mm/gup: use a standard migration target allocation callback

There is a well-defined migration target allocation callback. Use it.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Roman Gushchin <guro@fb.com>
Link: http://lkml.kernel.org/r/1596180906-8442-3-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Author: JoonsooKim

mm/gup.c

@@ -1609,52 +1609,6 @@ static bool check_dax_vmas(struct vm_area_struct **vmas, long nr_pages)
 }
 
 #ifdef CONFIG_CMA
-static struct page *new_non_cma_page(struct page *page, unsigned long private)
-{
-	/*
-	 * We want to make sure we allocate the new page from the same node
-	 * as the source page.
-	 */
-	int nid = page_to_nid(page);
-	/*
-	 * Trying to allocate a page for migration. Ignore allocation
-	 * failure warnings. We don't force __GFP_THISNODE here because
-	 * this node here is the node where we have CMA reservation and
-	 * in some case these nodes will have really less non CMA
-	 * allocation memory.
-	 *
-	 * Note that CMA region is prohibited by allocation scope.
-	 */
-	gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_NOWARN;
-
-	if (PageHighMem(page))
-		gfp_mask |= __GFP_HIGHMEM;
-
-#ifdef CONFIG_HUGETLB_PAGE
-	if (PageHuge(page)) {
-		struct hstate *h = page_hstate(page);
-
-		gfp_mask = htlb_modify_alloc_mask(h, gfp_mask);
-		return alloc_huge_page_nodemask(h, nid, NULL, gfp_mask);
-	}
-#endif
-	if (PageTransHuge(page)) {
-		struct page *thp;
-		/*
-		 * ignore allocation failure warnings
-		 */
-		gfp_t thp_gfpmask = GFP_TRANSHUGE | __GFP_NOWARN;
-
-		thp = __alloc_pages_node(nid, thp_gfpmask, HPAGE_PMD_ORDER);
-		if (!thp)
-			return NULL;
-		prep_transhuge_page(thp);
-		return thp;
-	}
-
-	return __alloc_pages_node(nid, gfp_mask, 0);
-}
-
 static long check_and_migrate_cma_pages(struct task_struct *tsk,
 					struct mm_struct *mm,
 					unsigned long start,
@@ -1669,6 +1623,10 @@ static long check_and_migrate_cma_pages(struct task_struct *tsk,
 	bool migrate_allow = true;
 	LIST_HEAD(cma_page_list);
 	long ret = nr_pages;
+	struct migration_target_control mtc = {
+		.nid = NUMA_NO_NODE,
+		.gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_NOWARN,
+	};
 
 check_again:
 	for (i = 0; i < nr_pages;) {
@@ -1714,8 +1672,8 @@ static long check_and_migrate_cma_pages(struct task_struct *tsk,
 		for (i = 0; i < nr_pages; i++)
 			put_page(pages[i]);
 
-		if (migrate_pages(&cma_page_list, new_non_cma_page,
-				  NULL, 0, MIGRATE_SYNC, MR_CONTIG_RANGE)) {
+		if (migrate_pages(&cma_page_list, alloc_migration_target, NULL,
+			(unsigned long)&mtc, MIGRATE_SYNC, MR_CONTIG_RANGE)) {
 			/*
 			 * some of the pages failed migration. Do get_user_pages
 			 * without migration.