From 7d1900c744b2e4687b3e467edf58373c02bcf22d Mon Sep 17 00:00:00 2001
From: Wanpeng Li <wanpeng.li@hotmail.com>
Date: Tue, 8 Sep 2015 15:03:10 -0700
Subject: [PATCH] mm/hwpoison: fix failure to split thp w/ refcount held

THP pages will get a refcount in madvise_hwpoison() w/
MF_COUNT_INCREASED flag, however, the refcount is still held when fail
to split THP pages.

Fix it by reducing the refcount of THP pages when fail to split THP.

Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/memory-failure.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 016c814101ed..8ad923a93539 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1725,6 +1725,8 @@ int soft_offline_page(struct page *page, int flags)
 		if (PageAnon(hpage) && unlikely(split_huge_page(hpage))) {
 			pr_info("soft offline: %#lx: failed to split THP\n",
 				pfn);
+			if (flags & MF_COUNT_INCREASED)
+				put_page(page);
 			return -EBUSY;
 		}
 	}