From patchwork Thu Feb 19 00:28:36 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 441346 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 3EE001400DE; Thu, 19 Feb 2015 11:30:40 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1YOF0m-00047N-Kc; Thu, 19 Feb 2015 00:30:36 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1YOEyt-0002xE-Hq for kernel-team@lists.ubuntu.com; Thu, 19 Feb 2015 00:28:39 +0000 Received: from 1.general.kamal.us.vpn ([10.172.68.52] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1YOEyt-0004Bj-5F; Thu, 19 Feb 2015 00:28:39 +0000 Received: from kamal by fourier with local (Exim 4.82) (envelope-from ) id 1YOEyq-0003rJ-NZ; Wed, 18 Feb 2015 16:28:36 -0800 From: Kamal Mostafa To: Konstantin Khlebnikov Subject: [3.13.y-ckt stable] Patch "mm: fix corner case in anon_vma endless growing prevention" has been added to staging queue Date: Wed, 18 Feb 2015 16:28:36 -0800 Message-Id: <1424305716-14803-1-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 X-Extended-Stable: 3.13 Cc: Rik van Riel , Daniel Forrest , Kamal Mostafa , Michal Hocko , kernel-team@lists.ubuntu.com, Linus Torvalds , Vlastimil Babka X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com This is a note to let you know that I have just added a patch titled mm: fix corner case in anon_vma endless growing prevention to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue This patch is scheduled to be released in version 3.13.11-ckt16. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.13.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From bb8a46e69c5ec72cd0d1ec28ce1b35a8f4079ee6 Mon Sep 17 00:00:00 2001 From: Konstantin Khlebnikov Date: Sun, 11 Jan 2015 16:54:06 +0300 Subject: mm: fix corner case in anon_vma endless growing prevention commit b800c91a0517071156e772d4fb329ad33590da62 upstream. Fix for BUG_ON(anon_vma->degree) splashes in unlink_anon_vmas() ("kernel BUG at mm/rmap.c:399!") caused by commit 7a3ef208e662 ("mm: prevent endless growth of anon_vma hierarchy") Anon_vma_clone() is usually called for a copy of source vma in destination argument. If source vma has anon_vma it should be already in dst->anon_vma. NULL in dst->anon_vma is used as a sign that it's called from anon_vma_fork(). In this case anon_vma_clone() finds anon_vma for reusing. Vma_adjust() calls it differently and this breaks anon_vma reusing logic: anon_vma_clone() links vma to old anon_vma and updates degree counters but vma_adjust() overrides vma->anon_vma right after that. As a result final unlink_anon_vmas() decrements degree for wrong anon_vma. This patch assigns ->anon_vma before calling anon_vma_clone(). Signed-off-by: Konstantin Khlebnikov Reported-and-tested-by: Chris Clayton Reported-and-tested-by: Oded Gabbay Reported-and-tested-by: Chih-Wei Huang Acked-by: Rik van Riel Acked-by: Vlastimil Babka Cc: Daniel Forrest Cc: Michal Hocko Signed-off-by: Linus Torvalds Signed-off-by: Kamal Mostafa --- mm/mmap.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) -- 1.9.1 diff --git a/mm/mmap.c b/mm/mmap.c index de25399..d3b8887 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -744,10 +744,12 @@ again: remove_next = 1 + (end > next->vm_end); if (exporter && exporter->anon_vma && !importer->anon_vma) { int error; + importer->anon_vma = exporter->anon_vma; error = anon_vma_clone(importer, exporter); - if (error) + if (error) { + importer->anon_vma = NULL; return error; - importer->anon_vma = exporter->anon_vma; + } } }