From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
To: Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>
Cc: David Rientjes <rientjes@google.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Naoya Horiguchi <nao.horiguchi@gmail.com>
Subject: [PATCH v2 3/3] mm/hugetlb: add migration entry check in hugetlb_change_protection
Date: Fri, 1 Aug 2014 13:37:43 -0400 [thread overview]
Message-ID: <1406914663-8631-3-git-send-email-n-horiguchi@ah.jp.nec.com> (raw)
In-Reply-To: <1406914663-8631-1-git-send-email-n-horiguchi@ah.jp.nec.com>
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.
This patch adds is_hugetlb_entry_(migration|hwpoisoned) check in this
function and skip all such entries.
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: <stable@vger.kernel.org> # [3.12+]
---
mm/hugetlb.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git mmotm-2014-07-22-15-58.orig/mm/hugetlb.c mmotm-2014-07-22-15-58/mm/hugetlb.c
index 863f45f63cd5..1da7ca2e2a02 100644
--- mmotm-2014-07-22-15-58.orig/mm/hugetlb.c
+++ mmotm-2014-07-22-15-58/mm/hugetlb.c
@@ -3355,7 +3355,13 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
spin_unlock(ptl);
continue;
}
- if (!huge_pte_none(huge_ptep_get(ptep))) {
+ pte = huge_ptep_get(ptep);
+ if (unlikely(is_hugetlb_entry_migration(pte) ||
+ is_hugetlb_entry_hwpoisoned(pte))) {
+ spin_unlock(ptl);
+ continue;
+ }
+ if (!huge_pte_none(pte)) {
pte = huge_ptep_get_and_clear(mm, address, ptep);
pte = pte_mkhuge(huge_pte_modify(pte, newprot));
pte = arch_make_huge_pte(pte, vma, NULL, 0);
--
1.9.3
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next prev parent reply other threads:[~2014-08-01 17:40 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-01 17:37 [PATCH v2 1/3] mm/hugetlb: take refcount under page table lock in follow_huge_pmd() Naoya Horiguchi
2014-08-01 17:37 ` [PATCH v2 2/3] mm/hugetlb: use get_page_unless_zero() in hugetlb_fault() Naoya Horiguchi
2014-08-09 23:11 ` Hugh Dickins
2014-08-12 18:55 ` Naoya Horiguchi
2014-08-01 17:37 ` Naoya Horiguchi [this message]
2014-08-09 23:12 ` [PATCH v2 3/3] mm/hugetlb: add migration entry check in hugetlb_change_protection Hugh Dickins
2014-08-12 18:55 ` Naoya Horiguchi
2014-08-01 21:53 ` [PATCH v2 1/3] mm/hugetlb: take refcount under page table lock in follow_huge_pmd() Andrew Morton
2014-08-01 21:58 ` Naoya Horiguchi
2014-08-04 15:50 ` [PATCH] mm/hugetlb: remove unused argument of follow_huge_(pmd|pud) Naoya Horiguchi
2014-08-04 15:29 ` [PATCH v2 1/3] mm/hugetlb: take refcount under page table lock in follow_huge_pmd() Naoya Horiguchi
2014-08-09 23:01 ` Hugh Dickins
2014-08-12 18:55 ` Naoya Horiguchi
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