[Linaro-mm-sig] Re: [PATCH] iommufd: take dma_resv lock before dma_buf_unpin() in release path

On Tue, May 26, 2026 at 11:10:34AM +0000, Ankit Soni wrote:

dma_buf_unpin() requires the caller to hold the exporter's dma_resv lock:

void dma_buf_unpin(struct dma_buf_attachment *attach) { ... dma_resv_assert_held(dmabuf->resv); ... }

iopt_release_pages() calls dma_buf_unpin() without taking that lock, so every iommufd_ioas_destroy()/iommufd_ioas_unmap() that releases the last reference on a DMABUF-backed iopt_pages triggers a WARN. This was hit while running tools/testing/selftests/iommu/iommufd:

Any idea why this is comming up now? Did I run the tests without some kind of debug option to turn on that assertion maybe?

Jason