diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
index 4082c8f2951dfdace7f73a24d6fe34e9e7f920eb..6fbff516c1c1f047fcb4dee17b87d8263616dc0c 100644
--- a/drivers/gpu/drm/panthor/panthor_device.c
+++ b/drivers/gpu/drm/panthor/panthor_device.c
@@ -390,11 +390,15 @@ int panthor_device_mmap_io(struct panthor_device *ptdev, struct vm_area_struct *
 {
 	u64 offset = (u64)vma->vm_pgoff << PAGE_SHIFT;
 
+	if ((vma->vm_flags & VM_SHARED) == 0)
+		return -EINVAL;
+
 	switch (offset) {
 	case DRM_PANTHOR_USER_FLUSH_ID_MMIO_OFFSET:
 		if (vma->vm_end - vma->vm_start != PAGE_SIZE ||
 		    (vma->vm_flags & (VM_WRITE | VM_EXEC)))
 			return -EINVAL;
+		vm_flags_clear(vma, VM_MAYWRITE);
 
 		break;