On Wed, Aug 13, 2025 at 03:52:44PM -0600, Keith Busch wrote:

On Wed, Aug 13, 2025 at 05:23:47PM -0400, Martin K. Petersen wrote:

quoted

dma_alignment defines the alignment of the DMA starting address. We
don't have a dedicated queue limit for the transfer length granularity
described by NVMe.

Darn, but thanks for confirming. I'll see if I can get by without
needing a new limit, or look into adding one if not. Worst case, I can
also let the device return the error, though I think we prefer not to
send an IO that we know should fail.

Allowing an unprivileged user application to trivially trigger an I/O
error sounds like a bad idea.

But I think simply applying the dma_alignment to the length of
READ/WRITE commands might be work, while ignoring it for other types
of commands.