diff -u b/core/lib/Drupal/Component/PhpStorage/FileStorage.php b/core/lib/Drupal/Component/PhpStorage/FileStorage.php
--- b/core/lib/Drupal/Component/PhpStorage/FileStorage.php
+++ b/core/lib/Drupal/Component/PhpStorage/FileStorage.php
@@ -76,17 +76,25 @@
    */
   protected function ensureDirectory($directory, $mode = 0777) {
     // If the directory exists already, there's nothing to do.
+    if (is_dir($directory)) {
+      return TRUE;
+    }
     // Otherwise, try to create the directory and ensure to set its permissions,
     // because mkdir() obeys the umask of the current process.
-    $parent = dirname($directory);
-    if (is_dir($directory) || (is_dir($parent) && mkdir($directory) && chmod($directory, $mode))) {
+    if (is_dir($parent = dirname($directory))) {
+      // If the parent directory exists, then the backwards recursion must end,
+      // regardless of whether the subdirectory could be created.
+      if (mkdir($directory)) {
+        // Only try to chmod() if the subdirectory could be created.
+        chmod($directory, $mode);
+      }
       return TRUE;
     }
     // If the directory does not exist and could not be created above, walk the
     // requested directory path back up until an existing directory is hit, and
     // from there, recursively create the sub-directories. If that recursion
     // succeeds, create the final subdirectory.
-    return $this->ensureDirectory($parent, $mode) && mkdir($directory);
+    return $this->ensureDirectory($parent, $mode) && mkdir($directory) && chmod($directory, $mode);
   }
 
   /**