Message-ID: <f4f5e80803d011926505692cda06@google.com>
Date:   Fri, 06 Apr 2018 05:04:01 -0700
From:   syzbot <syzbot+adc909755650e074e501@...kaller.appspotmail.com>
To:     akpm@...ux-foundation.org, aryabinin@...tuozzo.com,
        dvyukov@...gle.com, gregkh@...uxfoundation.org,
        kstewart@...uxfoundation.org, linux-kernel@...r.kernel.org,
        syzkaller-bugs@...glegroups.com, tchibo@...gle.com
Subject: INFO: rcu detected stall in snd_pcm_oss_write2

Hello,

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=adc909755650e074e501

So far this crash happened 2 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=4567980574769152
Kernel config:  
https://syzkaller.appspot.com/x/.config?id=-4805825610197092128
compiler: gcc (GCC) 8.0.1 20180301 (experimental)

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+adc909755650e074e501@...kaller.appspotmail.com
It will help syzbot understand when the bug is fixed. See footer for  
details.
If you forward the report, please keep this part and the footer.

         reason=80000021 qualification=0000000000000000
IDTVectoring: info=00000000 errcode=00000000
TSC Offset = 0xfffffd92e6bf78df
TPR Threshold = 0x00
EPT pointer = 0x00000001ab93b01e
INFO: rcu_sched self-detected stall on CPU
	0-....: (124999 ticks this GP) idle=81a/1/4611686018427387906  
softirq=379270/379270 fqs=31240
	 (t=125000 jiffies g=195733 c=195732 q=734)
NMI backtrace for cpu 0
CPU: 0 PID: 9961 Comm: syz-executor2 Not tainted 4.16.0+ #2
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+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
  </IRQ>
RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x0/0x20 kernel/kcov.c:183
RSP: 0018:ffff88018e3fee20 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff85a132bd
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff88018e3fee70 R08: ffff88018e044100 R09: 0000000000000006
R10: ffff88018e044100 R11: 0000000000000000 R12: 0000000000000001
R13: ffff8801ceaa2d80 R14: ffff88019269ab00 R15: ffffffffffffffe0
  snd_pcm_oss_write2+0x34c/0x460 sound/core/oss/pcm_oss.c:1373
  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
  exit_task_work include/linux/task_work.h:22 [inline]
  do_exit+0x1aee/0x2730 kernel/exit.c:865
  do_group_exit+0x16f/0x430 kernel/exit.c:968
  get_signal+0x886/0x1960 kernel/signal.c:2469
  do_signal+0x90/0x2020 arch/x86/kernel/signal.c:810
  exit_to_usermode_loop+0x28a/0x310 arch/x86/entry/common.c:162
  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
  entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x4552d9
RSP: 002b:00007f0bfca8cce8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000072bf80 RCX: 00000000004552d9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000072bf80
RBP: 000000000072bf80 R08: 0000000000000000 R09: 000000000072bf58
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000a3e81f R14: 00007f0bfca8d9c0 R15: 0000000000000001


---
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