[PATCH V2] MCE: fix an error of mce_bad_pages statistics

[Xishi Qiu <qiuxishi@huawei.com>]

On x86 platform, if we use "/sys/devices/system/memory/soft_offline_page" to offline a
free page twice, the value of mce_bad_pages will be added twice. So this is an error,
since the page was already marked HWPoison, we should skip the page and don't add the
value of mce_bad_pages.

$ cat /proc/meminfo | grep HardwareCorrupted

soft_offline_page()
	get_any_page()
		atomic_long_add(1, &mce_bad_pages)

Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
i>>?Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
---
 mm/memory-failure.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 8b20278..de760ca 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1582,8 +1582,11 @@ int soft_offline_page(struct page *page, int flags)
 		return ret;

 done:
-	atomic_long_add(1, &mce_bad_pages);
-	SetPageHWPoison(page);
 	/* keep elevated page count for bad page */
+	if (!PageHWPoison(page)) {
+		atomic_long_add(1, &mce_bad_pages);
+		SetPageHWPoison(page);
+	}
+
 	return ret;
 }
-- 
1.7.6.1


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