linux-kernel - [PATCH v8 2/3] mm/hwpoison: put page in already hwpoisoned case with MF_COUNT

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Date:   Fri,  8 Apr 2022 22:53:22 +0900
From:   Naoya Horiguchi <naoya.horiguchi@...ux.dev>
To:     linux-mm@...ck.org
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Yang Shi <shy828301@...il.com>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Naoya Horiguchi <naoya.horiguchi@....com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v8 2/3] mm/hwpoison: put page in already hwpoisoned case with MF_COUNT_INCREASED

From: Naoya Horiguchi <naoya.horiguchi@....com>

In already hwpoisoned case, memory_failure() is supposed to return with
releasing the page refcount taken for error handling. But currently the
refcount is not released when called with MF_COUNT_INCREASED, which
makes page refcount inconsistent.  This should be rare and non-critical,
but it might be inconvenient in testing (unpoison doesn't work).

Suggested-by: Miaohe Lin <linmiaohe@...wei.com>
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@....com>
---
 mm/memory-failure.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 2020944398c9..b2e32cdc3823 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1811,6 +1811,8 @@ int memory_failure(unsigned long pfn, int flags)
 		res = -EHWPOISON;
 		if (flags & MF_ACTION_REQUIRED)
 			res = kill_accessing_process(current, pfn, flags);
+		if (flags & MF_COUNT_INCREASED)
+			put_page(p);
 		goto unlock_mutex;
 	}
 
-- 
2.25.1