This is a note to let you know that I've just added the patch titled
hugetlb: prevent BUG_ON in hugetlb_fault() -> hugetlb_cow()
to the 3.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
hugetlb-prevent-bug_on-in-hugetlb_fault-hugetlb_cow.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 4998a6c0edce7fae9c0a5463f6ec3fa585258ee7 Mon Sep 17 00:00:00 2001
From: Chris Metcalf <[email protected]>
Date: Thu, 10 May 2012 13:01:44 -0700
Subject: hugetlb: prevent BUG_ON in hugetlb_fault() -> hugetlb_cow()
From: Chris Metcalf <[email protected]>
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 <[email protected]>
Acked-by: Mel Gorman <[email protected]>
Acked-by: Hillf Danton <[email protected]>
Acked-by: Hugh Dickins <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: KAMEZAWA Hiroyuki <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
mm/hugetlb.c | 1 -
1 file changed, 1 deletion(-)
--- 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;
Patches currently in stable-queue which might be from [email protected] are
queue-3.0/hugetlb-prevent-bug_on-in-hugetlb_fault-hugetlb_cow.patch
queue-3.0/arch-tile-apply-commit-74fca9da0-to-the-compat-signal-handling-as-well.patch
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