kernel BUG at nvme/host/pci.c

[Sagi Grimberg]

>>> nomerges set to 1 on both devices, same BUG_ON.
>> Thanks for the info.
>>
>> Could you possibly recreate with the patch below? This will simply
>> return IO error rather the panic, and show exactly how this invalid SGL
>> is constructed.
> Won't compile with 4.12.0, since BLK_STS_* and blk_status_t aren't present.
> Got the latest sources from git, applied the patch and earned "Invalid
> SGL for payload:36864 nents:7". System is badly yelling about i/o errors
> on NVME, so I rebooted.

I think if we iterated on the sgls logging their dma_address, offset and
length it'd be more useful.