[bug report] block/005 hangs with NVMe device and linux-block/for-next

[Damien Le Moal]

+linux-nvme (Keith and Christoph)


On 2021/11/02 17:19, Shinichiro Kawasaki wrote:
> On Nov 02, 2021 / 03:07, Chaitanya Kulkarni wrote:
>>
>>> The NVMe device I use is a U.2 NVMe ZNS SSD. It has a zoned name space and
>>> a regular name space, and the hang is observed with both name spaces. I have
>>> not yet tried other NVME devices, so I will try them.
> 
> I tried another NVMe device, WD Black SN750, but it did not recreate the hang.
> 
>>>
>>
>> See if you can produce this with QEMU NVMe emulation (ZNS and NON-ZNS
>> mode), if you can then it will be easier to reproduce for everyone.
> 
> Chaitanya, thank you for the advice. I have managed to reproduce the hang with
> QEMU NVMe emulation. Actually, ZNS mode is not required. I tried some device
> set up configuration with QEMU, and the hang was recreated when a single NVMe
> device has two namespaces. With single namespace in a single NVMe device, the
> hang is not observed.
> 
> So it looks like that the number of namespaces may be related to the cause. The
> WD Black SN750 without hang has single namespace. I reduced the number of
> namespaces of the U.2 NVMe ZNS SSD from 2 to 1, then the hang was not observed.
> 
> FYI, the QEMU command line options that I used was as follows. It prepares
> /dev/nvme0n1 and /dev/nvme0n2, and the block/005 run on /dev/nvme0n1 recreated
> the hang.
> 
> -device nvme,id=nvme0,serial=qemunvme,logical_block_size=4096,physical_block_size=4096 \
> -drive file=(path)/nvme0n1.img,id=nvme0n1,format=raw,if=none \
> -device nvme-ns,drive=nvme0n1,bus=nvme0,nsid=1 \
> -drive file=(path)/nvme0n2.img,id=nvme0n2,format=raw,if=none \
> -device nvme-ns,drive=nvme0n2,bus=nvme0,nsid=2
> 
> Regarding the two image files, I created them beforehand with the command below:
> 
> $ qemu-img create -f raw "${image_file_path}" 1024M
> 
> Hope this helps.
> 



-- 
Damien Le Moal
Western Digital Research