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Date: Tue, 05 May 2015 02:16:39 +0100
From: Ben Hutchings <ben@...adent.org.uk>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC: akpm@...ux-foundation.org,
"Lee Schermerhorn" <lee.schermerhorn@...com>,
"David Rientjes" <rientjes@...gle.com>,
"James Hogan" <james.hogan@...tec.com>,
"Rik van Riel" <riel@...hat.com>, "Mel Gorman" <mel@....ul.ie>,
"Naoya Horiguchi" <n-horiguchi@...jp.nec.com>,
"Steve Capper" <steve.capper@...aro.org>,
"Andrea Arcangeli" <aarcange@...hat.com>,
"Hugh Dickins" <hughd@...gle.com>,
"Nishanth Aravamudan" <nacc@...ux.vnet.ibm.com>,
"Johannes Weiner" <hannes@...xchg.org>,
"Michal Hocko" <mhocko@...e.cz>,
"Luiz Capitulino" <lcapitulino@...hat.com>,
"Linus Torvalds" <torvalds@...ux-foundation.org>
Subject: [PATCH 3.2 035/221] mm/hugetlb: add migration/hwpoisoned entry
check in hugetlb_change_protection
3.2.69-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
commit a8bda28d87c38c6aa93de28ba5d30cc18e865a11 upstream.
There is a race condition between hugepage migration and
change_protection(), where hugetlb_change_protection() doesn't care about
migration entries and wrongly overwrites them. That causes unexpected
results like kernel crash. HWPoison entries also can cause the same
problem.
This patch adds is_hugetlb_entry_(migration|hwpoisoned) check in this
function to do proper actions.
Fixes: 290408d4a2 ("hugetlb: hugepage migration core")
Signed-off-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Cc: Hugh Dickins <hughd@...gle.com>
Cc: James Hogan <james.hogan@...tec.com>
Cc: David Rientjes <rientjes@...gle.com>
Cc: Mel Gorman <mel@....ul.ie>
Cc: Johannes Weiner <hannes@...xchg.org>
Cc: Michal Hocko <mhocko@...e.cz>
Cc: Rik van Riel <riel@...hat.com>
Cc: Andrea Arcangeli <aarcange@...hat.com>
Cc: Luiz Capitulino <lcapitulino@...hat.com>
Cc: Nishanth Aravamudan <nacc@...ux.vnet.ibm.com>
Cc: Lee Schermerhorn <lee.schermerhorn@...com>
Cc: Steve Capper <steve.capper@...aro.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
[bwh: Backported to 3.2:
- Adjust context
- We don't have split page table locks, so don't unlock inside the loop
- We don't count pages here]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
mm/hugetlb.c | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3037,7 +3037,22 @@ void hugetlb_change_protection(struct vm
continue;
if (huge_pmd_unshare(mm, &address, ptep))
continue;
- if (!huge_pte_none(huge_ptep_get(ptep))) {
+ pte = huge_ptep_get(ptep);
+ if (unlikely(is_hugetlb_entry_hwpoisoned(pte)))
+ continue;
+ if (unlikely(is_hugetlb_entry_migration(pte))) {
+ swp_entry_t entry = pte_to_swp_entry(pte);
+
+ if (is_write_migration_entry(entry)) {
+ pte_t newpte;
+
+ make_migration_entry_read(&entry);
+ newpte = swp_entry_to_pte(entry);
+ set_huge_pte_at(mm, address, ptep, newpte);
+ }
+ continue;
+ }
+ if (!huge_pte_none(pte)) {
pte = huge_ptep_get_and_clear(mm, address, ptep);
pte = pte_mkhuge(pte_modify(pte, newprot));
set_huge_pte_at(mm, address, ptep, pte);
--
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