| From | Jiri Slaby <> | Subject | [PATCH 3.12 050/181] mm: add !pte_present() check on existing hugetlb_entry callbacks | Date | Mon, 30 Jun 2014 13:51:11 +0200 |
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From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
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> Cc: <stable@vger.kernel.org> [3.12+] 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: Jiri Slaby <jslaby@suse.cz> --- fs/proc/task_mmu.c | 2 +- mm/mempolicy.c | 6 +++++- 2 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 390bdab01c3c..ad4df869c907 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1353,7 +1353,7 @@ 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 927a69cf354a..a005cc9f6f18 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -525,9 +525,13 @@ static void queue_pages_hugetlb_pmd_range(struct vm_area_struct *vma, #ifdef CONFIG_HUGETLB_PAGE int nid; struct page *page; + pte_t entry; spin_lock(&vma->vm_mm->page_table_lock); - 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; -- 2.0.0
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