hugetlb: prevent BUG_ON in hugetlb_fault() -> hugetlb_cow()
authorChris Metcalf <cmetcalf@tilera.com>
Thu, 10 May 2012 20:01:44 +0000 (13:01 -0700)
committerVarun Wadekar <vwadekar@nvidia.com>
Fri, 18 May 2012 10:36:51 +0000 (15:36 +0530)
commited002a1c3dc0a44aca18ca3453ad56cee982fbc6
tree40aabde52ae59d93f560af070e5fe1fcefb4ca37
parent056de96d166e6bc352d67134f40d5af4e78b263c
hugetlb: prevent BUG_ON in hugetlb_fault() -> hugetlb_cow()

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>
Cc: <stable@vger.kernel.org> [3.0.29+, 3.2.16+, 3.3.3+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/hugetlb.c