The patch titled
Subject: mm/hugetlb: add migration/hwpoisoned entry check in
hugetlb_change_protection
has been added to the -mm tree. Its filename is
mm-hugetlb-add-migration-hwpoisoned-entry-check-in-hugetlb_change_protection.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-hugetlb-add-migration-hwpoisoned-entry-check-in-hugetlb_change_protection.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-hugetlb-add-migration-hwpoisoned-entry-check-in-hugetlb_change_protection.patch
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------------------------------------------------------
From: Naoya Horiguchi <[email protected]>
Subject: 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 <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: James Hogan <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Luiz Capitulino <[email protected]>
Cc: Nishanth Aravamudan <[email protected]>
Cc: Lee Schermerhorn <[email protected]>
Cc: Steve Capper <[email protected]>
Cc: <[email protected]> [2.6.36+]
Signed-off-by: Andrew Morton <[email protected]>
---
mm/hugetlb.c | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)
diff -puN
mm/hugetlb.c~mm-hugetlb-add-migration-hwpoisoned-entry-check-in-hugetlb_change_protection
mm/hugetlb.c
---
a/mm/hugetlb.c~mm-hugetlb-add-migration-hwpoisoned-entry-check-in-hugetlb_change_protection
+++ a/mm/hugetlb.c
@@ -3384,7 +3384,26 @@ unsigned long hugetlb_change_protection(
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);
_
Patches currently in -mm which might be from [email protected] are
mm-add-kpf_zero_page-flag-for-proc-kpageflags.patch
mm-hugetlb-reduce-arch-dependent-code-around-follow_huge_.patch
mm-hugetlb-pmd_huge-returns-true-for-non-present-hugepage.patch
mm-hugetlb-take-page-table-lock-in-follow_huge_pmd.patch
mm-hugetlb-fix-getting-refcount-0-page-in-hugetlb_fault.patch
mm-hugetlb-add-migration-hwpoisoned-entry-check-in-hugetlb_change_protection.patch
mm-hugetlb-add-migration-entry-check-in-__unmap_hugepage_range.patch
mm-hugetlb-fix-suboptimal-migration-hwpoisoned-entry-check.patch
mm-hugetlb-cleanup-and-rename-is_hugetlb_entry_migrationhwpoisoned.patch
do_shared_fault-check-that-mmap_sem-is-held.patch
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