linux-kernel - [PATCH 4.1 04/78] mm/hwpoison: fix fail isolate hugetlbfs page w/ refcount held

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Date:	Fri, 11 Sep 2015 15:49:05 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Wanpeng Li <wanpeng.li@...mail.com>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.1 04/78] mm/hwpoison: fix fail isolate hugetlbfs page w/ refcount held

4.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Wanpeng Li <wanpeng.li@...mail.com>

commit 036138080a4376e5f3e5d0cca8ac99084c5cf06e upstream.

Hugetlbfs pages will get a refcount in get_any_page() or
madvise_hwpoison() if soft offlining through madvise.  The refcount which
is held by the soft offline path should be released if we fail to isolate
hugetlbfs pages.

Fix it by reducing the refcount for both isolation success and failure.

Signed-off-by: Wanpeng Li <wanpeng.li@...mail.com>
Acked-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 mm/memory-failure.c |   13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1589,13 +1589,12 @@ static int soft_offline_huge_page(struct
 	unlock_page(hpage);
 
 	ret = isolate_huge_page(hpage, &pagelist);
-	if (ret) {
-		/*
-		 * get_any_page() and isolate_huge_page() takes a refcount each,
-		 * so need to drop one here.
-		 */
-		put_page(hpage);
-	} else {
+	/*
+	 * get_any_page() and isolate_huge_page() takes a refcount each,
+	 * so need to drop one here.
+	 */
+	put_page(hpage);
+	if (!ret) {
 		pr_info("soft offline: %#lx hugepage failed to isolate\n", pfn);
 		return -EBUSY;
 	}


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