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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 6/6] mm, hwpoison: avoid trying to unpoison reserved page
Date:   Thu, 18 Aug 2022 21:00:16 +0800
Message-ID: <20220818130016.45313-7-linmiaohe@huawei.com>
In-Reply-To: <20220818130016.45313-1-linmiaohe@huawei.com>
References: <20220818130016.45313-1-linmiaohe@huawei.com>
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For reserved pages, HWPoison flag will be set without increasing the page
refcnt. So we shouldn't even try to unpoison these pages and thus decrease
the page refcnt unexpectly. Add a PageReserved() check to filter this case
out and remove the below unneeded zero page (zero page is reserved) check.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
 mm/memory-failure.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 5f9615a86296..c831c41bb092 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -2355,7 +2355,7 @@ int unpoison_memory(unsigned long pfn)
 		goto unlock_mutex;
 	}
 
-	if (PageSlab(page) || PageTable(page))
+	if (PageSlab(page) || PageTable(page) || PageReserved(page))
 		goto unlock_mutex;
 
 	ret = get_hwpoison_page(p, MF_UNPOISON);
@@ -2386,7 +2386,7 @@ int unpoison_memory(unsigned long pfn)
 		freeit = !!TestClearPageHWPoison(p);
 
 		put_page(page);
-		if (freeit && !(pfn == my_zero_pfn(0) && page_count(p) == 1)) {
+		if (freeit) {
 			put_page(page);
 			ret = 0;
 		}
-- 
2.23.0