Hi!
[ Upstream commit fb4b1373dcab086d0619c29310f0466a0b2ceb8a ]
Function "dma_map_sg" is entitled to merge adjacent entries and return a value smaller than what was passed as "nents".
Subsequently "ib_map_mr_sg" needs to work with this value ("sg_dma_len") rather than the original "nents" parameter ("sg_len").
This old RDS bug was exposed and reliably causes kernel panics (using RDMA operations "rds-stress -D") on x86_64 starting with: commit c588072bba6b ("iommu/vt-d: Convert intel iommu driver to the iommu ops")
Simply put: Linux 5.11 and later.
I see this queued for 4.19 and 5.10 where "iommu/vt-d: Convert intel iommu driver to the iommu ops" is not present. It may be okay for older kernels, too, but I wanted to double-check.
Best regards, Pavel
+++ b/net/rds/ib_frmr.c @@ -112,9 +112,9 @@ static int rds_ib_post_reg_frmr(struct rds_ib_mr *ibmr) cpu_relax(); }
- ret = ib_map_mr_sg_zbva(frmr->mr, ibmr->sg, ibmr->sg_len,
- ret = ib_map_mr_sg_zbva(frmr->mr, ibmr->sg, ibmr->sg_dma_len, &off, PAGE_SIZE);
- if (unlikely(ret != ibmr->sg_len))
- if (unlikely(ret != ibmr->sg_dma_len)) return ret < 0 ? ret : -EINVAL;
/* Perform a WR for the fast_reg_mr. Each individual page