diff options
authorNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>2014-06-06 10:00:01 -0400
committerShow Liu <show.liu@linaro.org>2014-06-18 12:05:31 +0800
commit5880749d5534dd03b5b9a0d216ae75d65c263cb7 (patch)
parent1f59aa3a698f0ce91ddc31ebd234d033f4d766a4 (diff)
mm: add !pte_present() check on existing hugetlb_entry callbacks
commit d4c54919ed86302094c0ca7d48a8cbd4ee753e92 upstream. The age 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. [ I think that reason is bogus, btw - it should just do what the regular code does, which is to call the "pte_hole()" function for such hugetlb entries - Linus] 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@oracle.com> Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> [ Backported to 3.15. Signed-off-by: Josh Boyer <jwboyer@fedoraproject.org> ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2 files changed, 6 insertions, 2 deletions
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index d54d00fb6b4..d35dbe43de5 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1412,7 +1412,7 @@ static int gather_hugetbl_stats(pte_t *pte, unsigned long hmask,
struct numa_maps *md;
struct page *page;
- if (pte_none(*pte))
+ if (!pte_present(*pte))
return 0;
page = pte_page(*pte);
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index a50d8a2dae7..15e999b5fbd 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -526,9 +526,13 @@ static void queue_pages_hugetlb_pmd_range(struct vm_area_struct *vma,
int nid;
struct page *page;
spinlock_t *ptl;
+ pte_t entry;
ptl = huge_pte_lock(hstate_vma(vma), vma->vm_mm, (pte_t *)pmd);
- page = pte_page(huge_ptep_get((pte_t *)pmd));
+ entry = huge_ptep_get((pte_t *)pmd);
+ if (!pte_present(entry))
+ goto unlock;
+ page = pte_page(entry);
nid = page_to_nid(page);
if (node_isset(nid, *nodes) == !!(flags & MPOL_MF_INVERT))
goto unlock;