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authorChris Metcalf <cmetcalf@tilera.com>2012-05-10 13:01:44 -0700
committerBen Hutchings <ben@decadent.org.uk>2012-05-20 22:56:32 +0100
commita9760061391e46f56fb6a8636142dab39f345e9b (patch)
tree71b4e5f8737c1ca458d92f86d4ab7996d6f5ef48 /mm
parent8a2f7257ae6a7d1e1c87dd1ef146bd3e9c04e903 (diff)
hugetlb: prevent BUG_ON in hugetlb_fault() -> hugetlb_cow()
commit 4998a6c0edce7fae9c0a5463f6ec3fa585258ee7 upstream. Commit 66aebce747eaf ("hugetlb: fix race condition in hugetlb_fault()") 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. The 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@tilera.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Acked-by: Hillf Danton <dhillf@gmail.com> Acked-by: Hugh Dickins <hughd@google.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'mm')
-rw-r--r--mm/hugetlb.c1
1 files changed, 0 insertions, 1 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index bd936ede7329..7120c2e2cf82 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2405,7 +2405,6 @@ 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);
goto retry_avoidcopy;