[PATCH v5 5/8] mm/hugetlb: add migration/hwpoisoned entry check in hugetlb_change_protection
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 Cc: # [2.6.36+] --- ChangeLog v4: - s/set_pte_at/set_huge_pte_at/ ChangeLog v3: - handle migration entry correctly (instead of just skipping) --- mm/hugetlb.c | 21 - 1 file changed, 20 insertions(+), 1 deletion(-) diff --git mmotm-2014-11-26-15-45.orig/mm/hugetlb.c mmotm-2014-11-26-15-45/mm/hugetlb.c index dfc1527e8f4e..2807be3f260d 100644 --- mmotm-2014-11-26-15-45.orig/mm/hugetlb.c +++ mmotm-2014-11-26-15-45/mm/hugetlb.c @@ -3384,7 +3384,26 @@ 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_hwpoisoned(pte))) { + spin_unlock(ptl); + 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(); + newpte = swp_entry_to_pte(entry); + set_huge_pte_at(mm, address, ptep, newpte); + pages++; + } + 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); -- 2.2.0.rc0.2.gf745acb -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH v5 5/8] mm/hugetlb: add migration/hwpoisoned entry check in hugetlb_change_protection
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-horigu...@ah.jp.nec.com Cc: sta...@vger.kernel.org # [2.6.36+] --- ChangeLog v4: - s/set_pte_at/set_huge_pte_at/ ChangeLog v3: - handle migration entry correctly (instead of just skipping) --- mm/hugetlb.c | 21 - 1 file changed, 20 insertions(+), 1 deletion(-) diff --git mmotm-2014-11-26-15-45.orig/mm/hugetlb.c mmotm-2014-11-26-15-45/mm/hugetlb.c index dfc1527e8f4e..2807be3f260d 100644 --- mmotm-2014-11-26-15-45.orig/mm/hugetlb.c +++ mmotm-2014-11-26-15-45/mm/hugetlb.c @@ -3384,7 +3384,26 @@ 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_hwpoisoned(pte))) { + spin_unlock(ptl); + 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); + pages++; + } + 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); -- 2.2.0.rc0.2.gf745acb -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/