CVE-2026-74420: drm/gpusvm: Reject VMAs with VM_IO or VM_PFNMAP when creating SVM ranges

In the Linux kernel, the following vulnerability has been resolved:

drm/gpusvm: Reject VMAs with VMIO or VMPFNMAP when creating SVM ranges

VMAs marked with VMIO or VMPFNMAP are not backed by struct page objects, which GPUSVM requires in order to operate correctly. In particular, getpages() relies on hmmrangefault() to resolve struct pages for the target range.

Attempting to create an SVM range on such VMAs results in repeated getpages() failures and can lead to an infinite loop inside a driver’s page‑fault handler. Prevent this by rejecting ranges on VMIO or VMPFNMAP VMAs and returning -EIO.