[PATCH 1/8] migrate: make core migration code aware of hugepage

[Naoya Horiguchi]

Before enabling each user of page migration to support hugepage,
this patch enables the list of pages for migration to link not only
LRU pages, but also hugepages. As a result, putback_movable_pages()
and migrate_pages() can handle both of LRU pages and hugepages.

ChangeLog v3:
 - revert introducing migrate_movable_pages
 - add isolate_huge_page

ChangeLog v2:
 - move code removing VM_HUGETLB from vma_migratable check into a
   separate patch
 - hold hugetlb_lock in putback_active_hugepage
 - update comment near the definition of hugetlb_lock

Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
---
 include/linux/hugetlb.h |  6 ++++++
 mm/hugetlb.c            | 32 +++++++++++++++++++++++++++++++-
 mm/migrate.c            | 10 +++++++++-
 3 files changed, 46 insertions(+), 2 deletions(-)

diff --git v3.11-rc1.orig/include/linux/hugetlb.h v3.11-rc1/include/linux/hugetlb.h
index c2b1801..0b7a9e7 100644
--- v3.11-rc1.orig/include/linux/hugetlb.h
+++ v3.11-rc1/include/linux/hugetlb.h
@@ -66,6 +66,9 @@ int hugetlb_reserve_pages(struct inode *inode, long from, long to,
 						vm_flags_t vm_flags);
 void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed);
 int dequeue_hwpoisoned_huge_page(struct page *page);
+bool isolate_huge_page(struct page *page, struct list_head *l);
+void putback_active_hugepage(struct page *page);
+void putback_active_hugepages(struct list_head *l);
 void copy_huge_page(struct page *dst, struct page *src);
 
 #ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
@@ -134,6 +137,9 @@ static inline int dequeue_hwpoisoned_huge_page(struct page *page)
 	return 0;
 }
 
+#define isolate_huge_page(p, l) false
+#define putback_active_hugepage(p)
+#define putback_active_hugepages(l)
 static inline void copy_huge_page(struct page *dst, struct page *src)
 {
 }
diff --git v3.11-rc1.orig/mm/hugetlb.c v3.11-rc1/mm/hugetlb.c
index 83aff0a..4c48a70 100644
--- v3.11-rc1.orig/mm/hugetlb.c
+++ v3.11-rc1/mm/hugetlb.c
@@ -48,7 +48,8 @@ static unsigned long __initdata default_hstate_max_huge_pages;
 static unsigned long __initdata default_hstate_size;
 
 /*
- * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
+ * Protects updates to hugepage_freelists, hugepage_activelist, nr_huge_pages,
+ * free_huge_pages, and surplus_huge_pages.
  */
 DEFINE_SPINLOCK(hugetlb_lock);
 
@@ -3431,3 +3432,32 @@ int dequeue_hwpoisoned_huge_page(struct page *hpage)
 	return ret;
 }
 #endif
+
+bool isolate_huge_page(struct page *page, struct list_head *l)
+{
+	VM_BUG_ON(!PageHead(page));
+	if (!get_page_unless_zero(page))
+		return false;
+	spin_lock(&hugetlb_lock);
+	list_move_tail(&page->lru, l);
+	spin_unlock(&hugetlb_lock);
+	return true;
+}
+
+void putback_active_hugepage(struct page *page)
+{
+	VM_BUG_ON(!PageHead(page));
+	spin_lock(&hugetlb_lock);
+	list_move_tail(&page->lru, &(page_hstate(page))->hugepage_activelist);
+	spin_unlock(&hugetlb_lock);
+	put_page(page);
+}
+
+void putback_active_hugepages(struct list_head *l)
+{
+	struct page *page;
+	struct page *page2;
+
+	list_for_each_entry_safe(page, page2, l, lru)
+		putback_active_hugepage(page);
+}
diff --git v3.11-rc1.orig/mm/migrate.c v3.11-rc1/mm/migrate.c
index 6f0c244..b44a067 100644
--- v3.11-rc1.orig/mm/migrate.c
+++ v3.11-rc1/mm/migrate.c
@@ -100,6 +100,10 @@ void putback_movable_pages(struct list_head *l)
 	struct page *page2;
 
 	list_for_each_entry_safe(page, page2, l, lru) {
+		if (unlikely(PageHuge(page))) {
+			putback_active_hugepage(page);
+			continue;
+		}
 		list_del(&page->lru);
 		dec_zone_page_state(page, NR_ISOLATED_ANON +
 				page_is_file_cache(page));
@@ -1025,7 +1029,11 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
 		list_for_each_entry_safe(page, page2, from, lru) {
 			cond_resched();
 
-			rc = unmap_and_move(get_new_page, private,
+			if (PageHuge(page))
+				rc = unmap_and_move_huge_page(get_new_page,
+						private, page, pass > 2, mode);
+			else
+				rc = unmap_and_move(get_new_page, private,
 						page, pass > 2, mode);
 
 			switch(rc) {
-- 
1.8.3.1

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