Re: [PATCH] hugetlb: avoid gratuitous BUG_ON in hugetlb_fault() ->hugetlb_cow()

[Chris Metcalf]

Commit 66aebce747eaf added code to avoid a race condition by
elevating the page refcount in hugetlb_fault() while calling
hugetlb_cow().  However, one code path in hugetlb_cow() includes
an assertion that the page count is 1, whereas it may now also
have the value 2 in this path.  Consensus is that this BUG_ON
has served its purpose, so rather than extending it to cover both
cases, we just remove it.

Signed-off-by: Chris Metcalf <cmetcalf@xxxxxxxxxx>
---
 mm/hugetlb.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index cd65cb1..baaad5d 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2498,7 +2498,6 @@ retry_avoidcopy:
 		if (outside_reserve) {
 			BUG_ON(huge_pte_none(pte));
 			if (unmap_ref_private(mm, vma, old_page, address)) {
-				BUG_ON(page_count(old_page) != 1);
 				BUG_ON(huge_pte_none(pte));
 				spin_lock(&mm->page_table_lock);
 				ptep = huge_pte_offset(mm, address & huge_page_mask(h));
-- 
1.6.5.2

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/