From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967348AbaFQWeV (ORCPT ); Tue, 17 Jun 2014 18:34:21 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:54091 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966286AbaFQVs5 (ORCPT ); Tue, 17 Jun 2014 17:48:57 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Naoya Horiguchi , Rik van Riel , Andrew Morton , Linus Torvalds , Kamal Mostafa Subject: [PATCH 3.13 212/212] mm: add !pte_present() check on existing hugetlb_entry callbacks Date: Tue, 17 Jun 2014 14:45:06 -0700 Message-Id: <1403041506-13646-213-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1403041506-13646-1-git-send-email-kamal@canonical.com> References: <1403041506-13646-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13.11.4 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Naoya Horiguchi 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 Signed-off-by: Naoya Horiguchi Cc: Rik van Riel Signed-off-by: Andrew Morton [ Backported to 3.15. Signed-off-by: Josh Boyer ] Signed-off-by: Linus Torvalds Signed-off-by: Kamal Mostafa --- 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 fb52b54..8f78819 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1350,7 +1350,7 @@ 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 cb2f3dd..e980746 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; -- 1.9.1