[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 <songmuc...@bytedance.com>
---
 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