[PATCH 07/12] hugetlb: perform vmemmap restoration on a list of pages

[Mike Kravetz]

When removing hugetlb pages from the pool, we first create a list
of removed pages and then free those pages back to low level allocators.
Part of the 'freeing process' is to restore vmemmap for all base pages
if necessary.  Pass this list of pages to a new routine
hugetlb_vmemmap_restore_folios() so that vmemmap restoration can be
performed in bulk.

Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
---
 mm/hugetlb.c         | 3 +++
 mm/hugetlb_vmemmap.c | 8 ++++++++
 mm/hugetlb_vmemmap.h | 6 ++++++
 3 files changed, 17 insertions(+)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 3133dbd89696..1bde5e234d5c 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1833,6 +1833,9 @@ static void update_and_free_pages_bulk(struct hstate *h, struct list_head *list)
 {
 	struct folio *folio, *t_folio;
 
+	/* First restore vmemmap for all pages on list. */
+	hugetlb_vmemmap_restore_folios(h, list);
+
 	list_for_each_entry_safe(folio, t_folio, list, lru) {
 		update_and_free_hugetlb_folio(h, folio, false);
 		cond_resched();
diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
index 147018a504a6..d5e6b6c76dce 100644
--- a/mm/hugetlb_vmemmap.c
+++ b/mm/hugetlb_vmemmap.c
@@ -479,6 +479,14 @@ int hugetlb_vmemmap_restore(const struct hstate *h, struct page *head)
 	return ret;
 }
 
+void hugetlb_vmemmap_restore_folios(const struct hstate *h, struct list_head *folio_list)
+{
+	struct folio *folio;
+
+	list_for_each_entry(folio, folio_list, lru)
+		hugetlb_vmemmap_restore(h, &folio->page);
+}
+
 /* Return true iff a HugeTLB whose vmemmap should and can be optimized. */
 static bool vmemmap_should_optimize(const struct hstate *h, const struct page *head)
 {
diff --git a/mm/hugetlb_vmemmap.h b/mm/hugetlb_vmemmap.h
index 036494e040ca..b7074672ceb2 100644
--- a/mm/hugetlb_vmemmap.h
+++ b/mm/hugetlb_vmemmap.h
@@ -12,6 +12,7 @@
 
 #ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP
 int hugetlb_vmemmap_restore(const struct hstate *h, struct page *head);
+void hugetlb_vmemmap_restore_folios(const struct hstate *h, struct list_head *folio_list);
 void hugetlb_vmemmap_optimize(const struct hstate *h, struct page *head);
 void hugetlb_vmemmap_optimize_folios(struct hstate *h, struct list_head *folio_list);
 
@@ -44,6 +45,11 @@ static inline int hugetlb_vmemmap_restore(const struct hstate *h, struct page *h
 	return 0;
 }
 
+static inline void hugetlb_vmemmap_restore_folios(const struct hstate *h, struct list_head *folio_list)
+{
+	return 0;
+}
+
 static inline void hugetlb_vmemmap_optimize(const struct hstate *h, struct page *head)
 {
 }
-- 
2.41.0