Subject: + mm-add-pte_present-check-on-existing-hugetlb_entry-callbacks.patch added to -mm tree
To: n-horiguchi@xxxxxxxxxxxxx,riel@xxxxxxxxxx,sasha.levin@xxxxxxxxxx,stable@xxxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Wed, 19 Mar 2014 13:25:22 -0700
The patch titled
Subject: mm: add !pte_present() check on existing hugetlb_entry callbacks
has been added to the -mm tree. Its filename is
mm-add-pte_present-check-on-existing-hugetlb_entry-callbacks.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-add-pte_present-check-on-existing-hugetlb_entry-callbacks.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-add-pte_present-check-on-existing-hugetlb_entry-callbacks.patch
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------------------------------------------------------
From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Subject: mm: add !pte_present() check on existing hugetlb_entry callbacks
Page table walker doesn't check non-present hugetlb entry in common path,
so hugetlb_entry() callbacks must check it. The reason for this behavior
is that some callers want to handle it in its own way.
However, some callers don't check it now, which causes unpredictable
result, for example when we have a race between migrating hugepage and
reading /proc/pid/numa_maps. This patch fixes it by adding !pte_present
checks on buggy callbacks.
This bug exists for years and got visible by introducing hugepage migration.
ChangeLog v2:
- fix if condition (check !pte_present() instead of pte_present())
Reported-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [3.12+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/task_mmu.c | 3 +++
mm/mempolicy.c | 6 +++++-
2 files changed, 8 insertions(+), 1 deletion(-)
diff -puN fs/proc/task_mmu.c~mm-add-pte_present-check-on-existing-hugetlb_entry-callbacks fs/proc/task_mmu.c
--- a/fs/proc/task_mmu.c~mm-add-pte_present-check-on-existing-hugetlb_entry-callbacks
+++ a/fs/proc/task_mmu.c
@@ -1299,6 +1299,9 @@ static int gather_hugetlb_stats(pte_t *p
if (pte_none(*pte))
return 0;
+ if (!pte_present(*pte))
+ return 0;
+
page = pte_page(*pte);
if (!page)
return 0;
diff -puN mm/mempolicy.c~mm-add-pte_present-check-on-existing-hugetlb_entry-callbacks mm/mempolicy.c
--- a/mm/mempolicy.c~mm-add-pte_present-check-on-existing-hugetlb_entry-callbacks
+++ a/mm/mempolicy.c
@@ -524,8 +524,12 @@ static int queue_pages_hugetlb(pte_t *pt
unsigned long flags = qp->flags;
int nid;
struct page *page;
+ pte_t entry;
- page = pte_page(huge_ptep_get(pte));
+ entry = huge_ptep_get(pte);
+ if (!pte_present(entry))
+ return 0;
+ page = pte_page(entry);
nid = page_to_nid(page);
if (node_isset(nid, *qp->nmask) == !!(flags & MPOL_MF_INVERT))
return 0;
_
Patches currently in -mm which might be from n-horiguchi@xxxxxxxxxxxxx are
mm-hugetlb-unify-region-structure-handling.patch
mm-hugetlb-improve-cleanup-resv_map-parameters.patch
mm-hugetlb-fix-race-in-region-tracking.patch
mm-hugetlb-remove-resv_map_put.patch
mm-hugetlb-use-vma_resv_map-map-types.patch
mm-hugetlb-improve-page-fault-scalability.patch
mm-hugetlb-improve-page-fault-scalability-fix.patch
mm-hugetlbfs-fix-rmapping-for-anonymous-hugepages-with-page_pgoff.patch
mm-hugetlbfs-fix-rmapping-for-anonymous-hugepages-with-page_pgoff-v2.patch
mm-hugetlbfs-fix-rmapping-for-anonymous-hugepages-with-page_pgoff-v3.patch
mm-hugetlbfs-fix-rmapping-for-anonymous-hugepages-with-page_pgoff-v3-fix.patch
pagewalk-update-page-table-walker-core.patch
pagewalk-update-page-table-walker-core-fix-end-address-calculation-in-walk_page_range.patch
pagewalk-update-page-table-walker-core-fix-end-address-calculation-in-walk_page_range-fix.patch
pagewalk-add-walk_page_vma.patch
smaps-redefine-callback-functions-for-page-table-walker.patch
clear_refs-redefine-callback-functions-for-page-table-walker.patch
pagemap-redefine-callback-functions-for-page-table-walker.patch
numa_maps-redefine-callback-functions-for-page-table-walker.patch
memcg-redefine-callback-functions-for-page-table-walker.patch
madvise-redefine-callback-functions-for-page-table-walker.patch
arch-powerpc-mm-subpage-protc-use-walk_page_vma-instead-of-walk_page_range.patch
pagewalk-remove-argument-hmask-from-hugetlb_entry.patch
pagewalk-remove-argument-hmask-from-hugetlb_entry-fix.patch
pagewalk-remove-argument-hmask-from-hugetlb_entry-fix-fix.patch
mempolicy-apply-page-table-walker-on-queue_pages_range.patch
mm-add-pte_present-check-on-existing-hugetlb_entry-callbacks.patch
mm-call-vma_adjust_trans_huge-only-for-thp-enabled-vma.patch
mm-rename-__do_fault-do_fault.patch
mm-do_fault-extract-to-call-vm_ops-do_fault-to-separate-function.patch
mm-introduce-do_read_fault.patch
mm-introduce-do_cow_fault.patch
mm-introduce-do_shared_fault-and-drop-do_fault.patch
mm-introduce-do_shared_fault-and-drop-do_fault-fix.patch
mm-introduce-do_shared_fault-and-drop-do_fault-fix-fix.patch
mm-consolidate-code-to-call-vm_ops-page_mkwrite.patch
mm-consolidate-code-to-call-vm_ops-page_mkwrite-fix.patch
mm-consolidate-code-to-setup-pte.patch
do_shared_fault-check-that-mmap_sem-is-held.patch
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