On Thu, Sep 16, 2021 at 05:40:59PM -0600, Logan Gunthorpe wrote:

+int pci_mmap_p2pmem(struct pci_dev *pdev, struct vm_area_struct *vma)
+{
+	struct pci_p2pdma_map *pmap;
+	struct pci_p2pdma *p2pdma;
+	int ret;
+
+	/* prevent private mappings from being established */
+	if ((vma->vm_flags & VM_MAYSHARE) != VM_MAYSHARE) {
+		pci_info_ratelimited(pdev,
+				     "%s: fail, attempted private mapping\n",
+				     current->comm);
+		return -EINVAL;
+	}
+
+	pmap = pci_p2pdma_map_alloc(pdev, vma->vm_end - vma->vm_start);
+	if (!pmap)
+		return -ENOMEM;
+
+	rcu_read_lock();
+	p2pdma = rcu_dereference(pdev->p2pdma);
+	if (!p2pdma) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	ret = simple_pin_fs(&pci_p2pdma_fs_type, &pci_p2pdma_fs_mnt,
+			    &pci_p2pdma_fs_cnt);
+	if (ret)
+		goto out;
+
+	ihold(p2pdma->inode);
+	pmap->inode = p2pdma->inode;
+	rcu_read_unlock();
+
+	vma->vm_flags |= VM_MIXEDMAP;

Why is this a VM_MIXEDMAP? Everything fault sticks in here has a
struct page, right?

Jason