snd_pcm_oss_release+0x214/0x290 sound/core/oss/pcm_oss.c:2559
 __fput+0x34d/0x890 fs/file_table.c:209
 ____fput+0x15/0x20 fs/file_table.c:243
 task_work_run+0x1e4/0x290 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x2bd/0x310 arch/x86/entry/common.c:166
 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
 do_syscall_64+0x792/0x9d0 arch/x86/entry/common.c:292
RIP: 0033:0x4552d9
RSP: 002b:00007f4e5ffe6c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00007f4e5ffe76d4 RCX: 00000000004552d9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000013
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000052 R14: 00000000006f3850 R15: 0000000000000000
INFO: rcu_sched detected expedited stalls on CPUs/tasks: { 1-... } 127452 jiffies s: 2685 root: 0x2/.
blocking rcu_node structures:
Task dump for CPU 1:
syz-executor3   R  running task    24120  7184   4559 0x0000000c
Call Trace:

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