[PATCH v4] nvme: fix corruption for passthrough meta/data

[Kanchan Joshi]

On 10/13/2023 10:56 AM, Christoph Hellwig wrote:
> On Fri, Oct 13, 2023 at 10:44:58AM +0530, Kanchan Joshi wrote:
>> Changes since v3:
>> - Block only unprivileged user
> 
> That's not really what at least I had in mind.  I'd much rather
> completely disable unprivileged passthrough for now as an easy
> backportable patch.  And then only re-enable it later in a way
> where it does require using SGLs for all data transfers.
> 

I did not get how forcing SGLs can solve the issue at hand.
The problem happened because (i) user specified short buffer/len, and 
(ii) kernel allocated buffer. Whether the buffer is fed to device using 
PRP or SGL does not seem to solve the large DMA problem.