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

1 Jul 2025

On Mon, Jun 30, 2025 at 02:25:23PM -0600, Keith Busch wrote:
...
On Mon, Jun 30, 2025 at 03:33:43PM +0200, Christoph Hellwig wrote:

--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -701,7 +701,7 @@ static void nvme_free_prps(struct request *req)
        prp_list = iod->descriptors[desc];
        do {
                dma_unmap_page(dma_dev, dma_addr, dma_len, dir);

          if (i == NVME_CTRL_PAGE_SIZE >> 3) {




          if (i == NVME_CTRL_PAGE_SIZE >> 3 && length > NVME_CTRL_PAGE_SIZE) {
                  prp_list = iod->descriptors[++desc];
                  i = 0;
          }



--
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 [...]
Err, I meant to say "dma_unmap_page()".

    