kern/51979: kernel crash dump to wd0b failed

[martin%NetBSD.org@localhost]

>Number:         51979
>Category:       kern
>Synopsis:       kernel crash dump to wd0b failed
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Feb 17 19:00:00 +0000 2017
>Originator:     Martin Husemann
>Release:        NetBSD 7.99.60
>Organization:
The NetBSD Foundation, Inc.
>Environment:
System: NetBSD night-owl.duskware.de 7.99.60 NetBSD 7.99.60 (NIGHT-OWL) #483: Fri Feb 17 13:49:36 CET 2017 martin%night-owl.duskware.de@localhost:/usr/src/sys/arch/amd64/compile/NIGHT-OWL amd64
Architecture: x86_64
Machine: amd64
>Description:

My kernel crashed but I could not get a dump written:
(manual transcript:)

dumping to dev 0,1 (offset=4481543, size=1012867):
dump panic: wddump: polled command has been queued
..

Dmesg fragment for wd0 is:

ahcisata0 at pci0 dev 31 function 2: vendor 8086 product 3b29 (rev. 0x05)
ahcisata0: interrupting at ioapic0 pin 19
ahcisata0: 64-bit DMA
ahcisata0: AHCI revision 1.30, 4 ports, 32 slots, CAP 0xff20ff63<SXS,EMS,PSC,SSC,PMD,ISS=0x2=Gen2,SCLO,SAL,SALP,SSS,SMPS,SSNTF,SNCQ,S64A>
atabus0 at ahcisata0 channel 0
atabus1 at ahcisata0 channel 1
atabus2 at ahcisata0 channel 4
atabus3 at ahcisata0 channel 5
ahcisata0 port 0: device present, speed: 3.0Gb/s
ahcisata0 port 4: device present, speed: 1.5Gb/s
acpiacad0: AC adapter online.
wd0 at atabus0 drive 0
wd0: <Hitachi HTS545050B9A300>
wd0: drive supports 16-sector PIO transfers, LBA48 addressing
wd0: 465 GB, 969021 cyl, 16 head, 63 sec, 512 bytes/sect x 976773168 sectors
wd0: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 6 (Ultra/133)
wd0(ahcisata0:0:0): using PIO mode 4, DMA mode 2, Ultra-DMA mode 6 (Ultra/133) (using DMA)

It used to work recentish (after maya fixed the off by one in sparse dumps)

>How-To-Repeat:
n/a

>Fix:
n/a