Enabling the kernel debug configuration CONFIG_DMA_API_DEBUG_SG can trigger a spurious DMA-API warning when a user‑mode DMA buffer (udmabuf) is imported by a DRM driver such as amdgpu. The warning reports a cacheline tracking EEXIST error caused by two active mappings of the same pages that share a cacheline boundary. The underlying kernel code performs redundant CPU cache maintenance, and the diagnostic warning is harmless; it merely obscures log output during development or debugging.

Any Linux kernel build that has CONFIG_DMA_API_DEBUG_SG enabled and uses drivers that map udmabufs, notably amdgpu and other DRM drivers, will exhibit this warning in kernel versions prior to the fix commit. The issue affects all Linux Kernel revisions that contain the udmabuf implementation without the recently added DMA_ATTR_SKIP_CPU_SYNC flag.

The vulnerability is not listed in the CISA KEV catalog and no exploit code exists. EPSS data is unavailable. Because the warning does not provide unauthorized access or data exposure, the risk is low and limited to noisy log entries. No known attacker can leverage this to compromise the system.