mm/migrate: move migration helper from .h to .c

It's not performance sensitive function.  Move it to .c.  This is a
preparation step for future change.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Roman Gushchin <guro@fb.com>
Link: http://lkml.kernel.org/r/1594622517-20681-3-git-send-email-iamjoonsoo.kim@lge.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/migrate.h

@@ -31,34 +31,6 @@ enum migrate_reason {
 /* In mm/debug.c; also keep sync with include/trace/events/migrate.h */
 extern const char *migrate_reason_names[MR_TYPES];
 
-static inline struct page *new_page_nodemask(struct page *page,
-				int preferred_nid, nodemask_t *nodemask)
-{
-	gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL;
-	unsigned int order = 0;
-	struct page *new_page = NULL;
-
-	if (PageHuge(page))
-		return alloc_huge_page_nodemask(page_hstate(compound_head(page)),
-				preferred_nid, nodemask);
-
-	if (PageTransHuge(page)) {
-		gfp_mask |= GFP_TRANSHUGE;
-		order = HPAGE_PMD_ORDER;
-	}
-
-	if (PageHighMem(page) || (zone_idx(page_zone(page)) == ZONE_MOVABLE))
-		gfp_mask |= __GFP_HIGHMEM;
-
-	new_page = __alloc_pages_nodemask(gfp_mask, order,
-				preferred_nid, nodemask);
-
-	if (new_page && PageTransHuge(new_page))
-		prep_transhuge_page(new_page);
-
-	return new_page;
-}
-
 #ifdef CONFIG_MIGRATION
 
 extern void putback_movable_pages(struct list_head *l);
@@ -67,6 +39,8 @@ extern int migrate_page(struct address_space *mapping,
 			enum migrate_mode mode);
 extern int migrate_pages(struct list_head *l, new_page_t new, free_page_t free,
 		unsigned long private, enum migrate_mode mode, int reason);
+extern struct page *new_page_nodemask(struct page *page,
+		int preferred_nid, nodemask_t *nodemask);
 extern int isolate_movable_page(struct page *page, isolate_mode_t mode);
 extern void putback_movable_page(struct page *page);
 
@@ -85,6 +59,9 @@ static inline int migrate_pages(struct list_head *l, new_page_t new,
 		free_page_t free, unsigned long private, enum migrate_mode mode,
 		int reason)
 	{ return -ENOSYS; }
+static inline struct page *new_page_nodemask(struct page *page,
+		int preferred_nid, nodemask_t *nodemask)
+	{ return NULL; }
 static inline int isolate_movable_page(struct page *page, isolate_mode_t mode)
 	{ return -EBUSY; }
 

mm/migrate.c

@@ -1538,6 +1538,35 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
 	return rc;
 }
 
+struct page *new_page_nodemask(struct page *page,
+				int preferred_nid, nodemask_t *nodemask)
+{
+	gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL;
+	unsigned int order = 0;
+	struct page *new_page = NULL;
+
+	if (PageHuge(page))
+		return alloc_huge_page_nodemask(
+				page_hstate(compound_head(page)),
+				preferred_nid, nodemask);
+
+	if (PageTransHuge(page)) {
+		gfp_mask |= GFP_TRANSHUGE;
+		order = HPAGE_PMD_ORDER;
+	}
+
+	if (PageHighMem(page) || (zone_idx(page_zone(page)) == ZONE_MOVABLE))
+		gfp_mask |= __GFP_HIGHMEM;
+
+	new_page = __alloc_pages_nodemask(gfp_mask, order,
+				preferred_nid, nodemask);
+
+	if (new_page && PageTransHuge(new_page))
+		prep_transhuge_page(new_page);
+
+	return new_page;
+}
+
 #ifdef CONFIG_NUMA
 
 static int store_status(int __user *status, int start, int value, int nr)