From: Chris Metcalf <cmetcalf@tilera.com>
Date: Thu, 10 May 2012 20:01:44 +0000 (-0700)
Subject: hugetlb: prevent BUG_ON in hugetlb_fault() -> hugetlb_cow()
X-Git-Tag: v3.4-rc7~13^2~5
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4998a6c0edce7fae9c0a5463f6ec3fa585258ee7;p=pandora-kernel.git

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>
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