2 files changed, 7 insertions, 0 deletions

diff --git a/Documentation/kbuild/kconfig-language.txt b/Documentation/kbuild/kconfig-language.txt
index c858f8419eba..c420676c6fe3 100644
--- a/Documentation/kbuild/kconfig-language.txt
+++ b/Documentation/kbuild/kconfig-language.txt
@@ -147,6 +147,7 @@ applicable everywhere (see syntax).
   - "modules"
     This declares the symbol to be used as the MODULES symbol, which
     enables the third modular state for all config symbols.
+    At most one symbol may have the "modules" option set.
 
   - "env"=<value>
     This imports the environment variable into Kconfig. It behaves like
diff --git a/scripts/kconfig/menu.c b/scripts/kconfig/menu.c
index 3a9c67493260..c1d53200c306 100644
--- a/scripts/kconfig/menu.c
+++ b/scripts/kconfig/menu.c
@@ -199,6 +199,12 @@ void menu_add_option(int token, char *arg)
 {
         switch (token) {
         case T_OPT_MODULES:
+                if (modules_sym)
+                        zconf_error("symbol '%s' redefines option 'modules'"
+                                    " already defined by symbol '%s'",
+                                    current_entry->sym->name,
+                                    modules_sym->name
+                                    );
                 modules_sym = current_entry->sym;
                 break;
         case T_OPT_DEFCONFIG_LIST: