drm/nouveau: uvmm: fix unset region pointer on remap

Transfer the region pointer of a uvma to the new uvma(s) on re-map to
prevent potential shader faults when the re-mapped uvma(s) are unmapped.
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230820222920.2344-1-dakr@redhat.com

drivers/gpu/drm/nouveau/nouveau_uvmm.c

@@ -639,6 +639,7 @@ nouveau_uvmm_sm_prepare(struct nouveau_uvmm *uvmm,
 			struct drm_gpuva *va = r->unmap->va;
 			struct uvmm_map_args remap_args = {
 				.kind = uvma_from_va(va)->kind,
+				.region = uvma_from_va(va)->region,
 			};
 			u64 ustart = va->va.addr;
 			u64 urange = va->va.range;