mm: numa: Add THP migration for the NUMA working set scanning fault case build fix

Commit "Add THP migration for the NUMA working set scanning fault case"
breaks the build because HPAGE_PMD_SHIFT and HPAGE_PMD_MASK defined to
explode without CONFIG_TRANSPARENT_HUGEPAGE:

mm/migrate.c: In function 'migrate_misplaced_transhuge_page_put':
mm/migrate.c:1549: error: call to '__build_bug_failed' declared with attribute error: BUILD_BUG failed
mm/migrate.c:1564: error: call to '__build_bug_failed' declared with attribute error: BUILD_BUG failed
mm/migrate.c:1566: error: call to '__build_bug_failed' declared with attribute error: BUILD_BUG failed
mm/migrate.c:1573: error: call to '__build_bug_failed' declared with attribute error: BUILD_BUG failed
mm/migrate.c:1606: error: call to '__build_bug_failed' declared with attribute error: BUILD_BUG failed
mm/migrate.c:1648: error: call to '__build_bug_failed' declared with attribute error: BUILD_BUG failed

CONFIG_NUMA_BALANCING allows compilation without enabling transparent
hugepages, so define the dummy function for such a configuration and only
define migrate_misplaced_transhuge_page_put() when transparent hugepages
are enabled.
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>

include/linux/migrate.h

@@ -79,12 +79,6 @@ static inline int migrate_huge_page_move_mapping(struct address_space *mapping,
 extern int migrate_misplaced_page(struct page *page, int node);
 extern int migrate_misplaced_page(struct page *page, int node);
 extern bool migrate_ratelimited(int node);
-extern int migrate_misplaced_transhuge_page(struct mm_struct *mm,
-			struct vm_area_struct *vma,
-			pmd_t *pmd, pmd_t entry,
-			unsigned long address,
-			struct page *page, int node);
-
 #else
 static inline int migrate_misplaced_page(struct page *page, int node)
 {
@@ -94,7 +88,15 @@ static inline bool migrate_ratelimited(int node)
 {
 	return false;
 }
+#endif /* CONFIG_NUMA_BALANCING */
 
+#if defined(CONFIG_NUMA_BALANCING) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
+extern int migrate_misplaced_transhuge_page(struct mm_struct *mm,
+			struct vm_area_struct *vma,
+			pmd_t *pmd, pmd_t entry,
+			unsigned long address,
+			struct page *page, int node);
+#else
 static inline int migrate_misplaced_transhuge_page(struct mm_struct *mm,
 			struct vm_area_struct *vma,
 			pmd_t *pmd, pmd_t entry,
@@ -103,6 +105,6 @@ static inline int migrate_misplaced_transhuge_page(struct mm_struct *mm,
 {
 	return -EAGAIN;
 }
-#endif /* CONFIG_NUMA_BALANCING */
+#endif /* CONFIG_NUMA_BALANCING && CONFIG_TRANSPARENT_HUGEPAGE*/
 
 #endif /* _LINUX_MIGRATE_H */

mm/migrate.c

@@ -1602,7 +1602,9 @@ int migrate_misplaced_page(struct page *page, int node)
 out:
 	return isolated;
 }
+#endif /* CONFIG_NUMA_BALANCING */
 
+#if defined(CONFIG_NUMA_BALANCING) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
 int migrate_misplaced_transhuge_page(struct mm_struct *mm,
 				struct vm_area_struct *vma,
 				pmd_t *pmd, pmd_t entry,