These functions are introduced in hugetlb.c so the private
hugetlb_lock can be accessed.

These functions will be used in splitting and merging pages in a later
patch.

Signed-off-by: Ackerley Tng <ackerleytng@google.com>
Co-developed-by: Vishal Annapurve <vannapurve@google.com>
Signed-off-by: Vishal Annapurve <vannapurve@google.com>

Change-Id: I42f8feda40cbd28e5fd02e54fa58145d847a220e
---
 include/linux/hugetlb.h |  2 ++
 mm/hugetlb.c            | 22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index e6b90e72d46d..e432ccfe3e63 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -156,6 +156,8 @@ bool hugetlb_reserve_pages(struct inode *inode, long from, long to,
 						vm_flags_t vm_flags);
 long hugetlb_unreserve_pages(struct inode *inode, long start, long end,
 						long freed);
+void hugetlb_folio_list_add(struct folio *folio, struct list_head *list);
+void hugetlb_folio_list_del(struct folio *folio);
 bool folio_isolate_hugetlb(struct folio *folio, struct list_head *list);
 int get_hwpoison_hugetlb_folio(struct folio *folio, bool *hugetlb, bool unpoison);
 int get_huge_page_for_hwpoison(unsigned long pfn, int flags,
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 816f257680be..6e326c09c505 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -7473,6 +7473,28 @@ long hugetlb_unreserve_pages(struct inode *inode, long start, long end,
 	return 0;
 }
 
+void hugetlb_folio_list_add(struct folio *folio, struct list_head *list)
+{
+	/*
+	 * hstate's hugepage_activelist is guarded by hugetlb_lock, hence hold
+	 * hugetlb_lock while modifying folio-> lru.
+	 */
+	spin_lock_irq(&hugetlb_lock);
+	list_add(&folio->lru, list);
+	spin_unlock_irq(&hugetlb_lock);
+}
+
+void hugetlb_folio_list_del(struct folio *folio)
+{
+	/*
+	 * hstate's hugepage_activelist is guarded by hugetlb_lock, hence hold
+	 * hugetlb_lock while modifying folio-> lru.
+	 */
+	spin_lock_irq(&hugetlb_lock);
+	list_del(&folio->lru);
+	spin_unlock_irq(&hugetlb_lock);
+}
+
 #ifdef CONFIG_HUGETLB_PMD_PAGE_TABLE_SHARING
 static unsigned long page_table_shareable(struct vm_area_struct *svma,
 				struct vm_area_struct *vma,
-- 
2.49.0.1045.g170613ef41-goog