[PATCH v6 12/16] mm/hugetlb: Set the PageHWPoison to the raw error page

[Muchun Song]

Because we reuse the first tail vmemmap page frame and remap it
with read-only, we cannot set the PageHWPosion on a tail page.
So we can use the head[4].mapping to record the real error page
index and set the raw error page PageHWPoison later.

Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
---
 mm/hugetlb.c         | 11 +++--------
 mm/hugetlb_vmemmap.h | 39 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 8 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 3fafa39fcac6..ade20954eb81 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1383,6 +1383,7 @@ static void __free_hugepage(struct hstate *h, struct page *page)
 	int i;
 
 	alloc_huge_page_vmemmap(h, page);
+	subpage_hwpoison_deliver(page);
 
 	for (i = 0; i < pages_per_huge_page(h); i++) {
 		page[i].flags &= ~(1 << PG_locked | 1 << PG_error |
@@ -1930,14 +1931,8 @@ int dissolve_free_huge_page(struct page *page)
 		int nid = page_to_nid(head);
 		if (h->free_huge_pages - h->resv_huge_pages == 0)
 			goto out;
-		/*
-		 * Move PageHWPoison flag from head page to the raw error page,
-		 * which makes any subpages rather than the error page reusable.
-		 */
-		if (PageHWPoison(head) && page != head) {
-			SetPageHWPoison(page);
-			ClearPageHWPoison(head);
-		}
+
+		set_subpage_hwpoison(head, page);
 		list_del(&head->lru);
 		h->free_huge_pages--;
 		h->free_huge_pages_node[nid]--;
diff --git a/mm/hugetlb_vmemmap.h b/mm/hugetlb_vmemmap.h
index 7887095488f4..4bb35d87ae10 100644
--- a/mm/hugetlb_vmemmap.h
+++ b/mm/hugetlb_vmemmap.h
@@ -15,6 +15,29 @@ void __init hugetlb_vmemmap_init(struct hstate *h);
 void alloc_huge_page_vmemmap(struct hstate *h, struct page *head);
 void free_huge_page_vmemmap(struct hstate *h, struct page *head);
 
+static inline void subpage_hwpoison_deliver(struct page *head)
+{
+	struct page *page = head;
+
+	if (PageHWPoison(head))
+		page = head + page_private(head + 4);
+
+	/*
+	 * Move PageHWPoison flag from head page to the raw error page,
+	 * which makes any subpages rather than the error page reusable.
+	 */
+	if (page != head) {
+		SetPageHWPoison(page);
+		ClearPageHWPoison(head);
+	}
+}
+
+static inline void set_subpage_hwpoison(struct page *head, struct page *page)
+{
+	if (PageHWPoison(head))
+		set_page_private(head + 4, page - head);
+}
+
 static inline unsigned int free_vmemmap_pages_per_hpage(struct hstate *h)
 {
 	return h->nr_free_vmemmap_pages;
@@ -32,6 +55,22 @@ static inline void free_huge_page_vmemmap(struct hstate *h, struct page *head)
 {
 }
 
+static inline void subpage_hwpoison_deliver(struct page *head)
+{
+}
+
+static inline void set_subpage_hwpoison(struct page *head, struct page *page)
+{
+	/*
+	 * Move PageHWPoison flag from head page to the raw error page,
+	 * which makes any subpages rather than the error page reusable.
+	 */
+	if (PageHWPoison(head) && page != head) {
+		SetPageHWPoison(page);
+		ClearPageHWPoison(head);
+	}
+}
+
 static inline unsigned int free_vmemmap_pages_per_hpage(struct hstate *h)
 {
 	return 0;
-- 
2.11.0