Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753443AbaLOOe3 (ORCPT ); Mon, 15 Dec 2014 09:34:29 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:38993 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753063AbaLOO3O (ORCPT ); Mon, 15 Dec 2014 09:29:14 -0500 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Daniel Forrest , Konstantin Khlebnikov , Andrea Arcangeli , Rik van Riel , Tim Hartrick , Hugh Dickins , Michel Lespinasse , Vlastimil Babka , Andrew Morton , Linus Torvalds , Luis Henriques Subject: [PATCH 3.16.y-ckt 146/168] mm: fix anon_vma_clone() error treatment Date: Mon, 15 Dec 2014 14:26:40 +0000 Message-Id: <1418653622-21105-147-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 2.1.3 In-Reply-To: <1418653622-21105-1-git-send-email-luis.henriques@canonical.com> References: <1418653622-21105-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.7-ckt3 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Daniel Forrest commit c4ea95d7cd08d9ffd7fa75e6c5e0332d596dd11e upstream. Andrew Morton noticed that the error return from anon_vma_clone() was being dropped and replaced with -ENOMEM (which is not itself a bug because the only error return value from anon_vma_clone() is -ENOMEM). I did an audit of callers of anon_vma_clone() and discovered an actual bug where the error return was being lost. In __split_vma(), between Linux 3.11 and 3.12 the code was changed so the err variable is used before the call to anon_vma_clone() and the default initial value of -ENOMEM is overwritten. So a failure of anon_vma_clone() will return success since err at this point is now zero. Below is a patch which fixes this bug and also propagates the error return value from anon_vma_clone() in all cases. Fixes: ef0855d334e1 ("mm: mempolicy: turn vma_set_policy() into vma_dup_policy()") Signed-off-by: Daniel Forrest Reviewed-by: Michal Hocko Cc: Konstantin Khlebnikov Cc: Andrea Arcangeli Cc: Rik van Riel Cc: Tim Hartrick Cc: Hugh Dickins Cc: Michel Lespinasse Cc: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Luis Henriques --- mm/mmap.c | 10 +++++++--- mm/rmap.c | 6 ++++-- 2 files changed, 11 insertions(+), 5 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 874e0e5ea193..4813ecec5a94 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -747,8 +747,11 @@ again: remove_next = 1 + (end > next->vm_end); * shrinking vma had, to cover any anon pages imported. */ if (exporter && exporter->anon_vma && !importer->anon_vma) { - if (anon_vma_clone(importer, exporter)) - return -ENOMEM; + int error; + + error = anon_vma_clone(importer, exporter); + if (error) + return error; importer->anon_vma = exporter->anon_vma; } } @@ -2430,7 +2433,8 @@ static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma, if (err) goto out_free_vma; - if (anon_vma_clone(new, vma)) + err = anon_vma_clone(new, vma); + if (err) goto out_free_mpol; if (new->vm_file) diff --git a/mm/rmap.c b/mm/rmap.c index 22a4a7699cdb..78274432b48f 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -274,6 +274,7 @@ int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma) { struct anon_vma_chain *avc; struct anon_vma *anon_vma; + int error; /* Don't bother if the parent process has no anon_vma here. */ if (!pvma->anon_vma) @@ -283,8 +284,9 @@ int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma) * First, attach the new VMA to the parent VMA's anon_vmas, * so rmap can find non-COWed pages in child processes. */ - if (anon_vma_clone(vma, pvma)) - return -ENOMEM; + error = anon_vma_clone(vma, pvma); + if (error) + return error; /* Then add our own anon_vma. */ anon_vma = anon_vma_alloc(); -- 2.1.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/