linux-kernel - [PATCH v5 3/4] mm,hwpoison: take free pages off the buddy freelists for hugetlb

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Date:   Tue, 13 Oct 2020 16:44:46 +0200
From:   Oscar Salvador <osalvador@...e.de>
To:     n-horiguchi@...jp.nec.com
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Oscar Salvador <osalvador@...e.de>
Subject: [PATCH v5 3/4] mm,hwpoison: take free pages off the buddy freelists for hugetlb

Currently, free hugetlb get dissolved, but we also need to make sure
to take the poisoned subpage off the buddy frelists, so no one stumbles
upon it (see previous patch for more information).

Signed-off-by: Oscar Salvador <osalvador@...e.de>
---
 mm/memory-failure.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 181bed890c16..30aadeca97d2 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -809,7 +809,7 @@ static int me_swapcache_clean(struct page *p, unsigned long pfn)
  */
 static int me_huge_page(struct page *p, unsigned long pfn)
 {
-	int res = 0;
+	int res;
 	struct page *hpage = compound_head(p);
 	struct address_space *mapping;
 
@@ -820,6 +820,7 @@ static int me_huge_page(struct page *p, unsigned long pfn)
 	if (mapping) {
 		res = truncate_error_page(hpage, pfn, mapping);
 	} else {
+		res = MF_FAILED;
 		unlock_page(hpage);
 		/*
 		 * migration entry prevents later access on error anonymous
@@ -828,8 +829,10 @@ static int me_huge_page(struct page *p, unsigned long pfn)
 		 */
 		if (PageAnon(hpage))
 			put_page(hpage);
-		dissolve_free_huge_page(p);
-		res = MF_RECOVERED;
+		if (!dissolve_free_huge_page(p) && take_page_off_buddy(p)) {
+			page_ref_inc(p);
+			res = MF_RECOVERED;
+		}
 		lock_page(hpage);
 	}
 
@@ -1198,9 +1201,13 @@ static int memory_failure_hugetlb(unsigned long pfn, int flags)
 			}
 		}
 		unlock_page(head);
-		dissolve_free_huge_page(p);
-		action_result(pfn, MF_MSG_FREE_HUGE, MF_DELAYED);
-		return 0;
+		res = MF_FAILED;
+		if (!dissolve_free_huge_page(p) && take_page_off_buddy(p)) {
+			page_ref_inc(p);
+			res = MF_RECOVERED;
+		}
+		action_result(pfn, MF_MSG_FREE_HUGE, res);
+		return res == MF_RECOVERED ? 0 : -EBUSY;
 	}
 
 	lock_page(head);
-- 
2.26.2