From afe85051b486d5d558d93ab2e509dc3bfdffc2c5 Mon Sep 17 00:00:00 2001 From: Chris Metcalf <cmetcalf@tilera.com> Date: Thu, 10 May 2012 13:01:44 -0700 Subject: 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- mm/hugetlb.c | 1 - 1 file changed, 1 deletion(-) (limited to 'mm') diff --git a/mm/hugetlb.c b/mm/hugetlb.c index f7001ac..00b0abb 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2398,7 +2398,6 @@ 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; -- cgit v1.1