From patchwork Wed Aug 18 18:34:56 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Leann Ogasawara X-Patchwork-Id: 62079 X-Patchwork-Delegate: leann.ogasawara@canonical.com Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from chlorine.canonical.com (chlorine.canonical.com [91.189.94.204]) by ozlabs.org (Postfix) with ESMTP id 3B7F0B70D2 for ; Thu, 19 Aug 2010 04:35:08 +1000 (EST) Received: from localhost ([127.0.0.1] helo=chlorine.canonical.com) by chlorine.canonical.com with esmtp (Exim 4.69) (envelope-from ) id 1OlnTZ-00040u-1c; Wed, 18 Aug 2010 19:35:01 +0100 Received: from adelie.canonical.com ([91.189.90.139]) by chlorine.canonical.com with esmtp (Exim 4.69) (envelope-from ) id 1OlnTX-00040n-P5 for kernel-team@lists.ubuntu.com; Wed, 18 Aug 2010 19:34:59 +0100 Received: from hutte.canonical.com ([91.189.90.181]) by adelie.canonical.com with esmtp (Exim 4.69 #1 (Debian)) id 1OlnTX-00033e-KI for ; Wed, 18 Aug 2010 19:34:59 +0100 Received: from host-208-74-128-122.dutchbros-02.cust.visp.net ([208.74.128.122] helo=[192.168.5.201]) by hutte.canonical.com with esmtpsa (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.69) (envelope-from ) id 1OlnTX-0003QX-7R for kernel-team@lists.ubuntu.com; Wed, 18 Aug 2010 19:34:59 +0100 Subject: [Maverick] [PATCH 1/1] UBUNTU: (pre-stable) mm: fix page table unmap for stack guard page properly From: Leann Ogasawara To: kernel-team Date: Wed, 18 Aug 2010 11:34:56 -0700 Message-ID: <1282156496.2848.57.camel@emiko> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.9 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kernel-team-bounces@lists.ubuntu.com Errors-To: kernel-team-bounces@lists.ubuntu.com Hi All, On one of my test systems I was noticing a regression which produced multiple "BUG: scheduling while atomic" messages and my system would subsequently hang. This regression appears to have been introduced via the 2.6.35.2 stable patches. This has already been reported upstream [1] and a subsequent patch applied to mainline (CC'd stable). I've built and tested a Maverick kernel with the patch applied and have confirmed it resolves the regression. Even though this is likely to be included in the next 2.6.35.3 stable update, I'm proposing we pull it in as a "pre-stable" patch for Maverick as I'm already seeing bug reports in Launchpad which I believe will be resolved with this patch [2,3]. Thanks, Leann [1] https://bugzilla.kernel.org/show_bug.cgi?id=16588 [2] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/618846 [3] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/619335 >From b674cf12c3792dc8c0cbf1082d5caf945378ca97 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 14 Aug 2010 11:44:56 -0700 Subject: [PATCH] UBUNTU: (pre-stable) mm: fix page table unmap for stack guard page properly MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit We do in fact need to unmap the page table _before_ doing the whole stack guard page logic, because if it is needed (mainly 32-bit x86 with PAE and CONFIG_HIGHPTE, but other architectures may use it too) then it will do a kmap_atomic/kunmap_atomic. And those kmaps will create an atomic region that we cannot do allocations in. However, the whole stack expand code will need to do anon_vma_prepare() and vma_lock_anon_vma() and they cannot do that in an atomic region. Now, a better model might actually be to do the anon_vma_prepare() when _creating_ a VM_GROWSDOWN segment, and not have to worry about any of this at page fault time. But in the meantime, this is the straightforward fix for the issue. See https://bugzilla.kernel.org/show_bug.cgi?id=16588 for details. Reported-by: Wylda Reported-by: Sedat Dilek Reported-by: Mike Pagano Reported-by: François Valenduc Tested-by: Ed Tomlinson Cc: Pekka Enberg Cc: Greg KH Cc: stable@kernel.org Signed-off-by: Linus Torvalds (cherry picked from commit 11ac552477e32835cb6970bf0a70c210807f5673) Signed-off-by: Leann Ogasawara Acked-by: Tim Gardner --- mm/memory.c | 13 ++++++------- 1 files changed, 6 insertions(+), 7 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index 4e23287..4122947 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2792,24 +2792,23 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, spinlock_t *ptl; pte_t entry; - if (check_stack_guard_page(vma, address) < 0) { - pte_unmap(page_table); + pte_unmap(page_table); + + /* Check if we need to add a guard page to the stack */ + if (check_stack_guard_page(vma, address) < 0) return VM_FAULT_SIGBUS; - } + /* Use the zero-page for reads */ if (!(flags & FAULT_FLAG_WRITE)) { entry = pte_mkspecial(pfn_pte(my_zero_pfn(address), vma->vm_page_prot)); - ptl = pte_lockptr(mm, pmd); - spin_lock(ptl); + page_table = pte_offset_map_lock(mm, pmd, address, &ptl); if (!pte_none(*page_table)) goto unlock; goto setpte; } /* Allocate our own private page. */ - pte_unmap(page_table); - if (unlikely(anon_vma_prepare(vma))) goto oom; page = alloc_zeroed_user_highpage_movable(vma, address);