linux-kernel - [PATCH v2 4/4] mm/memory-failure: me_huge

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Date:	Thu, 14 May 2015 10:39:13 +0000
From:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Andi Kleen <andi@...stfloor.org>
CC:	Dean Nelson <dnelson@...hat.com>, Tony Luck <tony.luck@...el.com>,
	"Kirill A. Shutemov" <kirill@...temov.name>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Naoya Horiguchi <nao.horiguchi@...il.com>
Subject: [PATCH v2 4/4] mm/memory-failure: me_huge_page() does nothing for
 thp

memory_failure() is supposed not to handle thp itself, but to split it. But
if something were wrong and page_action() were called on thp, me_huge_page()
(action routine for hugepages) should be better to take no action, rather
than to take wrong action prepared for hugetlb (which triggers BUG_ON().)

This change is for potential problems, but makes sense to me because thp is
an actively developing feature and this code path can be open in the future.

Signed-off-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
---
 mm/memory-failure.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git v4.1-rc3.orig/mm/memory-failure.c v4.1-rc3/mm/memory-failure.c
index 5e7795079c58..0e15fd39636a 100644
--- v4.1-rc3.orig/mm/memory-failure.c
+++ v4.1-rc3/mm/memory-failure.c
@@ -743,6 +743,10 @@ static int me_huge_page(struct page *p, unsigned long pfn)
 {
 	int res = 0;
 	struct page *hpage = compound_head(p);
+
+	if (!PageHuge(hpage))
+		return MF_DELAYED;
+
 	/*
 	 * We can safely recover from error on free or reserved (i.e.
 	 * not in-use) hugepage by dequeuing it from freelist.
-- 
2.1.0
--
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