diff --git a/drivers/iommu/iommufd/selftest.c b/drivers/iommu/iommufd/selftest.c
index 56506d5753f1..00b794d74e03 100644
--- a/drivers/iommu/iommufd/selftest.c
+++ b/drivers/iommu/iommufd/selftest.c
@@ -44,8 +44,8 @@ enum {
  * In syzkaller mode the 64 bit IOVA is converted into an nth area and offset
  * value. This has a much smaller randomization space and syzkaller can hit it.
  */
-static unsigned long iommufd_test_syz_conv_iova(struct io_pagetable *iopt,
-						u64 *iova)
+static unsigned long __iommufd_test_syz_conv_iova(struct io_pagetable *iopt,
+						  u64 *iova)
 {
 	struct syz_layout {
 		__u32 nth_area;
@@ -69,6 +69,21 @@ static unsigned long iommufd_test_syz_conv_iova(struct io_pagetable *iopt,
 	return 0;
 }
 
+static unsigned long iommufd_test_syz_conv_iova(struct iommufd_access *access,
+						u64 *iova)
+{
+	unsigned long ret;
+
+	mutex_lock(&access->ioas_lock);
+	if (!access->ioas) {
+		mutex_unlock(&access->ioas_lock);
+		return 0;
+	}
+	ret = __iommufd_test_syz_conv_iova(&access->ioas->iopt, iova);
+	mutex_unlock(&access->ioas_lock);
+	return ret;
+}
+
 void iommufd_test_syz_conv_iova_id(struct iommufd_ucmd *ucmd,
 				   unsigned int ioas_id, u64 *iova, u32 *flags)
 {
@@ -81,7 +96,7 @@ void iommufd_test_syz_conv_iova_id(struct iommufd_ucmd *ucmd,
 	ioas = iommufd_get_ioas(ucmd->ictx, ioas_id);
 	if (IS_ERR(ioas))
 		return;
-	*iova = iommufd_test_syz_conv_iova(&ioas->iopt, iova);
+	*iova = __iommufd_test_syz_conv_iova(&ioas->iopt, iova);
 	iommufd_put_object(&ioas->obj);
 }
 
@@ -852,7 +867,7 @@ static int iommufd_test_access_pages(struct iommufd_ucmd *ucmd,
 	}
 
 	if (flags & MOCK_FLAGS_ACCESS_SYZ)
-		iova = iommufd_test_syz_conv_iova(&staccess->access->ioas->iopt,
+		iova = iommufd_test_syz_conv_iova(staccess->access,
 					&cmd->access_pages.iova);
 
 	npages = (ALIGN(iova + length, PAGE_SIZE) -
@@ -954,8 +969,8 @@ static int iommufd_test_access_rw(struct iommufd_ucmd *ucmd,
 	}
 
 	if (flags & MOCK_FLAGS_ACCESS_SYZ)
-		iova = iommufd_test_syz_conv_iova(&staccess->access->ioas->iopt,
-					&cmd->access_rw.iova);
+		iova = iommufd_test_syz_conv_iova(staccess->access,
+				&cmd->access_rw.iova);
 
 	rc = iommufd_access_rw(staccess->access, iova, tmp, length, flags);
 	if (rc)