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From:   Miaohe Lin <linmiaohe@huawei.com>
To:     <akpm@linux-foundation.org>, <naoya.horiguchi@nec.com>
CC:     <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
        <linmiaohe@huawei.com>
Subject: [PATCH] mm: memory-failure: fix potential page refcnt leak in memory_failure()
Date:   Sat, 1 Jul 2023 15:28:37 +0800
Message-ID: <20230701072837.1994253-1-linmiaohe@huawei.com>
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Precedence: bulk

put_ref_page() is not called to drop extra refcnt when comes from madvise
in the case pfn is valid but pgmap is NULL leading to page refcnt leak.

Fixes: 1e8aaedb182d ("mm,memory_failure: always pin the page in madvise_inject_error")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
 mm/memory-failure.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index e245191e6b04..65e2d4c5b50d 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -2080,8 +2080,6 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
 {
 	int rc = -ENXIO;
 
-	put_ref_page(pfn, flags);
-
 	/* device metadata space is not recoverable */
 	if (!pgmap_pfn_valid(pgmap, pfn))
 		goto out;
@@ -2157,6 +2155,7 @@ int memory_failure(unsigned long pfn, int flags)
 
 		if (pfn_valid(pfn)) {
 			pgmap = get_dev_pagemap(pfn, NULL);
+			put_ref_page(pfn, flags);
 			if (pgmap) {
 				res = memory_failure_dev_pagemap(pfn, flags,
 								 pgmap);
-- 
2.33.0