On 6/30/2025 1:20 PM, Ben Copeland wrote:
# first bad commit: [06cae0e3f61c4c1ef18726b817bbb88c29f81e57] nvme-pci: merge the simple PRP and SGL setup into a common helper
this patch had the problem [0] of not setting 'iod->first_dma' which can trigger that IOMMU warning on unmap. But problem was transient as a subsequent patch removed the iod->first_dma and made unmapping work without that.
[0] -static blk_status_t nvme_setup_prp_simple(struct nvme_dev *dev, - struct request *req, struct nvme_rw_command *cmnd, - struct bio_vec *bv) +static blk_status_t nvme_pci_setup_data_simple(struct request *req, + enum nvme_use_sgl use_sgl) { struct nvme_iod *iod = blk_mq_rq_to_pdu(req); - unsigned int offset = bv->bv_offset & (NVME_CTRL_PAGE_SIZE - 1); - unsigned int first_prp_len = NVME_CTRL_PAGE_SIZE - offset; - - iod->first_dma = dma_map_bvec(dev->dev, bv, rq_dma_dir(req), 0); - if (dma_mapping_error(dev->dev, iod->first_dma))
iod->first_dma does not get set, and that can cause unmap on invalid address during teardown.