mm/hmm: fix header file if/else/endif maze, again

The last fix was still wrong, as we need the inline dummy functions also
for the case that CONFIG_HMM is enabled but CONFIG_HMM_MIRROR is not:

  kernel/fork.o: In function `__mmdrop':
  fork.c:(.text+0x14f6): undefined reference to `hmm_mm_destroy'

This adds back the second copy of the dummy functions, hopefully
this time in the right place.

Link: http://lkml.kernel.org/r/20180404110236.804484-1-arnd@arndb.de
Fixes: 8900d06a277a ("mm/hmm: fix header file if/else/endif maze")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/hmm.h

@@ -376,8 +376,18 @@ bool hmm_vma_range_done(struct hmm_range *range);
  * See the function description in mm/hmm.c for further documentation.
  */
 int hmm_vma_fault(struct hmm_range *range, bool block);
-#endif /* IS_ENABLED(CONFIG_HMM_MIRROR) */
 
+/* Below are for HMM internal use only! Not to be used by device driver! */
+void hmm_mm_destroy(struct mm_struct *mm);
+
+static inline void hmm_mm_init(struct mm_struct *mm)
+{
+	mm->hmm = NULL;
+}
+#else /* IS_ENABLED(CONFIG_HMM_MIRROR) */
+static inline void hmm_mm_destroy(struct mm_struct *mm) {}
+static inline void hmm_mm_init(struct mm_struct *mm) {}
+#endif /* IS_ENABLED(CONFIG_HMM_MIRROR) */
 
 #if IS_ENABLED(CONFIG_DEVICE_PRIVATE) ||  IS_ENABLED(CONFIG_DEVICE_PUBLIC)
 struct hmm_devmem;
@@ -550,16 +560,9 @@ struct hmm_device {
 struct hmm_device *hmm_device_new(void *drvdata);
 void hmm_device_put(struct hmm_device *hmm_device);
 #endif /* CONFIG_DEVICE_PRIVATE || CONFIG_DEVICE_PUBLIC */
-
-/* Below are for HMM internal use only! Not to be used by device driver! */
-void hmm_mm_destroy(struct mm_struct *mm);
-
-static inline void hmm_mm_init(struct mm_struct *mm)
-{
-	mm->hmm = NULL;
-}
 #else /* IS_ENABLED(CONFIG_HMM) */
 static inline void hmm_mm_destroy(struct mm_struct *mm) {}
 static inline void hmm_mm_init(struct mm_struct *mm) {}
 #endif /* IS_ENABLED(CONFIG_HMM) */
+
 #endif /* LINUX_HMM_H */