[PATCH 2/3] HWPOISON, hugetlbfs: fix "bad pmd" warning in unmapping hwpoisoned hugepage

[Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>]

When a process which used a hwpoisoned hugepage tries to exit() or
munmap(), the kernel can print out "bad pmd" message because page
table walker in free_pgtables() encounters 'hwpoisoned entry' on pmd.

This is because currently we fail to clear the hwpoisoned entry in
__unmap_hugepage_range(), so this patch simply does it.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
 mm/hugetlb.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git v3.7-rc8.orig/mm/hugetlb.c v3.7-rc8/mm/hugetlb.c
index e61a749..fe7c2a7 100644
--- v3.7-rc8.orig/mm/hugetlb.c
+++ v3.7-rc8/mm/hugetlb.c
@@ -2387,8 +2387,10 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
 		/*
 		 * HWPoisoned hugepage is already unmapped and dropped reference
 		 */
-		if (unlikely(is_hugetlb_entry_hwpoisoned(pte)))
+		if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) {
+			pte_clear(mm, address, ptep);
 			continue;
+		}
 
 		page = pte_page(pte);
 		/*
-- 
1.7.11.7

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