diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -1372,10 +1372,10 @@ class localrepository(object):
                         if not force:
                             raise util.Abort(
                                 _("commit with new subrepo %s excluded") % s)
-                    if wctx.sub(s).dirty(True):
+                    dirtyreason = wctx.sub(s).dirtyreason(True)
+                    if dirtyreason:
                         if not self.ui.configbool('ui', 'commitsubrepos'):
-                            raise util.Abort(
-                                _("uncommitted changes in subrepo %s") % s,
+                            raise util.Abort(dirtyreason,
                                 hint=_("use --subrepos for recursive commit"))
                         subs.append(s)
                         commitsubs.add(s)
diff --git a/mercurial/subrepo.py b/mercurial/subrepo.py
--- a/mercurial/subrepo.py
+++ b/mercurial/subrepo.py
@@ -390,6 +390,18 @@ class abstractsubrepo(object):
         """
         raise NotImplementedError
 
+    def dirtyreason(self, ignoreupdate=False):
+        """return reason string if it is ``dirty()``
+
+        Returned string should have enough information for the message
+        of exception.
+
+        This returns None, otherwise.
+        """
+        if self.dirty(ignoreupdate=ignoreupdate):
+            return _("uncommitted changes in subrepository '%s'"
+                     ) % subrelpath(self)
+
     def basestate(self):
         """current working directory base state, disregarding .hgsubstate
         state and working directory modifications"""
diff --git a/tests/test-largefiles-misc.t b/tests/test-largefiles-misc.t
--- a/tests/test-largefiles-misc.t
+++ b/tests/test-largefiles-misc.t
@@ -248,7 +248,7 @@ verify that large files in subrepos hand
   commit: 1 subrepos
   update: (current)
   $ hg ci -m "this commit should fail without -S"
-  abort: uncommitted changes in subrepo subrepo
+  abort: uncommitted changes in subrepository 'subrepo'
   (use --subrepos for recursive commit)
   [255]
 
diff --git a/tests/test-subrepo-recursion.t b/tests/test-subrepo-recursion.t
--- a/tests/test-subrepo-recursion.t
+++ b/tests/test-subrepo-recursion.t
@@ -59,7 +59,7 @@ Test recursive diff without committing a
 Commits:
 
   $ hg commit -m fails
-  abort: uncommitted changes in subrepo foo
+  abort: uncommitted changes in subrepository 'foo'
   (use --subrepos for recursive commit)
   [255]
 
diff --git a/tests/test-subrepo.t b/tests/test-subrepo.t
--- a/tests/test-subrepo.t
+++ b/tests/test-subrepo.t
@@ -146,7 +146,7 @@ leave sub dirty (and check ui.commitsubr
 
   $ echo c > s/a
   $ hg --config ui.commitsubrepos=no ci -m4
-  abort: uncommitted changes in subrepo s
+  abort: uncommitted changes in subrepository 's'
   (use --subrepos for recursive commit)
   [255]
   $ hg id