From: Chris Metcalf <cmetcalf@tilera.com>
To: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mel@csn.ul.ie>,
Andrew Morton <akpm@linux-foundation.org>,
Hillf Danton <dhillf@gmail.com>, Michal Hocko <mhocko@suse.cz>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
<linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] hugetlb: avoid gratuitous BUG_ON in hugetlb_fault() -> hugetlb_cow()
Date: Sun, 29 Apr 2012 15:04:51 -0400 [thread overview]
Message-ID: <201205011333.q41DXsK7026759@farm-0013.internal.tilera.com> (raw)
In-Reply-To: <20120501131413.GA11435@suse.de>
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@tilera.com>
---
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
next prev parent reply other threads:[~2012-05-01 13:33 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-29 19:04 [PATCH] hugetlb: avoid gratuitous BUG_ON in hugetlb_fault() -> hugetlb_cow() Chris Metcalf
2012-04-30 20:19 ` Hugh Dickins
2012-05-01 13:14 ` Mel Gorman
2012-04-29 19:04 ` Chris Metcalf [this message]
2012-05-01 13:47 ` Mel Gorman
2012-05-01 13:53 ` Hillf Danton
2012-05-01 15:43 ` Hugh Dickins
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