Re: [PATCH v2 7/8] RDMA/umem: Tell DMA mapping that UMEM requires coherency

Jason Gunthorpe
2026-03-12T12:22:24Z

On Wed, Mar 11, 2026 at 09:08:50PM +0200, Leon Romanovsky wrote:
> From: Leon Romanovsky <leonro@nvidia.com>
>
> The RDMA subsystem exposes DMA regions through the verbs interface, which
> assumes a coherent system. Use the DMA_ATTR_REQUIRE_COHERENCE attribute to
> ensure coherency and avoid taking the SWIOTLB path.
>
> In addition, a given region may be exported multiple times, which will trigger
> warnings about cacheline overlaps. These warnings are suppressed when using
> the new attribute.

> Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
> ---
> drivers/infiniband/core/umem.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason