next-20250627: IOMMU DMA warning during NVMe I/O completion after 06cae0e3f61c

[Leon Romanovsky]

On Tue, Jul 01, 2025 at 03:29:36PM +0200, Christoph Hellwig wrote:
> On Mon, Jun 30, 2025 at 02:25:23PM -0600, Keith Busch wrote:
> > I think the PRP handling is broken. At the very least, handling the last
> > element is wrong if it appears at the end of the list, so I think we
> > need something like this:
> 
> Yeah.
> 
> > But even that, the PRP setup doesn't match the teardown. We're calling
> > dma_map_page() on each PRP even if consecutive PRP's came from the same
> > dma mapping segment. So even if it had been coalesced, but if the device
> > doesn't support SGLs, then it would use the prp unmap path.
> 
> Yes, that's broken, and I remember fixing it before.  A little digging
> shows that my fixes disappeared between the oct 30 version of Leon's
> dma-split branch and the latest one somewhere.

Oct, 30 belongs to RFC/first version of patches.

Thanks