linux-kernel - [PATCH v2 2/2] mm/memory-failure.c: dissolve truncated hugetlb page

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Message-ID: <20220414114941.11223-3-linmiaohe@huawei.com>
Date:   Thu, 14 Apr 2022 19:49:41 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <akpm@...ux-foundation.org>, <naoya.horiguchi@....com>
CC:     <shy828301@...il.com>, <david@...hat.com>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, <linmiaohe@...wei.com>
Subject: [PATCH v2 2/2] mm/memory-failure.c: dissolve truncated hugetlb page

If me_huge_page meets a truncated but not yet freed hugepage, it won't be
dissolved even if we hold the last refcnt. It's because the hugepage has
NULL page_mapping while it's not anonymous hugepage too. Thus we lose the
last chance to dissolve it into buddy to save healthy subpages. Remove
PageAnon check to handle these hugepages too.

Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
---
 mm/memory-failure.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 488aaca72340..1d64bfff339d 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1041,12 +1041,11 @@ static int me_huge_page(struct page_state *ps, struct page *p)
 		res = MF_FAILED;
 		unlock_page(hpage);
 		/*
-		 * migration entry prevents later access on error anonymous
-		 * hugepage, so we can free and dissolve it into buddy to
-		 * save healthy subpages.
+		 * migration entry prevents later access on error hugepage,
+		 * so we can free and dissolve it into buddy to save healthy
+		 * subpages.
 		 */
-		if (PageAnon(hpage))
-			put_page(hpage);
+		put_page(hpage);
 		if (__page_handle_poison(p)) {
 			page_ref_inc(p);
 			res = MF_RECOVERED;
-- 
2.23.0