In-use hugetlb pages can be migrated as any other page (LRU
and Movable), so let alloc_contig_range handle them.

All we need is to succesfully isolate such page.

Signed-off-by: Oscar Salvador <osalvador@suse.de>
---
 include/linux/hugetlb.h |  5 +++--
 mm/compaction.c         | 11 ++++++++++-
 mm/hugetlb.c            |  6 ++++--
 mm/vmscan.c             |  5 +++--
 4 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 72352d718829..8c17d0dbc87c 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h

@@ -505,7 +505,7 @@ struct huge_bootmem_page {
 	struct hstate *hstate;
 };
 
-bool isolate_or_dissolve_huge_page(struct page *page);
+bool isolate_or_dissolve_huge_page(struct page *page, struct list_head *list);
 struct page *alloc_huge_page(struct vm_area_struct *vma,
 				unsigned long addr, int avoid_reserve);
 struct page *alloc_huge_page_nodemask(struct hstate *h, int preferred_nid,

@@ -776,7 +776,8 @@ void set_page_huge_active(struct page *page);
 #else	/* CONFIG_HUGETLB_PAGE */
 struct hstate {};
 
-static inline bool isolate_or_dissolve_huge_page(struct page *page)
+static inline bool isolate_or_dissolve_huge_page(struct page *page,
+						 struct list_head *list)
 {
 	return false;
 }

diff --git a/mm/compaction.c b/mm/compaction.c
index d52506ed9db7..55a41a9228a9 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c

@@ -906,9 +906,17 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 		}
 
 		if (PageHuge(page) && cc->alloc_contig) {
-			if (!isolate_or_dissolve_huge_page(page))
+			if (!isolate_or_dissolve_huge_page(page, &cc->migratepages))
 				goto isolate_fail;
 
+			if (PageHuge(page)) {
+				/*
+				 * Hugepage was succesfully isolated.
+				 */
+				low_pfn += compound_nr(page) - 1;
+				goto isolate_success_no_list;
+			}
+
 			/*
 			 * Ok, the hugepage was dissolved. Now these pages are
 			 * Buddy and cannot be re-allocated because they are

@@ -1053,6 +1061,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 
 isolate_success:
 		list_add(&page->lru, &cc->migratepages);
+isolate_success_no_list:
 		cc->nr_migratepages += compound_nr(page);