+
+bool isolate_huge_page(struct page *page, struct list_head *list)
+{
+ VM_BUG_ON(!PageHead(page));
+ if (!get_page_unless_zero(page))
+ return false;
+ spin_lock(&hugetlb_lock);
+ list_move_tail(&page->lru, list);
+ 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);
+}
+
+bool is_hugepage_active(struct page *page)
+{
+ VM_BUG_ON(!PageHuge(page));
+ /*
+ * This function can be called for a tail page because the caller,
+ * scan_movable_pages, scans through a given pfn-range which typically
+ * covers one memory block. In systems using gigantic hugepage (1GB
+ * for x86_64,) a hugepage is larger than a memory block, and we don't
+ * support migrating such large hugepages for now, so return false
+ * when called for tail pages.
+ */
+ if (PageTail(page))
+ return false;
+ /*
+ * Refcount of a hwpoisoned hugepages is 1, but they are not active,
+ * so we should return false for them.
+ */
+ if (unlikely(PageHWPoison(page)))
+ return false;
+ return page_count(page) > 0;
+}