Re: [PATCH 1/2] mm/hwpoison: fix fail to split THP w/ refcount held

From: Wanpeng Li
Date: Mon Aug 10 2015 - 04:29:42 EST

Hi Naoya,

On 8/10/15 4:10 PM, Naoya Horiguchi wrote:
On Mon, Aug 10, 2015 at 02:32:30PM +0800, Wanpeng Li wrote:
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 <>
It seems that the same conditional put_page() would be added to
"soft offline: %#lx page already poisoned" branch too, right?

PageHWPoison() is just called before the soft_offline_page() in madvise_hwpoion(). I think the PageHWPosion()
check in soft_offline_page() makes more sense for the other soft_offline_page() callsites which don't have the
refcount held.

Wanpeng Li

mm/memory-failure.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 8077b1c..56b8a71 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1710,6 +1710,8 @@ 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",
+ if (flags & MF_COUNT_INCREASED)
+ put_page(page);
return -EBUSY;

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