[PATCH v3 6/8] mm/gup: use a standard migration target allocation callback

[js1304@gmail.com]

From: Joonsoo Kim <iamjoonsoo.kim@lge.com>

There is a well-defined migration target allocation callback.
It's mostly similar with new_non_cma_page() except considering CMA pages.

This patch adds a CMA consideration to the standard migration target
allocation callback and use it on gup.c.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
---
 mm/gup.c      | 57 ++++++++-------------------------------------------------
 mm/internal.h |  1 +
 mm/migrate.c  |  4 +++-
 3 files changed, 12 insertions(+), 50 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 15be281..f6124e3 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1608,56 +1608,15 @@ 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)
+static struct page *alloc_migration_target_non_cma(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 movable
-	 * allocation memory.
-	 */
-	gfp_t gfp_mask = GFP_USER | __GFP_NOWARN;
-
-	if (PageHighMem(page))
-		gfp_mask |= __GFP_HIGHMEM;
-
-#ifdef CONFIG_HUGETLB_PAGE
-	if (PageHuge(page)) {
-		struct hstate *h = page_hstate(page);
-
-		/*
-		 * We don't want to dequeue from the pool because pool pages will
-		 * mostly be from the CMA region.
-		 */
-		return alloc_huge_page_nodemask(h, nid, NULL, gfp_mask, true);
-	}
-#endif
-	if (PageTransHuge(page)) {
-		struct page *thp;
-		/*
-		 * ignore allocation failure warnings
-		 */
-		gfp_t thp_gfpmask = GFP_TRANSHUGE | __GFP_NOWARN;
-
-		/*
-		 * Remove the movable mask so that we don't allocate from
-		 * CMA area again.
-		 */
-		thp_gfpmask &= ~__GFP_MOVABLE;
-		thp = __alloc_pages_node(nid, thp_gfpmask, HPAGE_PMD_ORDER);
-		if (!thp)
-			return NULL;
-		prep_transhuge_page(thp);
-		return thp;
-	}
+	struct migration_target_control mtc = {
+		.nid = page_to_nid(page),
+		.gfp_mask = GFP_USER | __GFP_NOWARN,
+		.skip_cma = true,
+	};
 
-	return __alloc_pages_node(nid, gfp_mask, 0);
+	return alloc_migration_target(page, (unsigned long)&mtc);
 }
 
 static long check_and_migrate_cma_pages(struct task_struct *tsk,
@@ -1719,7 +1678,7 @@ 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,
+		if (migrate_pages(&cma_page_list, alloc_migration_target_non_cma,
 				  NULL, 0, MIGRATE_SYNC, MR_CONTIG_RANGE)) {
 			/*
 			 * some of the pages failed migration. Do get_user_pages
diff --git a/mm/internal.h b/mm/internal.h
index f725aa8..fb7f7fe 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -619,6 +619,7 @@ struct migration_target_control {
 	int nid;		/* preferred node id */
 	nodemask_t *nmask;
 	gfp_t gfp_mask;
+	bool skip_cma;
 };
 
 #endif	/* __MM_INTERNAL_H */
diff --git a/mm/migrate.c b/mm/migrate.c
index 3afff59..7c4cd74 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1550,7 +1550,7 @@ struct page *alloc_migration_target(struct page *page, unsigned long private)
 	if (PageHuge(page)) {
 		return alloc_huge_page_nodemask(
 				page_hstate(compound_head(page)), mtc->nid,
-				mtc->nmask, gfp_mask, false);
+				mtc->nmask, gfp_mask, mtc->skip_cma);
 	}
 
 	if (PageTransHuge(page)) {
@@ -1561,6 +1561,8 @@ struct page *alloc_migration_target(struct page *page, unsigned long private)
 	zidx = zone_idx(page_zone(page));
 	if (is_highmem_idx(zidx) || zidx == ZONE_MOVABLE)
 		gfp_mask |= __GFP_HIGHMEM;
+	if (mtc->skip_cma)
+		gfp_mask &= ~__GFP_MOVABLE;
 
 	new_page = __alloc_pages_nodemask(gfp_mask, order,
 				mtc->nid, mtc->nmask);
-- 
2.7.4