INFO: task syz-executor7:26133 blocked for more than 140 seconds.
      Not tainted 4.18.0-rc8-next-20180807+ #33
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor7   D24032 26133   4329 0x00000004
Call Trace:
 context_switch kernel/sched/core.c:2823 [inline]
 __schedule+0x87c/0x1ec0 kernel/sched/core.c:3471
 schedule+0xfb/0x450 kernel/sched/core.c:3515
 schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:3573
 __mutex_lock_common kernel/locking/mutex.c:1003 [inline]
 __mutex_lock+0xbf9/0x1700 kernel/locking/mutex.c:1073
 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1088
 snd_pcm_oss_open+0x6d0/0x17a0 sound/core/oss/pcm_oss.c:2503
 soundcore_open+0x508/0x6d0 sound/sound_core.c:597
 chrdev_open+0x25a/0x770 fs/char_dev.c:417
 do_dentry_open+0x49c/0x1140 fs/open.c:771
 vfs_open+0xa0/0xd0 fs/open.c:880
 do_last fs/namei.c:3418 [inline]
 path_openat+0x12fb/0x5300 fs/namei.c:3534
 do_filp_open+0x255/0x380 fs/namei.c:3564
 do_sys_open+0x584/0x720 fs/open.c:1063
 __do_sys_open fs/open.c:1081 [inline]
 __se_sys_open fs/open.c:1076 [inline]
 __x64_sys_open+0x7e/0xc0 fs/open.c:1076
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4109f1
Code: a8 00 00 00 48 8b 5c 24 38 48 29 da 48 29 d1 48 89 88 68 01 00 00 0f b6 44 24 2e 84 c0 74 1b 0f b6 05 83 ff 05 01 84 c0 74 0a <8b> 05 b5 d2 05 01 85 c0 74 4c 31 c0 84 c0 75 1d 48 8b 44 24 40 48
RSP: 002b:00007fef595a17a0 EFLAGS: 00000293 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 6666666666666667 RCX: 00000000004109f1
RDX: 0000000000000000 RSI: 0000000000022002 RDI: 00007fef595a1850
RBP: 00000000009301e0 R08: 000000000000000f R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 00000000ffffffff
R13: 00000000004d5f58 R14: 00000000004c9814 R15: 0000000000000002
INFO: lockdep is turned off.
NMI backtrace for cpu 0
CPU: 0 PID: 774 Comm: khungtaskd Not tainted 4.18.0-rc8-next-20180807+ #33
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113
 nmi_cpu_backtrace.cold.3+0x48/0x88 lib/nmi_backtrace.c:101
 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_all_cpu_backtrace include/linux/nmi.h:144 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:204 [inline]
 watchdog+0xb39/0x10b0 kernel/hung_task.c:265
 kthread+0x35a/0x420 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:415
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 2290 Comm: udevd Not tainted 4.18.0-rc8-next-20180807+ #33
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:list_splice_init include/linux/list.h:367 [inline]
RIP: 0010:ep_scan_ready_list+0x2cf/0x1090 fs/eventpoll.c:701
Code: ef 03 48 89 83 00 fe ff ff 49 be 00 00 00 00 00 fc ff df 43 c6 04 37 f8 48 39 85 28 fd ff ff 0f 84 7b 01 00 00 e8 41 b7 9f ff <48> 8b 85 20 fd ff ff 48 c1 e8 03 42 80 3c 30 00 0f 85 67 0c 00 00
RSP: 0018:ffff8801ca5f7668 EFLAGS: 00000093
RAX: ffff8801ca5e82c0 RBX: ffff8801ca5f7968 RCX: 1ffff100394beeed
RDX: 0000000000000000 RSI: ffffffff81dd766f RDI: ffff8801ca40fb40
RBP: ffff8801ca5f7990 R08: ffffed0039481f69 R09: ffffed0039481f68
R10: ffffed0039481f68 R11: ffff8801ca40fb43 R12: ffffffff81ddc660
R13: ffff8801ca5f7b28 R14: dffffc0000000000 R15: 1ffff100394beeed
FS:  00007f795b6d07a0(0000) GS:ffff8801db100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffff600400 CR3: 00000001ca4f5000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 ep_send_events fs/eventpoll.c:1713 [inline]
 ep_poll+0x59c/0x1430 fs/eventpoll.c:1840
 do_epoll_wait+0x1b0/0x200 fs/eventpoll.c:2198
 __do_sys_epoll_wait fs/eventpoll.c:2208 [inline]
 __se_sys_epoll_wait fs/eventpoll.c:2205 [inline]
 __x64_sys_epoll_wait+0x97/0xf0 fs/eventpoll.c:2205
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f795ade4943
Code: 00 31 d2 48 29 c2 64 89 11 48 83 c8 ff eb ea 90 90 90 90 90 90 90 90 83 3d b5 dc 2a 00 00 75 13 49 89 ca b8 e8 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 34 c3 48 83 ec 08 e8 3b c4 00 00 48 89 04 24
RSP: 002b:00007ffec8ffcef8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e8
RAX: ffffffffffffffda RBX: 0000000000000bb8 RCX: 00007f795ade4943
RDX: 0000000000000008 RSI: 00007ffec8ffcff0 RDI: 000000000000000a
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000bb8 R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000000000 R14: 0000000001354350 R15: 000000000133b250