kern/51746: Panics from audio

[coypu%sdf.org@localhost]

>Number:         51746
>Category:       kern
>Synopsis:       Panics from audio
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Dec 26 21:45:00 +0000 2016
>Originator:     coypu
>Release:        NetBSD 7.99.52
>Organization:
>Environment:
NetBSD box 7.99.52 NetBSD 7.99.52 (GENERIC) #3: Sun Dec 25 12:52:45 IST 2016  fly@box:/home/fly/gcc3/sys/arch/amd64/compile/GENERIC amd64
>Description:
No coredump because those stopped working for me.

My pile of backtraces over time:



uvm_fault(0xfffffe838444c738, 0x2000, 1) -> e
fatal page fault in supervisor mode
trap type 6 code 0 rip ffffffff80648ade cs 8 rflags 10202 cr2 24a8 ilevel 8 rsp fffffe811dcbeba0
curlwp 0xfffffe8469ff68e0 pid 1455.870 lowest kstack 0xfffffe811dcbb2c0
panic: trap
cpu0: Begin traceback...
vpanic() at netbsd:vpanic+0x140
snprintf() at netbsd:snprintf
trap() at netbsd:trap+0xc76
--- trap (number 6) ---
audio_write() at netbsd:audio_write+0x173
audiowrite() at netbsd:audiowrite+0x5a
spec_write() at netbsd:spec_write+0xb2
VOP_WRITE() at netbsd:VOP_WRITE+0x37
vn_write() at netbsd:vn_write+0xec
dofilewrite() at netbsd:dofilewrite+0x97
sys_write() at netbsd:sys_write+0x5f
syscall() at netbsd:syscall+0x1df
--- syscall (number 4) ---
7ce9cee3ca2a:
cpu0: End traceback...



WARNING: SPL NOT LOWERED ON SYSCALL 1 4 EXIT 3ef0e000 7
netbsd:trap+0xc4b
--- trap (number 6) ---
audio_ioctl() at netbsd:audio_ioctl+0x4bf
audioioctl() at netbsd:audioioctl+0xcd
VOP_IOCTL() at netbsd:VOP_IOCTL+0x3b
vn_ioctl() at netbsd:vn_ioctl+0xa6
sys_ioctl() at netbsd:sys_ioctl+0x101
syscall() at netbsd:syscall+0x15b
--- syscall (number 54) ---
74fd3e900b3a:
cpu8: End traceback...
uvm_fault(0xfffffe8124749750, 0x2000, 1) -> e
fatal page fault in supervisor mode
trap type 6 code 0 rip ffffffff8064589b cs 8 rflags 10202 cr2 24a8 ilevel 8 rsp fffffe813057cba0
curlwp 0xfffffe8469fa84c0 pid 887.411 lowest kstack 0xfffffe81305792c0




trap type 6 code 0 rip ffffffff80648c08 cs 8 rflags 13202 cr2 64000003f8 ilevel 0 rsp fffffe80017deba0
curlwp 0xfffffe824c752940 pid 12099.1573 lowest kstack 0xfffffe80017db2c0
panic: trap
cpu0: Begin traceback...
vpanic() at netbsd:vpanic+0x140
snprintf() at netbsd:snprintf
trap() at netbsd:trap+0xc76
--- trap (number 6) ---
audio_write() at netbsd:audio_write+0x29d
audiowrite() at netbsd:audiowrite+0x5a
spec_write() at netbsd:spec_write+0xb2
VOP_WRITE() at netbsd:VOP_WRITE+0x37
vn_write() at netbsd:vn_write+0xec
dofilewrite() at netbsd:dofilewrite+0x97
sys_write() at netbsd:sys_write+0x5f
syscall() at netbsd:syscall+0x1df
--- syscall (number 4) ---
7f7ff6c3ca2a:
cpu0: End traceback...
uvm_fault(0xfffffe8403ab65c8, 0x0, 2) -> e
fatal page fault in supervisor mode
trap type 6 code 2 rip ffffffff8084c9ad cs 8 rflags 10286 cr2 c4 ilevel 8 rsp fffffe811de74b10
curlwp 0xfffffe83c31aeb20 pid 28137.1 lowest kstack 0xfffffe811de712c0


You get the point.
>How-To-Repeat:
Play audio.

Presumably play audio opening & closing the channel repeatedly, which happens "naturally" when playing from firefox.
>Fix: