[PATCH v2 12/12] mm: memory_hotplug: memory hotremove supports thp migration

[Naoya Horiguchi]

This patch enables thp migration for memory hotremove.

Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
---
ChangeLog v1->v2:
- base code switched from alloc_migrate_target to new_node_page()
---
 mm/memory_hotplug.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git v4.9-rc2-mmotm-2016-10-27-18-27/mm/memory_hotplug.c v4.9-rc2-mmotm-2016-10-27-18-27_patched/mm/memory_hotplug.c
index b18dab40..a9c3fe1 100644
--- v4.9-rc2-mmotm-2016-10-27-18-27/mm/memory_hotplug.c
+++ v4.9-rc2-mmotm-2016-10-27-18-27_patched/mm/memory_hotplug.c
@@ -1543,6 +1543,7 @@ static struct page *new_node_page(struct page *page, unsigned long private,
 	int nid = page_to_nid(page);
 	nodemask_t nmask = node_states[N_MEMORY];
 	struct page *new_page = NULL;
+	unsigned int order = 0;
 
 	/*
 	 * TODO: allocate a destination hugepage from a nearest neighbor node,
@@ -1553,6 +1554,11 @@ static struct page *new_node_page(struct page *page, unsigned long private,
 		return alloc_huge_page_node(page_hstate(compound_head(page)),
 					next_node_in(nid, nmask));
 
+	if (thp_migration_supported() && PageTransHuge(page)) {
+		order = HPAGE_PMD_ORDER;
+		gfp_mask |= GFP_TRANSHUGE;
+	}
+
 	node_clear(nid, nmask);
 
 	if (PageHighMem(page)
@@ -1560,12 +1566,15 @@ static struct page *new_node_page(struct page *page, unsigned long private,
 		gfp_mask |= __GFP_HIGHMEM;
 
 	if (!nodes_empty(nmask))
-		new_page = __alloc_pages_nodemask(gfp_mask, 0,
+		new_page = __alloc_pages_nodemask(gfp_mask, order,
 					node_zonelist(nid, gfp_mask), &nmask);
 	if (!new_page)
-		new_page = __alloc_pages(gfp_mask, 0,
+		new_page = __alloc_pages(gfp_mask, order,
 					node_zonelist(nid, gfp_mask));
 
+	if (new_page && order == HPAGE_PMD_ORDER)
+		prep_transhuge_page(new_page);
+
 	return new_page;
 }
 
@@ -1595,7 +1604,9 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
 			if (isolate_huge_page(page, &source))
 				move_pages -= 1 << compound_order(head);
 			continue;
-		}
+		} else if (thp_migration_supported() && PageTransHuge(page))
+			pfn = page_to_pfn(compound_head(page))
+				+ HPAGE_PMD_NR - 1;
 
 		if (!get_page_unless_zero(page))
 			continue;
-- 
2.7.0