Messages in this thread Patch in this message | | | From | Naoya Horiguchi <> | Subject | [PATCH v2 3/3] mm/hugetlb: add migration entry check in hugetlb_change_protection | Date | Fri, 1 Aug 2014 13:37:43 -0400 |
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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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