[PATCH] mm, hwpoison, hugetlb: Check hugetlb head page hwpoison flag when unpoison page

[luofei <luofei@unicloud.com>]

When software-poison a huge page, if dissolve_free_huge_page() failed,
the huge page will be added to hugepage_freelists. In this case, the
head page will hold the hwpoison flag, but the real poisoned tail page
hwpoison flag is not set, this will cause unpoison_memory() fail to
unpoison the previously poisoned page.

So add a check on hugetlb head page, and also need to ensure the
previously poisoned tail page in huge page raw_hwp_list.

Signed-off-by: luofei <luofei@unicloud.com>
---
 mm/memory-failure.c | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 14439806b5ef..fc571b0ceb9d 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -2293,6 +2293,28 @@ core_initcall(memory_failure_init);
 		pr_info(fmt, pfn);			\
 })
 
+static bool hugetlb_page_head_poison(struct page *hpage, struct page *page)
+{
+	struct llist_head *head;
+	struct llist_node *t, *tnode;
+	struct raw_hwp_page *p;
+
+	if (PageHuge(page) && PageHWPoison(hpage) && HPageFreed(hpage))
+		return false;
+
+	if (HPageRawHwpUnreliable(hpage))
+		return false;
+
+	head = raw_hwp_list_head(hpage);
+	llist_for_each_safe(tnode, t, head->first) {
+		p = container_of(tnode, struct raw_hwp_page, node);
+		if (p->page == page)
+			return true;
+	}
+
+	return false;
+}
+
 /**
  * unpoison_memory - Unpoison a previously poisoned page
  * @pfn: Page number of the to be unpoisoned page
@@ -2330,7 +2352,7 @@ int unpoison_memory(unsigned long pfn)
 		goto unlock_mutex;
 	}
 
-	if (!PageHWPoison(p)) {
+	if (!PageHWPoison(p) && !hugetlb_page_head_poison(page, p)) {
 		unpoison_pr_info("Unpoison: Page was already unpoisoned %#lx\n",
 				 pfn, &unpoison_rs);
 		goto unlock_mutex;
-- 
2.27.0