It seems it was never used.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
 include/linux/sysctl.h | 2 --
 1 file changed, 2 deletions(-)

diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 61b40ea81f4d..26a38161c28f 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -255,8 +255,6 @@ extern int unaligned_enabled;
 extern int unaligned_dump_stack;
 extern int no_unaligned_warning;
 
-#define SYSCTL_PERM_EMPTY_DIR	(1 << 0)
-
 #else /* CONFIG_SYSCTL */
 
 static inline void register_sysctl_init(const char *path, struct ctl_table *table)

-- 
2.43.0