HWPOISON, hugetlb: add free check to dequeue_hwpoison_huge_page()

This check is necessary to avoid race between dequeue and allocation,
which can cause a free hugepage to be dequeued twice and get kernel unstable.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 757f6b0accfe..5c7158a11592 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -698,6 +698,7 @@ static int me_swapcache_clean(struct page *p, unsigned long pfn)
  */
 static int me_huge_page(struct page *p, unsigned long pfn)
 {
+        int res = 0;
         struct page *hpage = compound_head(p);
         /*
          * We can safely recover from error on free or reserved (i.e.
@@ -710,8 +711,9 @@ static int me_huge_page(struct page *p, unsigned long pfn)
          * so there is no race between isolation and mapping/unmapping.
          */
         if (!(page_mapping(hpage) || PageAnon(hpage))) {
-                __isolate_hwpoisoned_huge_page(hpage);
-                return RECOVERED;
+                res = dequeue_hwpoisoned_huge_page(hpage);
+                if (!res)
+                        return RECOVERED;
         }
         return DELAYED;
 }