_key is not reserved name and we should avoid using that. It seems that
it was simple typo when pkey_* was implemented.
+2018-02-07 Igor Gnatenko <ignatenko@redhat.com>
+
+ [BZ #22797]
+ * sysdeps/unix/sysv/linux/bits/mman-shared.h (pkey_get): Add
+ missing second underscore to parameter name.
+
2018-02-06 Joseph Myers <joseph@codesourcery.com>
[BZ #14508]
/* Return the access rights for the current thread for KEY, which must
have been allocated using pkey_alloc. */
-int pkey_get (int _key) __THROW;
+int pkey_get (int __key) __THROW;
/* Free an allocated protection key, which must have been allocated
using pkey_alloc. */